1
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Liu Z, Li X, Reisz RR. The age and growth information of a ctenoid scale fossil from the Upper Cretaceous Nenjiang Formation in Songliao Basin, China. PLoS One 2024; 19:e0303198. [PMID: 38701057 PMCID: PMC11068172 DOI: 10.1371/journal.pone.0303198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/20/2024] [Indexed: 05/05/2024] Open
Abstract
The study of morphological characteristics and growth information in fish scales is a crucial component of modern fishery biological research, while it has been less studied in fossil materials. This paper presents a detailed morphological description and growth analysis of a fossil ctenoid scale obtained from the Upper Cretaceous Campanian lacustrine deposits in northeastern China. The morphological features of this fossil scale are well-preserved and consistent with the structures found in ctenoid scales of extant fish species and display prominent ring ornamentation radiating outward from the central focus, with grooves intersecting the rings. A comparative analysis of the morphological characteristics between the fossil ctenoid scale and those well-studied extant fish Mugilidae allows us to explore the applicability of modern fishery biological research methods to the field of fossil scales. The scale length, scale width, the vertical distance from the focus to the apex of the scale, and the total number of radii have been measured. The age of the fish that possessed this ctenoid scale has been estimated by carefully counting the annuli, suggesting an age equal to or more than seven years. The distribution of growth rings on the scale potentially reflects the warm paleoclimatic condition and fish-friendly paleoenvironment prevalent during that period. This paper, moreover, serves as a notable application of fishery biological methods in the examination of fossil materials.
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Affiliation(s)
- Zhaoqing Liu
- College of Earth Sciences, Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, Changchun, Jilin Province, China
| | - Xiaobo Li
- College of Earth Sciences, Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, Changchun, Jilin Province, China
- Bioarchaeology Laboratory of Jilin University, Changchun, China
| | - Robert R. Reisz
- College of Earth Sciences, Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, Changchun, Jilin Province, China
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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2
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Maho T, Maho S, Bevitt JJ, Reisz RR. Size and shape heterodonty in the early Permian synapsid Mesenosaurus efremovi. J Anat 2024. [PMID: 38430000 DOI: 10.1111/joa.14034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 01/29/2024] [Accepted: 02/16/2024] [Indexed: 03/03/2024] Open
Abstract
Paleozoic synapsids represent the first chapter in the evolution of this large clade that includes mammals. These fascinating terrestrial vertebrates were the first amniotes to successfully adapt to a wide range of feeding strategies, reflected by their varied dental morphologies. Evolution of the marginal dentition on the mammalian side of amniotes is characterized by strong, size and shape heterodonty, with the late Permian therapsids showing heterodonty with the presence of incisiform, caniniform, and multicuspid molariform dentition. Rarity of available specimens has previously prevented detailed studies of dental anatomy and evolution in the initial chapter of synapsid evolution, when synapsids were able to evolve dentition for insectivory, herbivory, and carnivory. Numerous teeth, jaw elements, and skulls of the hypercarnivorous varanopid Mesenosaurus efremovi have been recently discovered in the cave systems near Richards Spur, Oklahoma, permitting the first detailed investigation of the dental anatomy of a Paleozoic tetrapod using multiple approaches, including morphometric and histological analyses. As a distant stem mammal, Mesenosaurus is the first member of this large and successful clade to exhibit a type of dental heterodonty that combines size and morphological (shape) variation of the tooth crowns. Here we present the first evidence of functional differentiation in the dentition of this early synapsid, with three distinct dental regions having diverse morphologies and functions. The quality and quantity of preserved materials has allowed us to identify the orientation and curvature of the carinae (cutting edges), and the variation and distribution of the ziphodonty (serrations) along the carinae. The shape-related heterodonty seen in this taxon may have contributed to this taxon's ability to be a successful mid-sized predator in the taxonomically diverse community of early Permian carnivores, but may have also extended the ecological resilience of this clade of mid-sized predators across major faunal and environmental transitions.
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Affiliation(s)
- Tea Maho
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
- Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, Changchun, Jilin, China
| | - Sigi Maho
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
- Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, Changchun, Jilin, China
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3
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Maho T, Reisz RR. Exceptionally rapid tooth development and ontogenetic changes in the feeding apparatus of the Komodo dragon. PLoS One 2024; 19:e0295002. [PMID: 38324523 PMCID: PMC10849390 DOI: 10.1371/journal.pone.0295002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 11/14/2023] [Indexed: 02/09/2024] Open
Abstract
Dental developmental and replacement patterns in extinct amniotes have attracted a lot of attention. Notable among these are Paleozoic predatory synapsids, but also Mesozoic theropod dinosaurs, well known for having true ziphodonty, strongly serrated carinae with dentine cores within an enamel cap. The Komodo dragon, Varanus komodoensis, is the only extant terrestrial vertebrate to exhibit true ziphodonty, making it an ideal model organism for gaining new insights into the life history and feeding behaviours of theropod dinosaurs and early synapsids. We undertook a comparative dental histological analysis of this extant apex predator in combination with computed tomography of intact skulls. This study allowed us to reconstruct the dental morphology, ontogeny, and replacement patterns in the largest living lizard with known feeding behaviour, and apply our findings to extinct taxa where the behaviour is largely unknown. We discovered through computed tomography that V. komodoensis maintains up to five replacement teeth per tooth position, while histological analysis showed an exceptionally rapid formation of new teeth, every 40 days. Additionally, a dramatic ontogenetic shift in the dental morphology of V. komodoensis was also discovered, likely related to changes in feeding preferences and habitat. The juveniles have fewer dental specializations, lack true ziphodonty, are arboreal and feed mostly on insects, whereas the adults have strongly developed ziphodonty and are terrestrial apex predators with defleshing feeding behaviour. In addition, we found evidence that the ziphodont teeth of V. komodoensis have true ampullae (interdental folds for strengthening the serrations), similar to those found only in theropod dinosaurs. Comparisons with other species of Varanus and successive outgroup taxa reveal a complex pattern of dental features and adaptations, including the evolution of snake-like tongue flicking used for foraging for prey. However, only the Komodo dragon exhibits this remarkable set of dental innovations and specializations among squamates.
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Affiliation(s)
- Tea Maho
- International Center of Future Science, Jilin University, Changchun, Jilin Province, China
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Robert R. Reisz
- International Center of Future Science, Jilin University, Changchun, Jilin Province, China
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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4
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Mooney ED, Maho T, Philp RP, Bevitt JJ, Reisz RR. Paleozoic cave system preserves oldest-known evidence of amniote skin. Curr Biol 2024; 34:417-426.e4. [PMID: 38215745 DOI: 10.1016/j.cub.2023.12.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/29/2023] [Accepted: 12/05/2023] [Indexed: 01/14/2024]
Abstract
The richest and most diverse assemblage of early terrestrial tetrapods is preserved within the infilled cave system of Richards Spur, Oklahoma (289-286 Mya1). Some of the oldest-known terrestrial amniotes2,3 are exquisitely preserved here because of early impregnation and encasement of organic material by oil-seep hydrocarbons within rapidly deposited clay-rich cave sediments under toxic anoxic conditions.4 This phenomenon has also afforded the preservation of exceedingly rare integumentary soft tissues, reported here, providing critical first evidence into the anatomical changes marking the transition from the aquatic and semiaquatic lifestyles of anamniotes to the fully terrestrial lifestyles of early amniotes. This is the first record of a skin-cast fossil (3D carbonization of the skin proper) from the Paleozoic Era and the earliest known occurrence of epidermal integumentary structures. We also report on several compression fossils (carbonized skin impressions), all demonstrating similar external morphologies to extant crocodiles. A variety of previously unknown ossifications, as well as what are likely palpebral ossifications of the deeper dermis layer of the skin, are also documented. These fossils also serve as invaluable references for paleontological reconstructions. Chromatographic analysis of extractable hydrocarbons from bone and cave samples indicates that the source rock is the Devonian age Woodford Shale. Hydrocarbons derived from ancient marine organisms interacting with geologically younger terrestrial vertebrates have therefore resulted in the oldest-known preservation of amniote skin proper.
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Affiliation(s)
- Ethan D Mooney
- Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, 2699 Qianjin Str., Changchun, Jilin Province 130012, China; Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga L5L1C6, Ontario, Canada.
| | - Tea Maho
- Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, 2699 Qianjin Str., Changchun, Jilin Province 130012, China; Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga L5L1C6, Ontario, Canada.
| | - R Paul Philp
- School of Geosciences, University of Oklahoma, 1000 Asp Avenue, Norman 73019, Oklahoma, USA
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New Illawarra Rd., Lucas Heights 2234, New South Wales, Australia
| | - Robert R Reisz
- Dinosaur Evolution Research Center, International Center of Future Science, Jilin University, 2699 Qianjin Str., Changchun, Jilin Province 130012, China; Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga L5L1C6, Ontario, Canada.
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5
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Rowe DCT, Bevitt JJ, Reisz RR. Skeletal anatomy of the early Permian parareptile Delorhynchus with new information provided by neutron tomography. PeerJ 2023; 11:e15935. [PMID: 37637171 PMCID: PMC10452630 DOI: 10.7717/peerj.15935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 07/31/2023] [Indexed: 08/29/2023] Open
Abstract
Detailed description of the holotype skeleton of Delorhynchus cifellii, made possible through the use of neutron tomography, has yielded important new information about the cranial and postcranial anatomy of this early Permian acleistorhinid parareptile. Hitherto unknown features of the skull include a sphenethmoid, paired epipterygoids and a complete neurocranium. In addition, the stapes has been exposed in three dimensions for the first time in an early parareptile. Postcranial material found in articulation with the skull in this holotype allows for the first detailed description of vertebrae, ribs, shoulder girdle and humerus of an acleistorhinid parareptile, allowing for a reevaluation of the phylogenetic relationships of this taxon with other acleistorhinids, and more broadly among parareptiles. Results show that Delorhynchus is recovered as the sister taxon of Colobomycter, and 'acleistorhinids' now include Lanthanosuchus.
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Affiliation(s)
- Dylan C. T. Rowe
- Department of Biology, University of Toronto, Mississauga, Mississauga, Ontario, Canada
- Dinosaur Evolution Research Center, Jilin University, Changchun, China
| | - Joseph J. Bevitt
- Australian Centre for Neutron Scanning, Australian Nuclear Science and Technology Organization, Sydney, New South Wales, Australia
| | - Robert R. Reisz
- Department of Biology, University of Toronto, Mississauga, Mississauga, Ontario, Canada
- Dinosaur Evolution Research Center, Jilin University, Changchun, China
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6
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Bazzana-Adams KD, Evans DC, Reisz RR. Neurosensory anatomy and function in Dimetrodon, the first terrestrial apex predator. iScience 2023; 26:106473. [PMID: 37096050 PMCID: PMC10122045 DOI: 10.1016/j.isci.2023.106473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 02/16/2023] [Accepted: 03/19/2023] [Indexed: 04/05/2023] Open
Abstract
Dimetrodon is among the most recognizable fossil taxa, as well as the earliest terrestrial amniote apex predator. The neuroanatomy and auditory abilities of Dimetrodon has long been the subject of interest, but palaeoneurological analyses have been limited by the lack of three-dimensional endocast data. The first virtual endocasts reveal a strongly flexed brain with enlarged floccular fossae and a surprisingly well-ossified bony labyrinth clearly preserving the semicircular canals, along with an undifferentiated vestibule and putative perilymphatic duct. This first detailed palaeoneurological reconstruction reveals potential adaptations for a predatory lifestyle and suggests Dimetrodon was able to hear a wider range of frequencies than anticipated, potentially being sensitive to frequencies equal to or higher than many extant sauropsids, despite lacking an impedance matching ear. Ancestral state reconstructions support the long-standing view of Dimetrodon as representative of the ancestral state for therapsids, while underscoring the importance of validating reconstructive analyses with fossil data.
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7
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Bazzana-Adams KD, Evans DC, Bevitt JJ, Reisz RR. Neurosensory anatomy and function in Seymouria. J Morphol 2023; 284:e21577. [PMID: 36921082 DOI: 10.1002/jmor.21577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/16/2023] [Accepted: 03/08/2023] [Indexed: 03/17/2023]
Abstract
Seymouria is among the best-known stem amniotes and holds an important phylogenetic position for discussions of amniote evolution. Previous work has focused primarily on the osteology of Seymouria, with recent interest turning to the application of computed tomography (CT) to study the internal features. We utilized neutron CT to reconstruct the first virtual cranial endocast and the first complete otic endocasts of Seymouria, revealing previously unrecognized details of its palaeoneuroanatomy. The brain and inner ear of Seymouria are largely plesiomorphic relative to later-diverging crown amniotes, showing no indication of increased encephalization or braincase ossification. Our results also clarify the plesiomorphic condition for carotid artery morphology in amniotes, with Seymouria showing a similar condition to basal members of both the synapsid and sauropsid lineages. The reconstructed neuroanatomy also indicates that Seymouria did not possess any particular neuroanatomical specializations, despite the probable presence of an impedance matching hearing system. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kayla D Bazzana-Adams
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada.,Department of Natural History, Royal Ontario Museum, Toronto, Canada
| | - David C Evans
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada.,Department of Natural History, Royal Ontario Museum, Toronto, Canada
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Canada.,International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin Province, China
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8
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Bazzana KD, Evans DC, Bevitt JJ, Reisz RR. Endocasts of the basal sauropsid Captorhinus reveal unexpected neurological diversity in early reptiles. Anat Rec (Hoboken) 2023; 306:552-563. [PMID: 36240106 DOI: 10.1002/ar.25100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 09/30/2022] [Accepted: 10/08/2022] [Indexed: 11/11/2022]
Abstract
Captorhinids are a group of Paleozoic amniotes that represents one of the earliest-diverging clades of eureptiles. Although captorhinids are one of the best-known and most well-studied clades of early amniotes, their palaeoneuroanatomy has gone largely unexamined. We utilized neutron computed tomography to study the virtual cranial and otic endocasts of two captorhinid specimens. The neurosensory anatomy of captorhinids shows a mixture of traits considered plesiomorphic for sauropsids (no expansions of the cerebrum or olfactory bulbs, low degree of encephalization, low ossification of the otic capsule) and those considered more derived, including moderate cephalic and pontine flexures and a dorsoventrally tall bony labyrinth. The inner ear clearly preserves the elliptical, sub-orthogonal canals and the short, rounded vestibule, along with an unusually enlarged lateral canal and a unique curvature of the posterior canal. The reconstructed neurosensory anatomy indicates that captorhinids were sensitive to slightly higher frequencies than many of their contemporaries, likely reflecting differences in body size across taxa, while the morphology of the maxillary canal suggests a simple, tubular condition as the plesiomorphic state for Sauropsida and contributes to the ongoing discussions regarding the phylogenetic placement of varanopids. This study represents the first detailed tomographic study of the brain and inner ear of any basal eureptile. The new data described here reveal that the neuroanatomy of early sauropsids is far more complex and diverse than previously anticipated, and provide impetus for further exploration of the palaeoneuroanatomy of early amniotes.
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Affiliation(s)
- Kayla D Bazzana
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
| | - David C Evans
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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9
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Maho T, Bevitt JJ, Reisz RR. New specimens of the early Permian apex predator Varanops brevirostris at Richards Spur, Oklahoma, with histological information about its growth pattern. PeerJ 2023; 11:e14898. [PMID: 36819993 PMCID: PMC9938655 DOI: 10.7717/peerj.14898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/24/2023] [Indexed: 02/17/2023] Open
Abstract
An articulated pelvic region and additional isolated material of Varanops brevirostris, which are indistinguishable from those of the generotype from the Cacops bonebed, demonstrate the presence of this large varanopid at the Richards Spur locality. The articulated specimen includes lumbar, sacral, and anterior caudal vertebrae, partial pelvis, femur, and proximal part of tibia, confirming the autapomorphies previously suggested for this species. These include the presence of distinct blade-like shapes of the neural spines in the sacral region, the presence of deeply excavated pubis, and the presence of a distinct transverse ridge on the ventral surface of the femur distal to the intertrochanteric fossa. It has also been found that the transverse ridges and grooves become larger during ontogeny since the juvenile specimen did not exhibit a well-developed ridge. Histological analysis of isolated limb bones and neutron computed tomography (nCT) of the articulated specimen indicate that the latter likely belonged to an adult individual. This is in contrast to the other varanopid at Richards Spur, the significantly smaller, more gracile predator Mesenosaurus efremovi, which also shows the presence of growth lines and the external fundamental system with an estimated minimum age of fourteen.
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Affiliation(s)
- Tea Maho
- University of Toronto, Mississauga, Ontario, Canada,International Centre of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
| | - Joseph J. Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Robert R. Reisz
- University of Toronto, Mississauga, Ontario, Canada,International Centre of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
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10
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Chiu CT, Cao JK, Wang PW, Wu YN, Lee YC, Jeng YR, Shieh DB, Reisz RR. Mammalian tooth enamel functional sophistication demonstrated by combined nanotribology and synchrotron radiation FTIR analyses. iScience 2022; 26:105679. [PMID: 36713260 PMCID: PMC9881047 DOI: 10.1016/j.isci.2022.105679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 09/28/2022] [Accepted: 11/22/2022] [Indexed: 12/28/2022] Open
Abstract
The teeth of limbed vertebrates used for capturing and processing food are composed of mineralized dentine covered by hypermineralized enamel, the hardest material organisms produce. Here, we combine scanning probe microscopy, depth sensing, and spectromicroscopy (SR-FTIR) to characterize the surface ultrastructural topography, nanotribology, and chemical compositions of mammal species with different dietary habits, including omnivorous humans. Our synergistic approach shows that enamel with greater surface hardness or thickness exhibited a more salient gradient feature from the tooth surface to the dentino-enamel junction (DEJ) one that corresponds to the in situ phosphate-to-amide ratio. This gradient feature of enamel covering softer dentine is the determining factor of the amazingly robust physical property of this unique biomaterial. It provides the ability to dissipate stress under loading and prevent mechanical failure. Evolutionary change in the biochemical composition and biomechanical properties of mammalian dentition is related to variations in the oral processing of different food materials.
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Affiliation(s)
- Chen-Tzu Chiu
- School of Dentistry and Institute of Oral Medicine, National Cheng Kung University, Tainan 701401, Taiwan
| | - Jyun-Kai Cao
- Department of Mechanical Engineering, National Chung Cheng University, Chia-Yi 62100, Taiwan
| | - Pei-Wen Wang
- School of Dentistry and Institute of Oral Medicine, National Cheng Kung University, Tainan 701401, Taiwan,Center of Applied Nanomedicine and Core Facility Center, National Cheng Kung University, Tainan 701401, Taiwan
| | - Ya-Na Wu
- School of Dentistry and Institute of Oral Medicine, National Cheng Kung University, Tainan 701401, Taiwan,iMANI Center of the National Core Facility for Biopharmaceuticals, National Science and Technology Concil, Taipei 106214, Taiwan
| | - Yao-Chang Lee
- Life Science Group, National Synchrotron Radiation Center, Hsinchu 30076, Taiwan,Department of Optics and Photonics, National Central University, Chung-Li 32001, Taiwan,Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yeau-Ren Jeng
- Department of Mechanical Engineering, National Chung Cheng University, Chia-Yi 62100, Taiwan,Department of Biomedical Engineering, National Cheng Kung University, Tainan 70101, Taiwan,Medical Device Innovation Center, National Cheng Kung University, Tainan 70101, Taiwan,Academy of Innovative Semiconductor and Sustainable Manufacturing, National Cheng Kung University, Tainan 70101, Taiwan,Corresponding author
| | - Dar-Bin Shieh
- School of Dentistry and Institute of Oral Medicine, National Cheng Kung University, Tainan 701401, Taiwan,Center of Applied Nanomedicine and Core Facility Center, National Cheng Kung University, Tainan 701401, Taiwan,iMANI Center of the National Core Facility for Biopharmaceuticals, National Science and Technology Concil, Taipei 106214, Taiwan,Department of Stomatology, National Cheng Kung University Hospital, Tainan 704302, Taiwan,Corresponding author
| | - Robert R. Reisz
- International Centre of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin 130012, China,Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada,Corresponding author
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11
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Mooney ED, Maho T, Bevitt JJ, Reisz RR. An intriguing new diapsid reptile with evidence of mandibulo-dental pathology from the early Permian of Oklahoma revealed by neutron tomography. PLoS One 2022; 17:e0276772. [PMID: 36449456 PMCID: PMC9710763 DOI: 10.1371/journal.pone.0276772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/08/2022] [Indexed: 12/02/2022] Open
Abstract
The initial stages of diapsid evolution, the clade that includes extant reptiles and the majority of extinct reptilian taxa, is surprisingly poorly known. Notwithstanding the hypothesis that varanopids are diapsids rather than synapsids, there are only four araeoscelidians and one neodiapsid present in the late Carboniferous and early Permian. Here we describe the fragmentary remains of a very unusual new amniote from the famous cave deposits near Richards Spur, Oklahoma, that we recognize as a diapsid reptile, readily distinguishable from all other early amniotes by the unique dentition and lower jaw anatomy. The teeth have an unusual reeding pattern on the crown (long parallel ridges with rounded surfaces), with some teeth posteriorly tilted and strongly recurved, while a ventral protuberance forms the anterior terminus of the dentary. Overall, the lower jaw is unusually slender with a flattened ventral surface formed by the dentary and splenial anteriorly and the angular in the mid-region. The presence of a very slender triradiate jugal revealed through computed tomography confirms the existence of a large lower temporal fenestra, while the medial edge of the maxilla and the anatomy of the palatine confirm the presence of a large suborbital fenestra. Computed tomography of this new taxon reveals maxillary innervation that is characteristically reptile, not synapsid. Although no other definitively identifiable skull roof elements exist, the suborbital fenestra borders preserved on the palatine and maxilla supports the hypothesis that this is a diapsid reptile. Interestingly, the right dentary shows evidence of pathology, a rarely reported occurrence in Paleozoic amniotes, with several empty tooth sockets filled by bone. This small predator with delicate subthecodont implanted dentition provides strong evidence that diapsid reptiles were already diversifying rapidly in the early Permian, but likely were relatively rare members of terrestrial vertebrate assemblages.
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Affiliation(s)
- Ethan D. Mooney
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin, Peoples Republic of China
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada
| | - Tea Maho
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin, Peoples Republic of China
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada
| | - Joseph J. Bevitt
- Australian Nuclear Science & Technology Organization, Australian Center Neutron Scattering, Lucas Heights, Sydney, New South Wales, Australia
| | - Robert R. Reisz
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin, Peoples Republic of China
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada
- * E-mail:
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12
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Maho T, Maho S, Scott D, Reisz RR. Permian hypercarnivore suggests dental complexity among early amniotes. Nat Commun 2022; 13:4882. [PMID: 35986022 PMCID: PMC9391490 DOI: 10.1038/s41467-022-32621-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/09/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractThe oldest known complex terrestrial vertebrate community included hypercarnivorous varanopids, a successful clade of amniotes with wide geographic and temporal distributions. Little is known about their dentition and feeding behaviour, but with the unprecedented number of specimens of the varanopid Mesenosaurus from cave deposits in Oklahoma, we show that it exhibited serrations on the tooth crowns, and exceptionally rapid rates of development and reduced longevity relative to other terrestrial amniotes. In contrast, the coeval large apex predator Dimetrodon greatly increased dental longevity by increasing thickness and massiveness, whereas herbivores greatly reduced tooth replacement rates and increased dental longevity. Insectivores and omnivores represented the primitive condition and maintained modest replacement rates and longevity. The varied patterns of dental development among these early terrestrial amniotes reveal a hidden aspect of dental complexity in the emerging diverse amniote community, very soon after their initial appearance in the fossil record.
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Maho T, Reisz RR. Dental anatomy and replacement patterns in the early Permian stem amniote, Seymouria. J Anat 2022; 241:628-634. [PMID: 35762030 DOI: 10.1111/joa.13715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/19/2022] [Accepted: 06/02/2022] [Indexed: 11/29/2022] Open
Abstract
The exquisite preservation of maxillary and mandibular fragments of Seymouria has allowed us to examine for the first time in detail the dental anatomy and patterns of development in this stem amniote. The results obtained through histological examination show that Seymouria has pleurodont implantation with ankylosis of the tooth to the labial side of the jawbone. The dentary and maxillary teeth exhibit similar dental characteristics, such as the attachment bone (alveolar bone) and cementum rising above the jawbone on the base of the tooth, and smooth carinae extending lingually toward the tooth apex. Additionally, the clear presence of plicidentine, infolding of dentine into the pulp cavity, was found within the tooth root extending into the tooth crown. Lastly, the tooth replacement pattern is alternating, illustrating that Seymouria retains the classic primitive condition for tetrapods, a pattern that is continued in amniotes. Our results provide an important basis for comparison with other stem amniotes and with amniotes.
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Affiliation(s)
- Tea Maho
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.,International Center of Future Science, Jilin University, Jilin Province, China
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.,International Center of Future Science, Jilin University, Jilin Province, China
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Bazzana KD, Evans DC, Bevitt JJ, Reisz RR. Neurosensory anatomy of Varanopidae and its implications for early synapsid evolution. J Anat 2022; 240:833-849. [PMID: 34775594 PMCID: PMC9005680 DOI: 10.1111/joa.13593] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 12/11/2022] Open
Abstract
Varanopids are a group of Palaeozoic terrestrial amniotes which represent one of the earliest-diverging groups of synapsids, but their palaeoneurology has gone largely unstudied and recent analyses have challenged their traditional placement within synapsids. We utilized computed tomography (CT) to study the virtual cranial and otic endocasts of six varanopids, including representative taxa of both mycterosaurines and varanodontines. Our results show that the varanopid brain is largely plesiomorphic, being tubular in shape and showing no expansion of the cerebrum or olfactory bulbs, but is distinct in showing highly expanded floccular fossae. The housing of the varanopid bony labyrinth is also distinct, in that the labyrinth is bounded almost entirely by the supraoccipital-opisthotic complex, with the prootic only bordering the ventral portion of the vestibule. The bony labyrinth is surprisingly well-ossified, clearly preserving the elliptical, sub-orthogonal canals, prominent ampullae, and the short, undifferentiated vestibule; this high degree of ossification is similar to that seen in therapsid synapsids and supports the traditional placement of varanopids within Synapsida. The enlarged anterior canal, together with the elliptical, orthogonal canals and enlarged floccular fossa, lend support for the fast head movements indicated by the inferred predatory feeding mode of varanopids. Reconstructed neurosensory anatomy indicates that varanopids may have a much lower-frequency hearing range compared to more derived synapsids, suggesting that, despite gaining some active predatory features, varanopids retain plesiomorphic hearing capabilities. As a whole, our data reveal that the neuroanatomy of pelycosaur-grade synapsids is far more complex than previously anticipated.
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Affiliation(s)
- Kayla D. Bazzana
- Department of BiologyUniversity of Toronto MississaugaMississaugaCanada
- Department of Natural HistoryRoyal Ontario MuseumTorontoCanada
| | - David C. Evans
- Department of Natural HistoryRoyal Ontario MuseumTorontoCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoCanada
| | - Joseph J. Bevitt
- Australian Centre for Neutron ScatteringAustralian Nuclear Science and Technology OrganisationLucas HeightsNew South WhalesAustralia
| | - Robert R. Reisz
- Department of BiologyUniversity of Toronto MississaugaMississaugaCanada
- International Center of Future ScienceDinosaur Evolution Research CenterJilin UniversityChangchunJilin ProvinceChina
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15
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MacDougall MJ, Seeger R, Gee B, Ponstein J, Jansen M, Scott D, Bevitt JJ, Reisz RR, Fröbisch J. Revised Description of the Early Permian Recumbirostran “Microsaur” Nannaroter mckinziei Based on New Fossil Material and Computed Tomographic Data. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.739316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The early Permian Richards Spur locality of Oklahoma has produced abundant material of numerous terrestrial fossil tetrapods, including various “microsaurs,” several of which are considered to belong to the clade Recumbirostra. We present a new partial skull of the recumbirostran “microsaur” Nannaroter mckinziei; through computed tomography (CT) analysis of both this new specimen and the holotype, we provide an updated description of the taxon. This new description provides novel information regarding several regions that could not be examined previously due to either being absent in the holotype or difficult to access. This includes missing and obscured aspects of the skull roof, braincase, lower jaw, and the palatal region. Furthermore, the new information obtained from this description was used to update phylogenetic character codings of Nannaroter, and a revised phylogenetic analysis was conducted. The results of this updated analysis are congruent with those of other recent phylogenetic analyses of recumbirostran “microsaurs.” This new information adds to the ever-growing body of early tetrapod CT data, which has been, and will continue to be, important in revealing details regarding early tetrapod anatomy, interrelationships, paleoecology, and evolution.
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Berman DS, Sumida SS, Henrici AC, Scott D, Reisz RR, Martens T. The Early Permian Bolosaurid Eudibamus cursoris: Earliest Reptile to Combine Parasagittal Stride and Digitigrade Posture During Quadrupedal and Bipedal Locomotion. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.674173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A comprehensive description of the holotype skeleton is presented here for the first time of the lower Permian (Artinskian) reptile Eudibamus cursoris from the Bromacker locality of Germany since the brief description of the holotype in 2000. The holotype is essentially complete and is the only known bolosaurid represented by a well-preserved articulated skeleton. Included in the description here is a superbly preserved, partial, articulated second specimen of E. cursoris discovered at the same locality that includes a short portion of the vertebral column associated with the pelvis and right hindlimb. Descriptions of the holotype and new specimen add substantially to features of the skull and postcranium that not only confirm a bolosaurid assignment, but also add significantly to an already long list of structural features supporting an ability unique among Paleozoic vertebrates to reach relatively high bipedal and quadrupedal running speeds employing a parasagittal stride and digitigrade stance with the limbs held in a near vertical posture. Structural differences between the two specimens are restricted to the tarsi and are attributed to different ontogenetic stages of ossification, with the holotype representing a more juvenile individual, and the larger second specimen representing a more mature animal.
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Pritchard AC, Sues HD, Scott D, Reisz RR. Osteology, relationships and functional morphology of Weigeltisaurus jaekeli (Diapsida, Weigeltisauridae) based on a complete skeleton from the Upper Permian Kupferschiefer of Germany. PeerJ 2021; 9:e11413. [PMID: 34055483 PMCID: PMC8141288 DOI: 10.7717/peerj.11413] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 04/15/2021] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Weigeltisauridae is a clade of small-bodied diapsids characterized by a horned cranial frill, slender trunk and limbs, and a patagium supported by elongated bony rods. Partial skeletons and fragments are definitively known only from upper Permian (Lopingian) rocks in England, Germany, Madagascar and Russia. Despite these discoveries, there have been few detailed descriptions of weigeltisaurid skeletons, and the homologies of many skeletal elements-especially the rods supporting the patagium-remain the subject of controversy. MATERIALS & METHODS Here, we provide a detailed description of a nearly complete skeleton of Weigeltisaurus jaekeli from the upper Permian (Lopingian: Wuchiapingian) Kupferschiefer of Lower Saxony, Germany. Briefly addressed by past authors, the skeleton preserves a nearly complete skull, postcranial axial skeleton, appendicular skeleton, and patagial supports. Through comparisons with extant and fossil diapsids, we examine the hypotheses for the homologies of the patagial rods. To examine the phylogenetic position of Weigeltisauridae and characterize the morphology of the clade, we integrate the material and other weigeltisaurids into a parsimony-based phylogenetic analysis focused on Permo-Triassic non-saurian Diapsida and early Sauria (61 taxa, 339 characters). RESULTS We recognize a number of intriguing anatomical features in the weigeltisaurid skeleton described here, including hollow horns on the post-temporal arch, lanceolate teeth in the posterior portion of the maxilla, the absence of a bony arch connecting the postorbital and squamosal bones, elongate and slender phalanges that resemble those of extant arboreal squamates, and patagial rods that are positioned superficial to the lateral one third of the gastral basket. Our phylogenetic study recovers a monophyletic Weigeltisauridae including Coelurosauravus elivensis, Weigeltisaurus jaekeli, and Rautiania spp. The clade is recovered as the sister taxon to Drepanosauromorpha outside of Sauria (=Lepidosauria + Archosauria). CONCLUSIONS Our anatomical observations and phylogenetic analysis show variety of plesiomorphic diapsid characters and apomorphies of Weigeltisauridae in the specimen described here. We corroborate the hypothesis that the patagial ossifications are dermal bones unrelated to the axial skeleton. The gliding apparatus of weigeltisaurids was constructed from dermal elements unknown in other known gliding diapsids. SMNK-PAL 2882 and other weigeltisaurid specimens highlight the high morphological disparity of Paleozoic diapsids already prior to their radiation in the early Mesozoic.
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Affiliation(s)
- Adam C. Pritchard
- Department of Paleontology, Virginia Museum of Natural History, Martinsville, Virginia, United States
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, United States
| | - Hans-Dieter Sues
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, United States
| | - Diane Scott
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Robert R. Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
- Dinosaur Evolution Research Centre and International Centre of Future Science, Jilin University, Changchun, China
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18
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Maddin HC, Piekarski N, Reisz RR, Hanken J. Development and evolution of the tetrapod skull-neck boundary. Biol Rev Camb Philos Soc 2020; 95:573-591. [PMID: 31912655 PMCID: PMC7318664 DOI: 10.1111/brv.12578] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 12/11/2019] [Accepted: 12/12/2019] [Indexed: 11/26/2022]
Abstract
The origin and evolution of the vertebrate skull have been topics of intense study for more than two centuries. Whereas early theories of skull origin, such as the influential vertebral theory, have been largely refuted with respect to the anterior (pre-otic) region of the skull, the posterior (post-otic) region is known to be derived from the anteriormost paraxial segments, i.e. the somites. Here we review the morphology and development of the occiput in both living and extinct tetrapods, taking into account revised knowledge of skull development by augmenting historical accounts with recent data. When occipital composition is evaluated relative to its position along the neural axis, and specifically to the hypoglossal nerve complex, much of the apparent interspecific variation in the location of the skull-neck boundary stabilizes in a phylogenetically informative way. Based on this criterion, three distinct conditions are identified in (i) frogs, (ii) salamanders and caecilians, and (iii) amniotes. The position of the posteriormost occipital segment relative to the hypoglossal nerve is key to understanding the evolution of the posterior limit of the skull. By using cranial foramina as osteological proxies of the hypoglossal nerve, a survey of fossil taxa reveals the amniote condition to be present at the base of Tetrapoda. This result challenges traditional theories of cranial evolution, which posit translocation of the occiput to a more posterior location in amniotes relative to lissamphibians (frogs, salamanders, caecilians), and instead supports the largely overlooked hypothesis that the reduced occiput in lissamphibians is secondarily derived. Recent advances in our understanding of the genetic basis of axial patterning and its regulation in amniotes support the hypothesis that the lissamphibian occipital form may have arisen as the product of a homeotic shift in segment fate from an amniote-like condition.
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Affiliation(s)
- Hillary C. Maddin
- Museum of Comparative ZoologyHarvard University, 26 Oxford StreetCambridgeMA02138U.S.A.
- Department of Earth SciencesCarleton University, 1125 Colonel By DriveOttawaOntarioK1S 5B6Canada
| | - Nadine Piekarski
- Museum of Comparative ZoologyHarvard University, 26 Oxford StreetCambridgeMA02138U.S.A.
| | - Robert R. Reisz
- Department of BiologyUniversity of Toronto Mississauga3359 Mississauga Road, MississaugaOntarioL5L 1C6Canada
| | - James Hanken
- Museum of Comparative ZoologyHarvard University, 26 Oxford StreetCambridgeMA02138U.S.A.
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19
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Snyder AJ, LeBlanc ARH, Jun C, Bevitt JJ, Reisz RR. Thecodont tooth attachment and replacement in bolosaurid parareptiles. PeerJ 2020; 8:e9168. [PMID: 32440377 PMCID: PMC7229766 DOI: 10.7717/peerj.9168] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 04/20/2020] [Indexed: 11/20/2022] Open
Abstract
Permian bolosaurid parareptiles are well-known for having complex tooth crowns and complete tooth rows in the jaws, in contrast to the comparatively simple teeth and frequent replacement gaps in all other Paleozoic amniotes. Analysis of the specialized dentition of the bolosaurid parareptiles Bolosaurus from North America and Belebey from Russia, utilizing a combination of histological and tomographic data, reveals unusual patterns of tooth development and replacement. The data confirm that bolosaurid teeth have thecodont implantation with deep roots, the oldest known such example among amniotes, and independently evolved among much younger archosauromorphs (including dinosaurs and crocodilians) and among synapsids (including mammals). High-resolution CT scans were able to detect the density boundary between the alveolar bone and the jawbone, as confirmed by histology, and revealed the location and size of developing replacement teeth in the pulp cavity of functional teeth. Evidence provided by the paratype dentary of Belebey chengi indicates that replacement teeth are present along the whole tooth row at slightly different stages of development, with the ontogenetically more developed teeth anteriorly, suggesting that tooth replacement was highly synchronized. CT data also show tooth replacement is directly related to the presence of lingual pits in the jaw, and that migration of tooth buds occurs initially close to these resorption pits to a position immediately below the functional tooth within its pulp cavity. The size and complex shape of the replacement teeth in the holotype of Bolosaurus grandis indicate that the replacement teeth can develop within the pulp cavity to an advanced stage while the previous generation remains functional for an extended time, reminiscent of the condition seen in other amniotes with occluding dentitions, including mammals.
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Affiliation(s)
- Adam J Snyder
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Aaron R H LeBlanc
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Chen Jun
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China.,Lab for Evolution of Past Life and Environment in Northeast Asia, Jilin University, Ministry of Education, Changchun, China
| | | | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada.,International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
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20
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Reisz RR, LeBlanc ARH, Maddin HC, Dudgeon TW, Scott D, Huang T, Chen J, Chen CM, Zhong S. Early Jurassic dinosaur fetal dental development and its significance for the evolution of sauropod dentition. Nat Commun 2020; 11:2240. [PMID: 32382025 PMCID: PMC7206009 DOI: 10.1038/s41467-020-16045-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 04/08/2020] [Indexed: 11/18/2022] Open
Abstract
Rare occurrences of dinosaurian embryos are punctuated by even rarer preservation of their development. Here we report on dental development in multiple embryos of the Early Jurassic Lufengosaurus from China, and compare these to patterns in a hatchling and adults. Histology and CT data show that dental formation and development occurred early in ontogeny, with several cycles of tooth development without root resorption occurring within a common crypt prior to hatching. This differs from the condition in hatchling and adult teeth of Lufengosaurus, and is reminiscent of the complex dentitions of some adult sauropods, suggesting that their derived dental systems likely evolved through paedomorphosis. Ontogenetic changes in successive generations of embryonic teeth of Lufengosaurus suggest that the pencil-like teeth in many sauropods also evolved via paedomorphosis, providing a mechanism for the convergent evolution of small, structurally simple teeth in giant diplodocoids and titanosaurids. Therefore, such developmental perturbations, more commonly associated with small vertebrates, were likely also essential events in sauropod evolution.
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Affiliation(s)
- Robert R Reisz
- Dinosaur Evolution Research Centre and International Centre of Future Science, Jilin University, Changchun, 130000, Jilin, China.
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada.
- National Chung Hsing University, Taichung, 40227, Taiwan.
| | - Aaron R H LeBlanc
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Hillary C Maddin
- Department of Earth Sciences, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Thomas W Dudgeon
- Department of Earth Sciences, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Diane Scott
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Timothy Huang
- Dinosaur Evolution Research Centre and International Centre of Future Science, Jilin University, Changchun, 130000, Jilin, China
- National Chung Hsing University, Taichung, 40227, Taiwan
| | - Jun Chen
- Dinosaur Evolution Research Centre and International Centre of Future Science, Jilin University, Changchun, 130000, Jilin, China
| | - Chuan-Mu Chen
- National Chung Hsing University, Taichung, 40227, Taiwan
| | - Shiming Zhong
- Chuxiong Prefectural Museum, Chuxiong, 675000, Yunnan, China
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21
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Bazzana KD, Gee BM, Bevitt JJ, Reisz RR. Postcranial anatomy and histology of Seymouria, and the terrestriality of seymouriamorphs. PeerJ 2020; 8:e8698. [PMID: 32195050 PMCID: PMC7069408 DOI: 10.7717/peerj.8698] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 02/06/2020] [Indexed: 12/30/2022] Open
Abstract
Seymouria is the best known of the seymouriamorphs, a group of Permo-Carboniferous reptiliomorphs with both terrestrial and aquatic taxa. The majority of research on Seymouria has focused on cranial anatomy, with few detailed descriptions or illustrations of the postcrania. We utilized neutron computed tomography (nCT) and histological sampling to provide updated, detailed figures that clarify details of the postcranial anatomy and to assess the development and histology of Seymouria through specimens from the early Permian Richards Spur locality. The correlation of morphological and histological data indicate rapid metamorphosis in this terrestrially capable stem amniote, with the youngest specimen being postmetamorphic despite being distinctly younger than premetamorphic individuals of Discosauriscus, the only other seymouriamorph to have been histologically sampled. The microanatomical data (e.g., semi-open medullary cavity) also substantiate the hypothesis that Seymouria was terrestrial based on interpretation of external features, although the persistence of a modestly developed medullary spongiosa in comparison to either Discosauriscus or to other co-occurring terrestrial tetrapods suggests additional nuances that require further exploration. In the absence of clearly recognizable postmetamorphic stages in several seymouriamorph taxa, it is difficult to determine the evolutionary trajectory of terrestriality within the clade. Our analysis provides the first histological characterization of the life history of Seymouria and highlights the need for further study of seymouriamorph ontogeny.
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Affiliation(s)
- Kayla D Bazzana
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada.,Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
| | - Bryan M Gee
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Whales, Australia
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada.,International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin Province, China
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22
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Gee BM, Reisz RR. A redescription of the late Carboniferous trematopid Actiobates peabodyi from Garnett, Kansas. Anat Rec (Hoboken) 2020; 303:2821-2838. [PMID: 32003550 DOI: 10.1002/ar.24381] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 12/12/2019] [Accepted: 01/04/2020] [Indexed: 12/11/2022]
Abstract
Dissorophoids are a diverse clade of predominantly Permo-Carboniferous temnospondyls with a wide geographic distribution and broad ecological diversity. Each of the various dissorophoid clades first appears in the late Carboniferous, but their records are relatively sparse and fragmentary compared to those of the early Permian when dissorophoids reach their peak diversity and distribution, particularly in terrestrial environments where they are by far the most taxonomically diverse clade of non-amniote tetrapods. This provides an impetus for further study of the late Carboniferous terrestrial dissorophoids in order to contextualize the early stages in the clade's radiation into terrestrial ecosystems. Here we present a redescription of the late Carboniferous trematopid Actiobates peabodyi from Kansas, USA, which is represented by a nearly complete skeleton and which represents the earliest occurrence of trematopids in North America. Only the skull was previously described, and the taxon has been largely overlooked in the context of early terrestrial dissorophoid evolution. Here, we provide an updated cranial description, the first postcranial description, and a discussion of the position of A. peabodyi in the context of olsoniform evolution. Our most significant finding is the characterization of postcranial anatomy that is highly similar to that of later trematopid taxa. This high degree of conservatism indicates that the earliest trematopids were already well adapted for terrestrial environments, and post-Carboniferous radiations of olsoniforms may be attributed to an expansion of the dryland terrestrial environments in which these taxa already thrived, rather than to novel acquisition of adaptive features later in the clade's evolution.
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Affiliation(s)
- Bryan M Gee
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada.,International Centre of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
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23
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Gee BM, Haridy Y, Reisz RR. Histological skeletochronology indicates developmental plasticity in the early Permian stem lissamphibian Doleserpeton annectens. Ecol Evol 2020; 10:2153-2169. [PMID: 32128146 PMCID: PMC7042763 DOI: 10.1002/ece3.6054] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 12/15/2022] Open
Abstract
Doleserpeton annectens is a small-bodied early Permian amphibamiform, a clade of temnospondyl amphibians regarded by many workers to be on the lissamphibian stem. Most studies of this taxon have focused solely on its anatomy, but further exploration of other aspects of its paleobiology, such as developmental patterns, is critical for a better understanding of the early evolutionary history of lissamphibians. Here, we present a histological analysis of growth patterns in D. annectens that utilizes 60 femora, the largest sample size for any Paleozoic tetrapod. We identified pervasive pairs of closely spaced lines of arrested growth (LAGs), a pattern that indicates a marked degree of climatic harshness and that would result in two cessations of growth within a presumed single year. We documented a wide degree of variation compared to previous temnospondyl skeletochronological studies, reflected in the poor correlation between size and inferred age, but this observation aligns closely with patterns observed in extant lissamphibians. Furthermore, sensitivity analyses conducted by subsampling our dataset at more typical sample sizes for paleontological studies produced a wide range of results. This includes biologically improbable results and exceptionally well-fit curves that demonstrate that low sample size can produce potentially misleading artifacts. We propose that the weak correlation between age and size represents developmental plasticity in D. annectens that typifies extant lissamphibians. Detection of these patterns is likely only possible with large sample sizes in extinct taxa, and low sample sizes can produce false, misleading results that warrant caution in drawing paleobiological interpretations from such samples.
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Affiliation(s)
- Bryan M. Gee
- Department of BiologyUniversity of Toronto MississaugaMississaugaONCanada
| | - Yara Haridy
- Leibniz‐Institut für Evolutions‐ und BiodiversitätsforschungMuseum für NaturkundeBerlinGermany
| | - Robert R. Reisz
- Department of BiologyUniversity of Toronto MississaugaMississaugaONCanada
- International Centre for Future ScienceDinosaur Evolution Research CenterJilin UniversityChangchunChina
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MacDougall MJ, Winge A, Ponstein J, Jansen M, Reisz RR, Fröbisch J. New information on the early Permian lanthanosuchoid Feeserpeton oklahomensis based on computed tomography. PeerJ 2019; 7:e7753. [PMID: 31687269 PMCID: PMC6825742 DOI: 10.7717/peerj.7753] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 08/26/2019] [Indexed: 11/23/2022] Open
Abstract
The cave deposits of the Lower Permian Richards Spur locality in Oklahoma, USA, have produced an incredible number of terrestrial tetrapod taxa, many of which are currently only known from this locality. One of the many recent taxa to be described from the locality was the small lanthanosuchoid parareptile Feeserpeton oklahomensis. Represented by a well-preserved, near complete skull, F. oklahomensis would have been a small predatory reptile, likely preying upon arthropods, and contributes to the extensive tetrapod fauna that was present at Richards Spur. New computed tomography data of the holotype and only specimen has allowed us to visualize and describe previously obscured and inaccessible anatomy of this taxon. These areas include the mandibular ramus, the palate, the sphenethmoid, the epipterygoids, and the braincase. Furthermore, this new anatomical information allowed formerly unknown character codings to be updated, thus we also performed new phylogenetic analyses that incorporated this new information. The results of these updated phylogenetic analyses are very similar to those of past studies, with F. oklahomensis being found as the sister taxon to all other lanthanosuchoids.
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Affiliation(s)
- Mark J MacDougall
- Museum für Naturkunde Leibniz-Institute für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Anika Winge
- Museum für Naturkunde Leibniz-Institute für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Jasper Ponstein
- Museum für Naturkunde Leibniz-Institute für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Maren Jansen
- Museum für Naturkunde Leibniz-Institute für Evolutions- und Biodiversitätsforschung, Berlin, Germany.,Museum für Naturkunde Magdeburg, Magdeburg, Germany
| | - Robert R Reisz
- University of Toronto Mississauga, Mississauga, ON, Canada
| | - Jörg Fröbisch
- Museum für Naturkunde Leibniz-Institute für Evolutions- und Biodiversitätsforschung, Berlin, Germany.,Humboldt-Universität zu Berlin, Berlin, Germany
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Maho S, Gee BM, Reisz RR. A new varanopid synapsid from the early Permian of Oklahoma and the evolutionary stasis in this clade. R Soc Open Sci 2019; 6:191297. [PMID: 31824730 PMCID: PMC6837192 DOI: 10.1098/rsos.191297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 09/24/2019] [Indexed: 06/10/2023]
Abstract
Varanopids are a basal clade of small- to medium-sized non-therapsid synapsids, whose range extends from the late Pennsylvanian to the late middle Permian, and are found in North America, Russia, Europe and South Africa. The greatest varanopid diversity is observed at the fossiliferous cave deposits near Richards Spur, Oklahoma, well known for the preservation of a complex early Permian upland community. Two previously described varanopids, Mycterosaurus and Varanops, are known only from fragmentary disarticulated material at Richards Spur. A third putative varanopid, Basicranodon fortsillensis, represented by a partial parasphenoid, has been synonymized with Mycterosaurus longiceps. This study reports on a new varanopid taxon, represented by substantially more complete material, including three nearly complete skulls. Such comprehensive cranial material allows for a detailed study of the taxon and its relationship to other varanopids. This new varanopid bears great morphological similarity to Mesenosaurus romeri from the middle Permian Mezen River Basin of northern Russia. Phylogenetic analysis recovers a sister relationship between this taxon and Me. romeri. This relationship, in conjunction with a detailed morphological comparison, supports the placement of this taxon within Mesenosaurus, as a new species, Me. efremovi. These results reveal an unexpected extension of the geographical and temporal range of Mesenosaurus, contributing to our understanding of varanopid dispersal. The extended persistence of this basal clade of predatory synapsids, underscored by the apparent evolutionary stasis of this genus, is unusual among Palaeozoic tetrapods. This phenomenon implies an exceptionally high degree of extended ecological resilience across major faunal and environmental transitions.
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Affiliation(s)
- Sigi Maho
- Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, CanadaL5L 1C6
| | - Bryan M. Gee
- Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, CanadaL5L 1C6
| | - Robert R. Reisz
- International Centre of Future Science, Jilin University, 2699 Qianjin Avenue, Changchun, Jilin Province, People's Republic of China
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Haridy Y, Gee BM, Witzmann F, Bevitt JJ, Reisz RR. Retention of fish-like odontode overgrowth in Permian tetrapod dentition supports outside-in theory of tooth origins. Biol Lett 2019; 15:20190514. [PMID: 31506034 DOI: 10.1098/rsbl.2019.0514] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Teeth are often thought of as structures that line the margins of the mouth; however, tooth-like structures called odontodes are commonly found on the dermal bones of many Palaeozoic vertebrates including early jawless fishes. 'Odontode' is a generalized term for all tooth-like dentine structures that have homologous tissues and development. This definition includes true teeth and the odontodes of early 'fishes', which have been recently examined to gain new insights into the still unresolved origin of teeth. Two leading hypotheses are frequently referenced in this debate: the 'outside-in' hypothesis, which posits that dermal odontodes evolutionarily migrate into the oral cavity, and the 'inside-out' hypothesis, which posits that teeth originated in the oropharyngeal cavity and then moved outwards into the oral cavity. Here, we show that, unlike the well-known one-to-one replacement patterns of marginal dentition, the palatal dentition of the early Permian tetrapods, including the dissorophoid amphibian Cacops and the early reptile Captorhinus, is overgrown by a new layer of bone to which the newest teeth are then attached. This same overgrowth pattern has been well documented in dermal and oral odontodes (i.e. teeth) of early fishes. We propose that this pattern represents the primitive condition for vertebrates and may even predate the origin of jaws. Therefore, this pattern crosses the fish-tetrapod transition, and the retention of this ancestral pattern in the palatal dentition of early terrestrial tetrapods provides strong support for the 'outside-in' hypothesis of tooth origins.
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Affiliation(s)
- Yara Haridy
- Department of Biology, University of Toronto Mississauga, Ontario, Canada.,Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Bryan M Gee
- Department of Biology, University of Toronto Mississauga, Ontario, Canada
| | - Florian Witzmann
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New South Wales, Australia
| | - Robert R Reisz
- International Center of Future Science, Dinosaur Evolution Research Centre, Jilin University, Changchun, People's Republic of China
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Haridy Y, Witzmann F, Asbach P, Reisz RR. Permian metabolic bone disease revealed by microCT: Paget's disease-like pathology in vertebrae of an early amniote. PLoS One 2019; 14:e0219662. [PMID: 31390345 PMCID: PMC6685605 DOI: 10.1371/journal.pone.0219662] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 06/29/2019] [Indexed: 01/22/2023] Open
Abstract
Bone remodeling is an essential physiological process in growth and healing. In modern systems deviations from normal bone physiology in the form of pathologies aid in the understanding of normal bone metabolism. Here we use external morphology and X-ray microtomography to diagnose and describe a metabolic bone disease in an amniote from the early Permian. The specimen consists of two fused tail vertebrae of a small varanopid from early Permian (289 million years old) cave deposits near Richards Spur, Oklahoma, USA. Inspection of the outer morphology reveals that the fusion encompasses the vertebral centra, zygopophyses and haemal arches, with the fusion zones distinctly swollen on the left side of the specimen. With visualization of its internal structure by microCT, this specimen is diagnosed as a complex metabolic bone disease. The radiological imaging suggests a pathologically high bone turnover rate, as shown by abnormal bone formation in some areas and increased bone resorption in others. This supports that the varanopid suffered from a metabolic bone disease similar to Paget’s disease of bone as seen in humans today, which is linked to both genetic and viral factors. This finding extends the occurrence of Paget-like disease to the early Permian, and–provided a viral component was present–would also be by far the oldest evidence of viral infection in the fossil record.
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Affiliation(s)
- Yara Haridy
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
- * E-mail:
| | - Florian Witzmann
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Patrick Asbach
- Institut für Radiologie, Charité—Universitätsmedizin Berlin, Berlin, Germany
| | - Robert R. Reisz
- International Center of Future Science, Dinosaur Evolution Research Centre, Jilin University, Changchun, China
- Department of Biology University of Toronto Mississauga, Mississauga, Ontario, Canada
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Reisz RR. A small caseid synapsid, Arisierpeton simplex gen. et sp. nov., from the early Permian of Oklahoma, with a discussion of synapsid diversity at the classic Richards Spur locality. PeerJ 2019; 7:e6615. [PMID: 30997285 PMCID: PMC6462398 DOI: 10.7717/peerj.6615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 02/12/2019] [Indexed: 11/20/2022] Open
Abstract
The fossil record of caseids, a clade of faunivorous to large herbivorous Permian synapsids, is unusual in having a poorly documented history. Although Kungurian caseids are common in the well-known continental deposits of North America, and the fossil record of the group extends into the middle Permian (Guadalupian), with the presence of the large caseid Ennatosaurus in the Mezen Basin faunal assemblage, only two other occurrences are known in older Permian age sediments. One is an undescribed caseid from the Bromacker Quarry in Germany, and the second is Oromycter from the lower Permian of Richards Spur, Oklahoma. The former is known from several articulated skeletons, but the latter is known only from a handful of skeletal elements, including elements of the snout and lower jaw, some phalanges, and a few vertebrae. Here the fragmentary tooth bearing elements and dorsal vertebrae of another small caseid from Richards Spur are described, with a discussion of its significance in the context of caseid evolution, and the continuously expanding faunal list and taxic diversity at this locality.
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Affiliation(s)
- Robert R Reisz
- International Centre of Future Science, Jilin University, Changchun, Jilin, China.,Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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29
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Abstract
Dissorophoidea, a group of temnospondyl tetrapods that first appear in the Late Carboniferous, is made up of two clades ⎼ Olsoniformes and Amphibamiformes (Branchiosauridae and Amphibamidae) ⎼ the latter of which is widely thought to have given rise to living amphibians (i.e., Lissamphibia). The lissamphibian braincase has a highly derived morphology with several secondarily lost elements; however, these losses have never been incorporated into phylogenetic analyses and thus the timing and nature of these evolutionary events remain unknown. Hindering research into this problem has been the lack of phylogenetic analyses of Dissorophoidea that includes both taxonomically dense sampling and specific characters to document changes in the braincase in the lineage leading to Lissamphibia. Here we build on a recent, broadly sampled dissorophoid phylogenetic analysis to visualize key events in the evolution of the lissamphibian braincase. Our ancestral character state reconstructions show a clear, step-wise trend towards reduction of braincase ossification leading to lissamphibians, including reduction of the sphenethmoid, loss of the basioccipital at the Amphibamiformes node, and further loss of both the basisphenoid and the hypoglossal nerve foramina at the Lissamphibia node. Our analysis confirms that the highly derived condition of the lissamphibian braincase is characterized by overall simplification in terms of the number and extent of chondrocranial ossifications.
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Affiliation(s)
- Jade B. Atkins
- Department of Earth Sciences, Carleton University, Ottawa, ON, Canada
- * E-mail:
| | - Robert R. Reisz
- Department of Biology, University of Toronto at Mississauga, Mississauga, ON, Canada
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
| | - Hillary C. Maddin
- Department of Earth Sciences, Carleton University, Ottawa, ON, Canada
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Gee BM, Bevitt JJ, Garbe U, Reisz RR. New material of the 'microsaur' Llistrofus from the cave deposits of Richards Spur, Oklahoma and the paleoecology of the Hapsidopareiidae. PeerJ 2019; 7:e6327. [PMID: 30701139 PMCID: PMC6348957 DOI: 10.7717/peerj.6327] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/17/2018] [Indexed: 12/20/2022] Open
Abstract
The Hapsidopareiidae is a group of “microsaurs” characterized by a substantial reduction of several elements in the cheek region that results in a prominent, enlarged temporal emargination. The clade comprises two markedly similar taxa from the early Permian of Oklahoma, Hapsidopareion lepton and Llistrofus pricei, which have been suggested to be synonymous by past workers. Llistrofus was previously known solely from the holotype found near Richards Spur, which consists of a dorsoventrally compressed skull in which the internal structures are difficult to characterize. Here, we present data from two new specimens of Llistrofus. This includes data collected through the use of neutron tomography, which revealed important new details of the palate and the neurocranium. Important questions within “Microsauria” related to the evolutionary transformations that likely occurred as part of the acquisition of the highly modified recumbirostran morphology for a fossorial ecology justify detailed reexamination of less well-studied taxa, such as Llistrofus. Although this study eliminates all but one of the previous features that differentiated Llistrofus and Hapsidopareion, the new data and redescription identify new features that justify the maintained separation of the two hapsidopareiids. Llistrofus possesses some of the adaptations for a fossorial lifestyle that have been identified in recumbirostrans but with a lesser degree of modification (e.g., reduced neurocranial ossification and mandibular modification). Incorporating the new data for Llistrofus into an existing phylogenetic matrix maintains the Hapsidopareiidae’s (Llistrofus + Hapsidopareion) position as the sister group to Recumbirostra. Given its phylogenetic position, we contextualize Llistrofus within the broader “microsaur” framework. Specifically, we propose that Llistrofus may have been fossorial but was probably incapable of active burrowing in the fashion of recumbirostrans, which had more consolidated and reinforced skulls. Llistrofus may represent an earlier stage in the step-wise acquisition of the derived recumbirostran morphology and paleoecology, furthering our understanding of the evolutionary history of “microsaurs.”
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Affiliation(s)
- Bryan M Gee
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Ulf Garbe
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.,International Centre of Future Science, Jilin University, Changchun, Jilin Province, China
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31
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Brink KS, MacDougall MJ, Reisz RR. Dimetrodon (Synapsida: Sphenacodontidae) from the cave system at Richards Spur, OK, USA, and a comparison of Early Permian-aged vertebrate paleoassemblages. Naturwissenschaften 2019; 106:2. [PMID: 30610457 DOI: 10.1007/s00114-018-1598-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/30/2018] [Accepted: 12/12/2018] [Indexed: 11/27/2022]
Abstract
The Early Permian Richards Spur locality is unique in preserving a highly diverse faunal assemblage in a cave system, composed of synapsids, reptiles, and anamniotes. However, the presence of Dimetrodon, the most common synapsid of Early Permian localities of the southwestern USA, has never been recorded from the site. Here, we describe for the first time the morphology and histology of a small neural spine with the distinctive figure-8 shape attributable to Dimetrodon. Additionally, histological analysis of previously described sphenacodontid teeth suggests the presence of a derived species of Dimetrodon at the Richards Spur locality. The presence of this derived synapsid, typical of the later occurring Kungurian localities of Texas and Oklahoma, is unexpected at the stratigraphically older Richards Spur locality. The cave system at Richards Spur preserves mainly basal synapsid taxa, including small caseid, varanopid, and sphenacodontid skeletal remains. The presence of a derived species of Dimetrodon suggests not only that this animal was more widespread than previously thought, but that there are different patterns of Early Permian synapsid evolution in different ecological settings.
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Affiliation(s)
- Kirstin S Brink
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1J7, Canada.,Department of Oral Health Sciences, Faculty of Dentistry, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Mark J MacDougall
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1J7, Canada.,Museum für Naturkunde Leibniz-Institute für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Robert R Reisz
- International Center for Future Science, Jilin University, Changchun, China.
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Chen J, LeBlanc ARH, Jin L, Huang T, Reisz RR. Tooth development, histology, and enamel microstructure in Changchunsaurus parvus: Implications for dental evolution in ornithopod dinosaurs. PLoS One 2018; 13:e0205206. [PMID: 30403689 PMCID: PMC6221265 DOI: 10.1371/journal.pone.0205206] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 09/20/2018] [Indexed: 11/24/2022] Open
Abstract
The great diversity of dinosaurian tooth shapes and sizes, and in particular, the amazing dental complexity in derived ornithischians has attracted a lot of attention. However, the evolution of dental batteries in hadrosaurids and ceratopsids is difficult to understand without a broader comparative framework. Here we describe tooth histology and development in the "middle" Cretaceous ornithischian dinosaur Changchunsaurus parvus, a small herbivore that has been characterized as an early ornithopod, or even as a more basal ornithischian. We use this taxon to show how a "typical" ornithischian dentition develops, copes with wear, and undergoes tooth replacement. Although in most respects the histological properties of their teeth are similar to those of other dinosaurs, we show that, as in other more derived ornithischians, in C. parvus the pulp chamber is not invaded fully by the newly developing replacement tooth until eruption is nearly complete. This allowed C. parvus to maintain an uninterrupted shearing surface along a single tooth row, while undergoing continuous tooth replacement. Our histological sections also show that the replacement foramina on the lingual surfaces of the jaws are likely the entry points for an externally placed dental lamina, a feature found in many other ornithischian dinosaurs. Surprisingly, our histological analysis also revealed the presence of wavy enamel, the phylogenetically earliest occurrence of this type of tissue. This contradicts previous interpretations that this peculiar type of enamel arose in association with more complex hadrosauroid dentitions. In view of its early appearance, we suggest that wavy enamel may have evolved in association with a shearing-type dentition in a roughly symmetrically-enameled crown, although its precise function still remains somewhat of a mystery.
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Affiliation(s)
- Jun Chen
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
- The Key-Lab for Evolution of Past Life and Environment in Northeast Asia, Ministry of Education, China, Changchun, China
| | - Aaron R. H. LeBlanc
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Liyong Jin
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
- The Key-Lab for Evolution of Past Life and Environment in Northeast Asia, Ministry of Education, China, Changchun, China
| | - Timothy Huang
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
| | - Robert R. Reisz
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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LeBlanc ARH, Brink KS, Whitney MR, Abdala F, Reisz RR. Dental ontogeny in extinct synapsids reveals a complex evolutionary history of the mammalian tooth attachment system. Proc Biol Sci 2018; 285:20181792. [PMID: 30404877 PMCID: PMC6235047 DOI: 10.1098/rspb.2018.1792] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 10/12/2018] [Indexed: 12/23/2022] Open
Abstract
The mammalian dentition is uniquely characterized by a combination of precise occlusion, permanent adult teeth and a unique tooth attachment system. Unlike the ankylosed teeth in most reptiles, mammal teeth are supported by a ligamentous tissue that suspends each tooth in its socket, providing flexible and compliant tooth attachment that prolongs the life of each tooth and maintains occlusal relationships. Here we investigate dental ontogeny through histological examination of a wide range of extinct synapsid lineages to assess whether the ligamentous tooth attachment system is unique to mammals and to determine how it evolved. This study shows for the first time that the ligamentous tooth attachment system is not unique to crown mammals within Synapsida, having arisen in several non-mammalian therapsid clades as a result of neoteny and progenesis in dental ontogeny. Mammalian tooth attachment is here re-interpreted as a paedomorphic condition relative to the ancestral synapsid form of tooth attachment.
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Affiliation(s)
- Aaron R H LeBlanc
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6
- Department of Biological Sciences, Faculty of Science, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
| | - Kirstin S Brink
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6
- Department of Oral Health Sciences, Faculty of Dentistry, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Megan R Whitney
- Department of Biology and Burke Museum, University of Washington, Seattle, WA, USA
| | - Fernando Abdala
- Unidad Ejecutora Lillo, Conicet, Tucumán, Argentina
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
- National Research Foundation, Centre of Excellence: Palaeosciences, Pretoria, South Africa
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6
- Institute of Oral Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan, Republic of China
- DERC, Jilin University, Changchun, Jilin Province, People's Republic of China
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LeBlanc ARH, MacDougall MJ, Haridy Y, Scott D, Reisz RR. Caudal autotomy as anti-predatory behaviour in Palaeozoic reptiles. Sci Rep 2018; 8:3328. [PMID: 29507301 PMCID: PMC5838224 DOI: 10.1038/s41598-018-21526-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 02/02/2018] [Indexed: 11/09/2022] Open
Abstract
Many lizards can drop a portion of their tail in response to an attack by a predator, a behaviour known as caudal autotomy. The capacity for intravertebral autotomy among modern reptiles suggests that it evolved in the lepidosaur branch of reptilian evolution, because no such vertebral features are known in turtles or crocodilians. Here we present the first detailed evidence of the oldest known case of caudal autotomy, found only among members of the Early Permian captorhinids, a group of ancient reptiles that diversified extensively and gained a near global distribution before the end-Permian mass extinction event of the Palaeozoic. Histological and SEM evidence show that these early reptiles were the first amniotes that could autotomize their tails, likely as an anti-predatory behaviour. As in modern iguanid lizards, smaller captorhinids were able to drop their tails as juveniles, presumably as a mechanism to evade a predator, whereas larger individuals may have gradually lost this ability. Caudal autotomy in captorhinid reptiles highlights the antiquity of this anti-predator behaviour in a small member of a terrestrial community composed predominantly of larger amphibian and synapsid predators.
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Affiliation(s)
- A R H LeBlanc
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada
- Department of Biological Sciences, University of Alberta, Alberta, T6G 2J5, Canada
| | - M J MacDougall
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada
| | - Y Haridy
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada
| | - D Scott
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada
| | - R R Reisz
- International Center of Future Science, Dinosaur Evolution Research Centre, Jilin University, Changchun, China.
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35
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Haridy Y, Macdougall MJ, Reisz RR. The lower jaw of the Early Permian parareptile Delorhynchus, first evidence of multiple denticulate coronoids in a reptile. Zool J Linn Soc 2017. [DOI: 10.1093/zoolinnean/zlx085] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Yara Haridy
- Department of Biology, University of Toronto Mississauga, Canada
| | | | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Canada
- Department of Optics and Photonics, National Central University, Taoyuan, Taiwan
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Haridy Y, LeBlanc ARH, Reisz RR. The Permian reptile Opisthodontosaurus carrolli: a model for acrodont tooth replacement and dental ontogeny. J Anat 2017; 232:371-382. [PMID: 29210080 DOI: 10.1111/joa.12754] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2017] [Indexed: 11/27/2022] Open
Abstract
Continuous tooth replacement is common for tetrapods, but some groups of acrodont lepidosaurs have lost the ability to replace their dentition (monophyodonty). Acrodonty, where the tooth attaches to the apex of the jawbone, is an unusual form of tooth attachment that has been associated with the highly autapomorphic condition of monophyodonty. Beyond Lepidosauria, very little is known about the relationship between acrodonty and monophyodonty in other amniotes. We test for this association with a detailed study of the dentition of Opisthodontosaurus, an unusual Early Permian captorhinid eureptile with acrodont dentition. We provide clear evidence, both histological and morphological, that there were regular tooth replacement events in the lower jaw of Opisthodontosaurus, similar to its captorhinid relatives. Thus, our study of the oldest known amniote with an acrodont dentition shows that acrodonty does not inhibit tooth replacement, and that many of the characteristics assigned to lepidosaurian acrodonty are actually highly derived features of lepidosaurs that have resulted secondarily from a lack of tooth replacement. In the context of reptilian dental evolution, we propose the retention of the simple definition of acrodonty, which only pertains to the relative position of the tooth at the apex of the jaw, where the jaw possesses equal lingual and labial walls. This definition of implantation therefore focuses solely on the spatial relationship between the tooth and the jawbone, and separates this relationship from tooth development and replacement.
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Affiliation(s)
- Yara Haridy
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Aaron R H LeBlanc
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.,Department of Optics and Photonics, National Central University, Jhongli, Taoyuan, Taiwan
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Brink KS, Chen YC, Wu YN, Liu WM, Shieh DB, Huang TD, Sun CK, Reisz RR. Dietary adaptions in the ultrastructure of dinosaur dentine. J R Soc Interface 2017; 13:rsif.2016.0626. [PMID: 27974573 DOI: 10.1098/rsif.2016.0626] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 11/17/2016] [Indexed: 02/01/2023] Open
Abstract
Teeth are key to understanding the feeding ecology of both extant and extinct vertebrates. Recent studies have highlighted the previously unrecognized complexity of dinosaur dentitions and how specific tooth tissues and tooth shapes differ between taxa with different diets. However, it is unknown how the ultrastructure of these tooth tissues contributes to the differences in feeding style between taxa. In this study, we use third harmonic generation microscopy and scanning electron microscopy to examine the ultrastructure of the dentine in herbivorous and carnivorous dinosaurs to understand how the structure of this tissue contributes to the overall utility of the tooth. Morphometric analyses of dentinal tubule diameter, density and branching rates reveal a strong signal for dietary preferences, with herbivorous saurischian and ornithischian dinosaurs consistently having higher dentinal tubule density than their carnivorous relatives. We hypothesize that this relates to the hardness of the dentine, where herbivorous taxa have dentine that is more resistant to breakage and wear at the dentine-enamel junction than carnivorous taxa. This study advocates the detailed study of dentine and the use of advanced microscopy techniques to understand the evolution of dentition and feeding ecology in extinct vertebrates.
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Affiliation(s)
- Kirstin S Brink
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5 L 1C6
| | - Yu-Cheng Chen
- Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Ya-Na Wu
- Institute of Oral Medicine, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan, Republic of China
| | - Wei-Min Liu
- Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Dar-Bin Shieh
- Institute of Oral Medicine, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan, Republic of China
| | - Timothy D Huang
- Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin Province 130012, People's Republic of China.,National Chung Hsing University, Taichung 402, Taiwan, Republic of China
| | - Chi-Kuang Sun
- Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan, Republic of China.,Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan, Republic of China.,Graduate Institute of Biomedical Electronics and Bioinformatics and Center for Optoelectronic Medicine, National Taiwan University, Taipei 10617, Taiwan, Republic of China.,Institute of Physics and Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan, Republic of China
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5 L 1C6.,Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin Province 130012, People's Republic of China.,National Chung Hsing University, Taichung 402, Taiwan, Republic of China.,Department of Optics and Photonics, National Central University, Jhongli, Taoyuan 32001, Taiwan, Republic of China
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Gee BM, Haridy Y, Reisz RR. Histological characterization of denticulate palatal plates in an Early Permian dissorophoid. PeerJ 2017; 5:e3727. [PMID: 28848692 PMCID: PMC5571816 DOI: 10.7717/peerj.3727] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 08/02/2017] [Indexed: 11/24/2022] Open
Abstract
Denticles are small, tooth-like protrusions that are commonly found on the palate of early tetrapods. Despite their widespread taxonomic occurrence and similar external morphology to marginal teeth, it has not been rigorously tested whether denticles are structurally homologous to true teeth with features such as a pulp cavity, dentine, and enamel, or if they are bony, tooth-like protrusions. Additionally, the denticles are known to occur not only on the palatal bones but also on a mosaic of small palatal plates that is thought to have covered the interpterygoid vacuities of temnospondyls through implantation in a soft tissue covering; however, these plates have never been examined beyond a simple description of their position and external morphology. Accordingly, we performed a histological analysis of these denticulate palatal plates in a dissorophoid temnospondyl in order to characterize their microanatomy and histology. The dentition on these palatal plates has been found to be homologous with true teeth on the basis of both external morphology and histological data through the identification of features such as enamel and a pulp cavity surrounded by dentine. In addition, patterns of tooth replacement and ankylosis support the hypothesis of structural homology between these tiny teeth on the palatal plates and the much larger marginal dentition. We also provide the first histological characterization of the palatal plates, including documentation of abundant Sharpey’s fibres that provide a direct line of evidence to support the hypothesis of soft tissue implantation. Finally, we conducted a survey of the literature to determine the taxonomic distribution of these plates within Temnospondyli, providing a broader context for the presence of palatal plates and illustrating the importance of maintaining consistency in nomenclature.
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Affiliation(s)
- Bryan M Gee
- Department of Biology, University of Toronto Mississauga, Ontario, Canada
| | - Yara Haridy
- Department of Biology, University of Toronto Mississauga, Ontario, Canada
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Ontario, Canada
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Macdougall MJ, Scott D, Modesto SP, Williams SA, Reisz RR. New material of the reptile Colobomycter pholeter (Parareptilia: Lanthanosuchoidea) and the diversity of reptiles during the Early Permian (Cisuralian). Zool J Linn Soc 2017. [DOI: 10.1093/zoolinnean/zlw012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Lee YC, Chiang CC, Huang PY, Chung CY, Huang TD, Wang CC, Chen CI, Chang RS, Liao CH, Reisz RR. Evidence of preserved collagen in an Early Jurassic sauropodomorph dinosaur revealed by synchrotron FTIR microspectroscopy. Nat Commun 2017; 8:14220. [PMID: 28140389 PMCID: PMC5290320 DOI: 10.1038/ncomms14220] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 12/09/2016] [Indexed: 12/29/2022] Open
Abstract
Fossilized organic remains are important sources of information because they provide a unique form of biological and evolutionary information, and have the long-term potential for genomic explorations. Here we report evidence of protein preservation in a terrestrial vertebrate found inside the vascular canals of a rib of a 195-million-year-old sauropodomorph dinosaur, where blood vessels and nerves would normally have been present in the living organism. The in situ synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectra exhibit the characteristic infrared absorption bands for amide A and B, amide I, II and III of collagen. Aggregated haematite particles (α-Fe2O3) about 6∼8 μm in diameter are also identified inside the vascular canals using confocal Raman microscopy, where the organic remains were preserved. We propose that these particles likely had a crucial role in the preservation of the proteins, and may be remnants partially contributed from haemoglobin and other iron-rich proteins from the original blood.
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Affiliation(s)
- Yao-Chang Lee
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Department of Optics and Photonics, National Central University, Chung-Li 32001, Taiwan
| | | | - Pei-Yu Huang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chao-Yu Chung
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Timothy D. Huang
- Department of Optics and Photonics, National Central University, Chung-Li 32001, Taiwan
- Dinosaur Evolution Research Center of Jilin University, Changchun, Jilin 130012, China
- College of Life Sciences, National Chung Hsing University, Taichung 400, Taiwan
| | - Chun-Chieh Wang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Ching-Iue Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Rong-Seng Chang
- Department of Optics and Photonics, National Central University, Chung-Li 32001, Taiwan
| | | | - Robert R. Reisz
- Department of Optics and Photonics, National Central University, Chung-Li 32001, Taiwan
- Dinosaur Evolution Research Center of Jilin University, Changchun, Jilin 130012, China
- College of Life Sciences, National Chung Hsing University, Taichung 400, Taiwan
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6
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Haridy Y, Macdougall MJ, Scott D, Reisz RR. Ontogenetic Change in the Temporal Region of the Early Permian Parareptile Delorhynchus cifellii and the Implications for Closure of the Temporal Fenestra in Amniotes. PLoS One 2016; 11:e0166819. [PMID: 27907071 PMCID: PMC5132164 DOI: 10.1371/journal.pone.0166819] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/05/2016] [Indexed: 11/19/2022] Open
Abstract
A juvenile specimen of Delorhynchus cifellii, collected from the Early Permian fissure-fill deposits of Richards Spur, Oklahoma, permits the first detailed study of cranial ontogeny in this parareptile. The specimen, consisting of a partially articulated skull and mandible, exhibits several features that identify it as juvenile. The dermal tuberosities that ornament the dorsal side and lateral edges of the largest skull of D. cifellii specimens, are less prominent in the intermediate sized holotype, and are absent in the new specimen. This indicates that the new specimen represents an earlier ontogenetic stage than all previously described members of this species. In addition, the incomplete interdigitation of the sutures, most notably along the fronto-nasal contact, plus the proportionally larger sizes of the orbit and temporal fenestrae further support an early ontogenetic stage for this specimen. Comparisons between this juvenile and previously described specimens reveal that the size and shape of the temporal fenestra in Delorhynchus appear to vary through ontogeny, due to changes in the shape and size of the bordering cranial elements. The jugal of the juvenile specimen is tri-radiate and similar in outline with those found in other amniotes with temporal fenestrae. The available growth series of D. cifellii shows that the jugal gradually becomes a more robust, tetra-radiate element, as the proportionate size of the temporal fenestra is reduced. Ontogenetic changes of other elements that form the border of the fenestra also contribute to its reduction. This growth series provides valuable new information regarding the ontogenetic trajectory of the temporal fenestra in a Palaeozoic reptile, which may be applicable to the evolutionary event of loss of temporal fenestration in other amniotes.
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Affiliation(s)
- Yara Haridy
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
- * E-mail:
| | - Mark J. Macdougall
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Diane Scott
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Robert R. Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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LeBlanc ARH, Reisz RR, Evans DC, Bailleul AM. Ontogeny reveals function and evolution of the hadrosaurid dinosaur dental battery. BMC Evol Biol 2016; 16:152. [PMID: 27465802 PMCID: PMC4964017 DOI: 10.1186/s12862-016-0721-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/13/2016] [Indexed: 12/04/2022] Open
Abstract
Background Hadrosaurid dinosaurs, dominant Late Cretaceous herbivores, possessed complex dental batteries with up to 300 teeth in each jaw ramus. Despite extensive interest in the adaptive significance of the dental battery, surprisingly little is known about how the battery evolved from the ancestral dinosaurian dentition, or how it functioned in the living organism. We undertook the first comprehensive, tissue-level study of dental ontogeny in hadrosaurids using several intact maxillary and dentary batteries and compared them to sections of other archosaurs and mammals. We used these comparisons to pinpoint shifts in the ancestral reptilian pattern of tooth ontogeny that allowed hadrosaurids to form complex dental batteries. Results Comparisons of hadrosaurid dental ontogeny with that of other amniotes reveals that the ability to halt normal tooth replacement and functionalize the tooth root into the occlusal surface was key to the evolution of dental batteries. The retention of older generations of teeth was driven by acceleration in the timing and rate of dental tissue formation. The hadrosaurid dental battery is a highly modified form of the typical dinosaurian gomphosis with a unique tooth-to-tooth attachment that permitted constant and perfectly timed tooth eruption along the whole battery. Conclusions We demonstrate that each battery was a highly dynamic, integrated matrix of living replacement and, remarkably, dead grinding teeth connected by a network of ligaments that permitted fine scale flexibility within the battery. The hadrosaurid dental battery, the most complex in vertebrate evolution, conforms to a surprisingly simple evolutionary model in which ancestral reptilian tissue types were redeployed in a unique manner. The hadrosaurid dental battery thus allows us to follow in great detail the development and extended life history of a particularly complex food processing system, providing novel insights into how tooth development can be altered to produce complex dentitions, the likes of which do not exist in any living vertebrate. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0721-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aaron R H LeBlanc
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada.
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada.,Department of Optics and Photonics, National Central University, Jhongli City, Taoyuan, 32001, Taiwan
| | - David C Evans
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, Canada
| | - Alida M Bailleul
- Department of Pathology and Anatomical Sciences, Integrative Anatomy, University of Missouri, Columbia, MO, 65201, USA
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Brocklehurst N, Reisz RR, Fernandez V, Fröbisch J. A Re-Description of 'Mycterosaurus' smithae, an Early Permian Eothyridid, and Its Impact on the Phylogeny of Pelycosaurian-Grade Synapsids. PLoS One 2016; 11:e0156810. [PMID: 27333277 PMCID: PMC4917111 DOI: 10.1371/journal.pone.0156810] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/18/2016] [Indexed: 11/18/2022] Open
Abstract
'Mycterosaurus' smithae, from the Cisuralian (early Permian) of Colorado, was first described in 1965 as a second species of the genus Mycterosaurus. While the type species of this genus, M. longiceps, has been shown by multiple cladistic analyses to belong to the basal synapsid family Varanopidae, 'M.' smithae has been largely ignored since its original description. Additional preparation and synchrotron scanning has revealed new significant information that supports the assignment of this species to a new genus: Vaughnictis gen. nov. Vaughnictis lacks many of the characteristics of mycterosaurines and varanopids in general: it lacks the slender femur, the linguo-labially compressed and strongly recurved teeth, and the lateral boss on the postorbital characteristic of this family. Instead, it possesses coronoid teeth, a large supratemporal, and a large pineal foramen positioned midway along the length of the parietal, features that support its assignment to Eothyrididae. Moreover, the postcranium shares many characters with the eothyridid Oedaleops. An expanded version of a recently published phylogenetic analysis of pelycosaurian-grade synapsids positions Vaughnictis as the sister taxon of Eothyris within the clade Eothyrididae. The addition of data on the postcranium of eothyridids and the inclusion of the recently-described basal caseid Eocasea confirms the recently-disputed position of caseasaurs as the most basal synapsids. As the parsimony analysis produced low support values and a lack of resolution due to missing data, additional analyses were undertaken using Bayesian and Implied Weights methods, which produced better resolution and relationships with higher support values. While the results are similar, alternative positions for the enigmatic Moscovian age (Carboniferous) synapsid Echinerpeton are suggested by Bayesian analysis; the parsimony analysis found it to be an ophiacodontid, while the Bayesian and Implied Weights analysis found it to be the sister to the Sphenacomorpha.
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Affiliation(s)
- Neil Brocklehurst
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, D-10115, Berlin, Germany
| | - Robert R. Reisz
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, L5L 1C6, Canada
| | - Vincent Fernandez
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Jörg Fröbisch
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, D-10115, Berlin, Germany
- Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 110, Berlin, D-10115, Germany
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Fong RK, LeBlanc AR, Berman DS, Reisz RR. Dental histology ofCoelophysis bauriand the evolution of tooth attachment tissues in early dinosaurs. J Morphol 2016; 277:916-24. [DOI: 10.1002/jmor.20545] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/16/2016] [Accepted: 03/25/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Raymond K.M. Fong
- Department of Biology; University of Toronto; Mississauga Ontario L5L 1C6 Canada
| | - Aaron R.H. LeBlanc
- Department of Biology; University of Toronto; Mississauga Ontario L5L 1C6 Canada
| | - David S. Berman
- Vertebrate Paleontology, Carnegie Museum of Natural History; Pittsburgh Pennsylvania
| | - Robert R. Reisz
- Department of Biology; University of Toronto; Mississauga Ontario L5L 1C6 Canada
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45
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LeBlanc ARH, Reisz RR, Brink KS, Abdala F. Cover Image. J Clin Periodontol 2016. [DOI: 10.1111/jcpe.12563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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46
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LeBlanc ARH, Reisz RR, Brink KS, Abdala F. Mineralized periodontia in extinct relatives of mammals shed light on the evolutionary history of mineral homeostasis in periodontal tissue maintenance. J Clin Periodontol 2016; 43:323-32. [DOI: 10.1111/jcpe.12508] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Aaron R. H. LeBlanc
- Department of Biology; University of Toronto Mississauga; Mississauga ON Canada
| | - Robert R. Reisz
- Department of Biology; University of Toronto Mississauga; Mississauga ON Canada
- Institute of Oral Medicine; College of Medicine; National Cheng Kung University; Tainan Taiwan
| | - Kirstin S. Brink
- Department of Oral Health Sciences; Faculty of Dentistry; Life Sciences Institute; University of British Columbia; Vancouver BC Canada
| | - Fernando Abdala
- Evolutionary Studies Institute and School of Geosciences; University of the Witwatersrand; Johannesburg South Africa
- National Research Foundation; Centre of Excellence: Palaeosciences; Pretoria South Africa
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Wang CC, Song YF, Song SR, Ji Q, Chiang CC, Meng Q, Li H, Hsiao K, Lu YC, Shew BY, Huang T, Reisz RR. Evolution and Function of Dinosaur Teeth at Ultramicrostructural Level Revealed Using Synchrotron Transmission X-ray Microscopy. Sci Rep 2015; 5:15202. [PMID: 26512629 PMCID: PMC4625602 DOI: 10.1038/srep15202] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/21/2015] [Indexed: 11/09/2022] Open
Abstract
The relationship between tooth form and dietary preference is a crucial issue in vertebrate evolution. However, the mechanical properties of a tooth are influenced not only by its shape but also by its internal structure. Here, we use synchrotron transmission X-ray microscopy to examine the internal microstructures of multiple dinosaur teeth within a phylogenetic framework. We found that the internal microstructures of saurischian teeth are very different from advanced ornithischian teeth, reflecting differences in dental developmental strategies. The three-tissue composition (enamel-mantle dentin-bulk dentin) near the dentinoenamel junction (DEJ) in saurischian teeth represents the primitive condition of dinosaur teeth. Mantle dentin, greatly reduced or absent from DEJ in derived ornithischian teeth, is a key difference between Saurischia and Ornithischia. This may be related to the derived herbivorous feeding behavior of ornithischians, but interestingly, it is still retained in the herbivorous saurischian sauropods. The protective functions of mantle dentin with porous microstructures between enamel and bulk dentin inside typical saurischian teeth are also discussed using finite-element analysis method. Evolution of the dental modifications in ornithischian dinosaurs, with the absence of mantle dentin, may be related to changes in enamel characteristics with enamel spindles extending through the DEJ.
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Affiliation(s)
- Chun-Chieh Wang
- National Synchrotron Radiation Research Center, 30076 Hsinchu, Taiwan
| | - Yen-Fang Song
- National Synchrotron Radiation Research Center, 30076 Hsinchu, Taiwan
| | - Sheng-Rong Song
- Department of Geosciences, National Taiwan University, 10617 Taipei, Taiwan
| | - Qiang Ji
- Institute of Geology, Chinese Academy of Geological Sciences, 100037 Beijing, China
| | | | - Qingjin Meng
- Beijing Museum of Natural History, 100050 Beijing, China
| | - Haibing Li
- Institute of Geology, Chinese Academy of Geological Sciences, 100037 Beijing, China
| | - Kiko Hsiao
- Department of Geology, Chinese Culture University, 11114 Taipei, Taiwan
| | - Yi-Chia Lu
- Department of Geosciences, National Taiwan University, 10617 Taipei, Taiwan
| | - Bor-Yuan Shew
- National Synchrotron Radiation Research Center, 30076 Hsinchu, Taiwan
| | - Timothy Huang
- Institute of Genomics and Bioinformatics, National Chung Hsing University, 402 Taichung, Taiwan.,Department of Optics and Photonics, National Central University, 32001 Tauyuan, Taiwan
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada.,Department of Optics and Photonics, National Central University, 32001 Tauyuan, Taiwan
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Abstract
Amniotes, tetrapods that evolved the cleidoic egg and thus independence from aquatic larval stages, appeared ca 314 Ma during the Coal Age. The rapid diversification of amniotes and other tetrapods over the course of the Late Carboniferous period was recently attributed to the fragmentation of coal-swamp rainforests ca 307 Ma. However, the amniote fossil record during the Carboniferous is relatively sparse, with ca 33% of the diversity represented by single specimens for each species. We describe here a new species of reptilian amniote that was collected from uppermost Carboniferous rocks of Prince Edward Island, Canada. Erpetonyx arsenaultorum gen. et sp. nov. is a new parareptile distinguished by 29 presacral vertebrae and autapomorphies of the carpus. Phylogenetic analyses of parareptiles reveal E. arsenaultorum as the closest relative of bolosaurids. Stratigraphic calibration of our results indicates that parareptiles began their evolutionary radiation before the close of the Carboniferous Period, and that the diversity of end-Carboniferous reptiles is 80% greater than suggested by previous work. Latest Carboniferous reptiles were still half as diverse as synapsid amniotes, a disparity that may be attributable to preservational biases, to collecting biases, to the origin of herbivory in tetrapods or any combination of these factors.
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Affiliation(s)
- Sean P Modesto
- Department of Biology, Cape Breton University, Sydney, Nova Scotia, Canada B1P 6L2
| | - Diane M Scott
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6
| | - Mark J MacDougall
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6
| | - Hans-Dieter Sues
- National Museum of Natural History, Smithsonian Institution, MRC 121, PO Box 37012, Washington, DC 20013-7012, USA
| | - David C Evans
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada
| | - Robert R Reisz
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6
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Chen YC, Lee SY, Wu Y, Brink K, Shieh DB, Huang TD, Reisz RR, Sun CK. Third-harmonic generation microscopy reveals dental anatomy in ancient fossils. Opt Lett 2015; 40:1354-7. [PMID: 25831331 DOI: 10.1364/ol.40.001354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Fossil teeth are primary tools in the study of vertebrate evolution, but standard imaging modalities have not been capable of providing high-quality images in dentin, the main component of teeth, owing to small refractive index differences in the fossilized dentin. Our first attempt to use third-harmonic generation (THG) microscopy in fossil teeth has yielded significant submicrometer level anatomy, with an unexpectedly strong signal contrasting fossilized tubules from the surrounding dentin. Comparison between fossilized and extant teeth of crocodilians reveals a consistent evolutionary signature through time, indicating the great significance of THG microscopy in the evolutionary studies of dental anatomy in fossil teeth.
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LeBlanc ARH, Reisz RR. New postcranial material of the early caseid Casea broilii Williston, 1910 (Synapsida: Caseidae) with a review of the evolution of the sacrum in Paleozoic non-mammalian synapsids. PLoS One 2014; 9:e115734. [PMID: 25545624 PMCID: PMC4278720 DOI: 10.1371/journal.pone.0115734] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/01/2014] [Indexed: 11/19/2022] Open
Abstract
Here we use the description of a new specimen of the small caseid synapsid Casea broilii that preserves the sacral, pelvic and hind limb regions in great detail and in three dimensions, as a unique opportunity to reevaluate the early stages in the evolution of the sacrum in the lineage that led to mammals. We place this new material in the context of sacral evolution in early caseid synapsids and conclude that the transition from two to three sacral vertebrae occurred in small-bodied species, suggesting that it was not an adaptation to heavy weight bearing. Furthermore, we compare descriptions of sacral anatomy among known early synapsids, including caseids, ophiacodontids, edaphosaurids, varanopids, and sphenacodontians and review sacral evolution in early synapsids. Based on the descriptions of new species of caseids, edaphosaurids, and varanopids over the past several decades, it is clear that a sacrum consisting of three vertebrae evolved independently at least four times in synapsids during the Late Carboniferous and Early Permian. Furthermore, similarities in the morphologies of the sacral vertebrae and ribs of these early synapsids lead us to conclude that an anterior caudal vertebra had been incorporated into the sacral series convergently in these groups. Given the repeated acquisition of a three-vertebra sacrum in early synapsids and no apparent link to body size, we argue that this sacral anatomy was related to more efficient terrestrial locomotion than to increased weight bearing.
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Affiliation(s)
- Aaron R. H. LeBlanc
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
- * E-mail:
| | - Robert R. Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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