1
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Drumheller SK, Boyd CA, Barnes BMS, Householder ML. Biostratinomic alterations of an Edmontosaurus "mummy" reveal a pathway for soft tissue preservation without invoking "exceptional conditions". PLoS One 2022; 17:e0275240. [PMID: 36223345 PMCID: PMC9555629 DOI: 10.1371/journal.pone.0275240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/12/2022] [Indexed: 11/05/2022] Open
Abstract
Removal or protection from biostratinomic agents of decomposition, such as predators and scavengers, is widely seen as a requirement for high-quality preservation of soft tissues in the fossil record. In this context, extremely rapid burial is an oft-cited mechanism for shielding remains from degradation, but not all fossils fit nicely into this paradigm. Dinosaurian mummies in particular seemingly require two mutually exclusive taphonomic processes to preserve under that framework: desiccation and rapid burial. Here we present a recently prepared Edmontosaurus mummy that reveals an alternate fossilization pathway for resistant soft tissues (e.g., skin and nails). While the skin on this specimen is well-preserved in three dimensions and contains biomarkers, it is deflated and marked by the first documented examples of injuries consistent with carnivore activity on dinosaurian soft tissue during the perimortem interval. Incomplete scavenging of the carcass provided a route for the gases, fluids, and microbes associated with decomposition to escape, allowing more durable soft tissues to persist through the weeks to months required for desiccation prior to entombment and fossilization. This pathway is consistent with actualistic observations and explains why dinosaurian skin, while rare, is more commonly preserved than expected if extreme circumstances were required for its preservation. More broadly, our assumptions guide specimen collection and research, and the presence of soft tissues and biomolecules in fossils that demonstrably were not rapidly buried, such as this mummy, suggests that such types of evidence may be substantially more common than previously assumed.
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Affiliation(s)
- Stephanie K. Drumheller
- Department of Earth and Planetary Sciences, University of Tennessee–Knoxville, Knoxville, Tennessee, United States of America
- * E-mail: (SKD); (CAB)
| | - Clint A. Boyd
- Fossil Resource Management Program, North Dakota Geological Survey, Bismarck, North Dakota, United States of America
- * E-mail: (SKD); (CAB)
| | - Becky M. S. Barnes
- Fossil Resource Management Program, North Dakota Geological Survey, Bismarck, North Dakota, United States of America
| | - Mindy L. Householder
- State Historical Society of North Dakota, Bismarck, North Dakota, United States of America
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2
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Hartung J, Böhme M. Unexpected cranial sexual dimorphism in the tragulid Dorcatherium naui based on material from the middle to late Miocene localities of Eppelsheim and Hammerschmiede (Germany). PLoS One 2022; 17:e0267951. [PMID: 35584185 PMCID: PMC9116667 DOI: 10.1371/journal.pone.0267951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 04/19/2022] [Indexed: 11/19/2022] Open
Abstract
Tragulids, chevrotains or mouse deer, were common faunal elements during the Miocene. During that time, Dorcatherium was the most abundant genus, with D. naui being the first described species. Besides their abundance, until recently only very limited cranial material was available for investigation. Here we present a redescription of the first complete skull of D. naui from the middle to late Miocene locality of Eppelsheim, Germany, based on micro-computed tomography. Furthermore, we present a description and comparison of two additional, new skulls of D. naui from the late Miocene hominid locality Hammerschmiede, Germany. Within Dorcatherium, so far, only three other complete skulls are known, all belonging to D. crassum. A comparison between the three skulls of D. naui and the already known skulls of D. crassum shows that these two species differ in morphological features of the skull, such as laterally facing orbitae, separation of supraorbital foramen from supraorbital groove by a bony bridge, well-developed parietal plateau, prominent nuchal tubercle, less-developed nuchal crests, and the presence of an occipital crest. Moreover, two different osteological morphotypes are present in the skulls of D. naui that can be interpreted as a previously unknown sexual dimorphism. Very similar features are observed in D. crassum, which can be likewise related to the same dimorphism. However, males of D. naui differ from males of D. crassum by the presence of frontoparietal bulges, which were probably used for sexual display and during male-male combats in males of D. naui. For the first time, sexual dimorphism in Dorcatherium is described based on skull characteristics, which are, so far, unknown from any other fossil or extant tragulid.
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Affiliation(s)
- Josephina Hartung
- Department of Geosciences, Eberhard Karls University, Tübingen, Germany
- * E-mail:
| | - Madelaine Böhme
- Department of Geosciences, Eberhard Karls University, Tübingen, Germany
- Senckenberg Centre for Human Evolution and Paleoenvironment (HEP), Tübingen, Germany
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3
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Enriquez NJ, Campione NE, White MA, Fanti F, Sissons RL, Sullivan C, Vavrek MJ, Bell PR. The dinosaur tracks of Tyrants Aisle: An Upper Cretaceous ichnofauna from Unit 4 of the Wapiti Formation (upper Campanian), Alberta, Canada. PLoS One 2022; 17:e0262824. [PMID: 35108301 PMCID: PMC8809565 DOI: 10.1371/journal.pone.0262824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 01/05/2022] [Indexed: 11/19/2022] Open
Abstract
The Wapiti Formation of northwest Alberta and northeast British Columbia, Canada, preserves an Upper Cretaceous terrestrial vertebrate fauna that is latitudinally situated between those documented further north in Alaska and those from southern Alberta and the contiguous U.S.A. Therefore, the Wapiti Formation is important for identifying broad patterns in vertebrate ecology, diversity, and distribution across Laramidia during the latest Cretaceous. Tracksites are especially useful as they provide a range of palaeoecological, palaeoenvironmental, and behavioural data that are complementary to the skeletal record. Here, we describe the Tyrants Aisle locality, the largest in-situ tracksite known from the Wapiti Formation. The site occurs in the lower part of Unit 4 of the formation (~72.5 Ma, upper Campanian), exposed along the southern bank of the Redwillow River. More than 100 tracks are documented across at least three distinct track-bearing layers, which were deposited on an alluvial floodplain. Hadrosaurid tracks are most abundant, and are referable to Hadrosauropodus based on track width exceeding track length, broad digits, and rounded or bilobed heel margins. We suggest the hadrosaurid trackmaker was Edmontosaurus regalis based on stratigraphic context. Tyrannosaurids, probable troodontids, possible ornithomimids, and possible azhdarchid pterosaurs represent minor but notable elements of the ichnofauna, as the latter is unknown from skeletal remains within the Wapiti Formation, and all others are poorly represented. Possible social behaviour is inferred for some of the hadrosaurid and small theropod-like trackmakers based on trackway alignment, suitable spacing and consistent preservation. On a broad taxonomic level (i.e., family or above), ichnofaunal compositions indicate that hadrosaurids were palaeoecologically dominant across Laramidia during the late Campanian within both high-and low-latitude deposits, although the role of depositional environment requires further testing.
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Affiliation(s)
- Nathan J. Enriquez
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Nicolás E. Campione
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Matt A. White
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Federico Fanti
- Dipartimento di Scienze della Terra e Geologico-Ambientali, Alma Mater Studiorum, Università di Bologna, Bologna, Italy
| | - Robin L. Sissons
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Corwin Sullivan
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Philip J. Currie Dinosaur Museum, Wembley, Alberta, Canada
| | - Matthew J. Vavrek
- Cutbank Palaeontological Consulting, Grande Prairie, Alberta, Canada
- Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
| | - Phil R. Bell
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
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4
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Hendrickx C, Bell PR, Pittman M, Milner ARC, Cuesta E, O'Connor J, Loewen M, Currie PJ, Mateus O, Kaye TG, Delcourt R. Morphology and distribution of scales, dermal ossifications, and other non-feather integumentary structures in non-avialan theropod dinosaurs. Biol Rev Camb Philos Soc 2022; 97:960-1004. [PMID: 34991180 DOI: 10.1111/brv.12829] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/10/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022]
Abstract
Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non-feathered integumentary structures in non-avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non-averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non-scale bearing skin is found in the contentious tetanuran Sciurumimus, ornithomimosaurians (Ornithomimus) and possibly tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non-avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake-like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co-occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.
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Affiliation(s)
- Christophe Hendrickx
- Unidad Ejecutora Lillo, CONICET-Fundación Miguel Lillo, 251 Miguel Lillo, San Miguel de Tucumán, Tucumán, 4000, Argentina
| | - Phil R Bell
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Michael Pittman
- Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China.,Department of Earth Sciences, University College London, WC1E 6BT, United Kingdom
| | - Andrew R C Milner
- St. George Dinosaur Discovery Site at Johnson Farm, 2180 East Riverside Drive, St. George, UT, U.S.A
| | - Elena Cuesta
- Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, Munich, 80333, Germany
| | - Jingmai O'Connor
- Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL, 60605, U.S.A
| | - Mark Loewen
- Department of Geology and Geophysics, University of Utah, Frederick Albert Sutton Building, 115 South 1460 East, Salt Lake City, UT, 84112, U.S.A.,Natural History Museum of Utah, 301 Wakara Way, Salt Lake City, UT, 84108, U.S.A
| | - Philip J Currie
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Octávio Mateus
- GeoBioTec, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.,Museu da Lourinhã, 95 Rua João Luis de Moura, Lourinhã, 2530-158, Portugal
| | - Thomas G Kaye
- Foundation for Scientific Advancement, 7023 Alhambra Dr., Sierra Vista, AZ, 85650, U.S.A
| | - Rafael Delcourt
- Universidade Estadual de Campinas (UNICAMP), Instituto de Geociências, Cidade Universitária, Rua Carlos Gomes, 250, Campinas, SP, 13083-855, Brazil
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5
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Whitebone SA, Bari ASMH, Gavrilova ML, Anderson JS. A multimethod approach to the differentiation of enthesis bone microstructure based on soft tissue type. J Morphol 2021; 282:1362-1373. [PMID: 34181767 DOI: 10.1002/jmor.21391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 05/26/2021] [Accepted: 06/25/2021] [Indexed: 12/20/2022]
Abstract
Whereas there is a wealth of research studying the nature of various soft tissues that attach to bone, comparatively little research focuses on the bone's microscopic properties in the area where these tissues attach. Using scanning electron microscopy to generate a dataset of 1600 images of soft tissue attachment sites, an image classification program with novel convolutional neural network architecture can categorize images of attachment areas by soft tissue type based on observed patterns in microstructure morphology. Using stained histological thin section and liquid crystal cross-polarized microscopy, it is determined that soft tissue type can be quantitatively determined from the microstructure. The primary diagnostic characters are the orientation of collagen fibers and heterogeneity of collagen density throughout the attachment area thickness. These determinations are made across broad taxonomic sampling and multiple skeletal elements.
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Affiliation(s)
- S Amber Whitebone
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - A S M Hossain Bari
- Departments of Computer Science, University of Calgary, Calgary, Alberta, Canada
| | - Marina L Gavrilova
- Departments of Computer Science, University of Calgary, Calgary, Alberta, Canada
| | - Jason S Anderson
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
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6
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Holland B, Bell PR, Fanti F, Hamilton SM, Larson DW, Sissons R, Sullivan C, Vavrek MJ, Wang Y, Campione NE. Taphonomy and taxonomy of a juvenile lambeosaurine (Ornithischia: Hadrosauridae) bonebed from the late Campanian Wapiti Formation of northwestern Alberta, Canada. PeerJ 2021; 9:e11290. [PMID: 33987001 PMCID: PMC8103918 DOI: 10.7717/peerj.11290] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/26/2021] [Indexed: 01/26/2023] Open
Abstract
Hadrosaurid (duck-billed) dinosaur bonebeds are exceedingly prevalent in upper Cretaceous (Campanian–Maastrichtian) strata from the Midwest of North America (especially Alberta, Canada, and Montana, U.S.A) but are less frequently documented from more northern regions. The Wapiti Formation (Campanian–Maastrichtian) of northwestern Alberta is a largely untapped resource of terrestrial palaeontological information missing from southern Alberta due to the deposition of the marine Bearpaw Formation. In 2018, the Boreal Alberta Dinosaur Project rediscovered the Spring Creek Bonebed, which had been lost since 2002, along the northern bank of the Wapiti River, southwest of Grande Prairie. Earlier excavations and observations of the Spring Creek Bonebed suggested that the site yielded young hadrosaurines. Continued work in 2018 and 2019 recovered ~300 specimens that included a minimum of eight individuals, based on the number of right humeri. The morphology of several recovered cranial elements unequivocally supports lambeosaurine affinities, making the Spring Creek sample the first documented occurrence of lambeosaurines in the Wapiti Formation. The overall size range and histology of the bones found at the site indicate that these animals were uniformly late juveniles, suggesting that age segregation was a life history strategy among hadrosaurids. Given the considerable size attained by the Spring Creek lambeosaurines, they were probably segregated from the breeding population during nesting or caring for young, rather than due to different diet and locomotory requirements. Dynamic aspects of life history, such as age segregation, may well have contributed to the highly diverse and cosmopolitan nature of Late Cretaceous hadrosaurids.
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Affiliation(s)
- Brayden Holland
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
| | - Phil R Bell
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
| | - Federico Fanti
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, Università di Bologna, Bologna, Italy
| | - Samantha M Hamilton
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Derek W Larson
- Philip J. Currie Dinosaur Museum, Wembley, Alberta, Canada
| | - Robin Sissons
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Corwin Sullivan
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Philip J. Currie Dinosaur Museum, Wembley, Alberta, Canada
| | - Matthew J Vavrek
- Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
| | - Yanyin Wang
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Nicolás E Campione
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
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7
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Kobayashi Y, Takasaki R, Kubota K, Fiorillo AR. A new basal hadrosaurid (Dinosauria: Ornithischia) from the latest Cretaceous Kita-ama Formation in Japan implies the origin of hadrosaurids. Sci Rep 2021; 11:8547. [PMID: 33903622 PMCID: PMC8076177 DOI: 10.1038/s41598-021-87719-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/01/2021] [Indexed: 11/21/2022] Open
Abstract
Here we describe a partial hadrosaurid skeleton from the marine Maastrichtian Kita-ama Formation in Japan as a new taxon, Yamatosaurus izanagii gen. et sp. nov., based on unique characters in the dentition. Our phylogenetic analysis demonstrates Yamatosaurus izanagii belongs to Hadrosauridae, composed of Hadrosaurus foulkii + (Yamatosaurus izanagii + (Saurolophinae + Lambeosaurinae)). The coracoid lacks a biceps tubercle as in non-hadrosaurid hadrosauroids, suggesting its presence is a key feature for the clade of Saurolophinae and Lambeosaurinae. The evolutionary rates analysis further supports that shoulder and forelimb features, which are likely to have been involved in locomotion, were important for the early evolution of Hadrosauridae. Our biogeographic analyses show that basal hadrosaurids were widely distributed in Asia and Appalachia, that the clade of Saurolophinae and Lambeosaurinae originated in Asia, and that eastern Asia may have served as a refugium of relict hadrosauroid taxa such as Plesiohadros djadokhtaensis, Tanius sinensis, and Yamatosaurus izanagii during the Late Cretaceous. The contemporaneous occurrence of basal (Yamatosaurus izanagii) and derived (Kamuysaurus japonicus) hadrosaurids during the Maastrichtian in Japan is the first record in Asia. Because of the long geographical distance between these localities, they likely did not co-exist, but instead demonstrate some level of provinciality.
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Affiliation(s)
- Yoshitsugu Kobayashi
- Hokkaido University Museum, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
| | - Ryuji Takasaki
- Faculty of Biosphere-Geosphere Science, Okayama University of Science, Okayama, 700-0005, Japan
| | - Katsuhiro Kubota
- Hokkaido University Museum, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
- Museum of Nature and Human Activities, Hyogo, Sanda, Hyogo, 669-1546, Japan
- Institute of Natural and Environmental Sciences, University of Hyogo, Sanda, Hyogo, 669-1546, Japan
| | - Anthony R Fiorillo
- Hokkaido University Museum, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
- Institute for the Study of Earth and Man, Southern Methodist University, Dallas, TX, 75275, USA
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8
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Griffin CT, Stocker MR, Colleary C, Stefanic CM, Lessner EJ, Riegler M, Formoso K, Koeller K, Nesbitt SJ. Assessing ontogenetic maturity in extinct saurian reptiles. Biol Rev Camb Philos Soc 2020; 96:470-525. [PMID: 33289322 DOI: 10.1111/brv.12666] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life-history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least-inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260-million-year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and cross-study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method-specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well-represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well-constrained, empirically tested methods.
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Affiliation(s)
- Christopher T Griffin
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Michelle R Stocker
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Caitlin Colleary
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH, 44106, U.S.A
| | - Candice M Stefanic
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Anatomical Sciences, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, U.S.A
| | - Emily J Lessner
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Pathology and Anatomical Sciences, University of Missouri, 1 Hospital Drive, Columbia, MO, 65212, U.S.A
| | - Mitchell Riegler
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL, 32611, U.S.A
| | - Kiersten Formoso
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA, 90089, U.S.A
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA, 90007, U.S.A
| | - Krista Koeller
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611, U.S.A
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
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9
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Bertozzo F, Manucci F, Dempsey M, Tanke DH, Evans DC, Ruffell A, Murphy E. Description and etiology of paleopathological lesions in the type specimen of Parasaurolophus walkeri (Dinosauria: Hadrosauridae), with proposed reconstructions of the nuchal ligament. J Anat 2020; 238:1055-1069. [PMID: 33289113 PMCID: PMC8053592 DOI: 10.1111/joa.13363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/23/2020] [Accepted: 10/30/2020] [Indexed: 01/08/2023] Open
Abstract
Paleopathology, or the study of ancient injuries and diseases, can enable the ecology and life history of extinct taxa to be deciphered. Large-bodied ornithopods are the dinosaurs with the highest frequencies of paleopathology reported to-date. Among these, the crested hadrosaurid Parasaurolophus walkeri is one of the most famous, largely due to its dramatic elongated and tubular nasal crest. The holotype of Parasaurolophus walkeri at the Royal Ontario Museum, Canada, displays several paleopathologies that have not been discussed in detail previously: a dental lesion in the left maxilla, perhaps related to periodontal disease; callus formation associated with fractures in three dorsal ribs; a discoidal overgrowth above dorsal neural spines six and seven; a cranially oriented spine in dorsal seven, that merges distally with spine six; a V-shaped gap between dorsal spines seven and eight; and a ventral projection of the pubic process of the ilium which covers, and is fused with, the lateral side of the iliac process of the pubis. These lesions suggest that the animal suffered from one or more traumatic events, with the main one causing a suite of injuries to the anterior aspect of the thorax. The presence of several lesions in a single individual is a rare observation and, in comparison with a substantial database of hadrosaur paleopathological lesions, has the potential to reveal new information about the biology and behavior of these ornithopods. The precise etiology of the iliac abnormality is still unclear, although it is thought to have been an indirect consequence of the anterior trauma. The discoidal overgrowth above the two neural spines also seems to be secondary to the severe trauma inflicted on the ribs and dorsal spines, and probably represents post-traumatic ossification of the base of the nuchal ligament. The existence of this structure has previously been considered in hadrosaurs and dinosaurs more generally through comparison of origin and insertion sites in modern diapsids (Rhea americana, Alligator mississippiensis, Iguana iguana), but its presence, structure, and origin-attachment sites are still debated. The V-shaped gap is hypothesized as representing the point between the stresses of the nuchal ligament, pulling the anterior neural spines forward, and the ossified tendons pulling the posterior neural spines backward. Different reconstructions of the morphology of the structure based on the pathological conditions affecting the neural spines of ROM 768 are proposed. Finally, we review the history of reconstructions for Parasaurolophus walkeri showing how erroneous misconceptions have been perpetuated over time or have led to the development of new hypotheses, including the wide neck model supported in the current research.
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Affiliation(s)
- Filippo Bertozzo
- School of Natural and Built EnvironmentQueen’s University BelfastBelfastUK
- CI2PaleoSociedade de Historia NaturalTorres VedrasPortugal
| | - Fabio Manucci
- Associazione Paleontologica Paleoartistica ItalianaParmaItaly
| | - Matthew Dempsey
- Department of Musculoskeletal & Ageing ScienceUniversity of LiverpoolLiverpoolUK
| | | | - David C. Evans
- Royal Ontario MuseumTorontoONCanada
- Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Alastair Ruffell
- School of Natural and Built EnvironmentQueen’s University BelfastBelfastUK
| | - Eileen Murphy
- School of Natural and Built EnvironmentQueen’s University BelfastBelfastUK
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10
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Saitta ET, Stockdale MT, Longrich NR, Bonhomme V, Benton MJ, Cuthill IC, Makovicky PJ. An effect size statistical framework for investigating sexual dimorphism in non-avian dinosaurs and other extinct taxa. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Abstract
Despite reports of sexual dimorphism in extinct taxa, such claims in non-avian dinosaurs have been rare over the last decade and have often been criticized. Since dimorphism is widespread in sexually reproducing organisms today, under-reporting in the literature might suggest either methodological shortcomings or that this diverse group exhibited highly unusual reproductive biology. Univariate significance testing, especially for bimodality, is ineffective and prone to false negatives. Species recognition and mutual sexual selection hypotheses, therefore, may not be required to explain supposed absence of sexual dimorphism across the grade (a type II error). Instead, multiple lines of evidence support sexual selection and variation of structures consistent with secondary sexual characteristics, strongly suggesting sexual dimorphism in non-avian dinosaurs. We propose a framework for studying sexual dimorphism in fossils, focusing on likely secondary sexual traits and testing against all alternate hypotheses for variation in them using multiple lines of evidence. We use effect size statistics appropriate for low sample sizes, rather than significance testing, to analyse potential divergence of growth curves in traits and constrain estimates for dimorphism magnitude. In many cases, estimates of sexual variation can be reasonably accurate, and further developments in methods to improve sex assignments and account for intrasexual variation (e.g. mixture modelling) will improve accuracy. It is better to compare estimates for the magnitude of and support for dimorphism between datasets than to dichotomously reject or fail to reject monomorphism in a single species, enabling the study of sexual selection across phylogenies and time. We defend our approach with simulated and empirical data, including dinosaur data, showing that even simple approaches can yield fairly accurate estimates of sexual variation in many cases, allowing for comparison of species with high and low support for sexual variation.
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Affiliation(s)
- Evan T Saitta
- Life Sciences Section, Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA
| | | | - Nicholas R Longrich
- Department of Biology and Biochemistry and Milner Centre for Evolution, University of Bath, Bath, UK
| | - Vincent Bonhomme
- Institut des sciences de l’évolution, Université de Montpellier, Montpellier, France
| | | | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Peter J Makovicky
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA
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11
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Barbi M, Bell PR, Fanti F, Dynes JJ, Kolaceke A, Buttigieg J, Coulson IM, Currie PJ. Integumentary structure and composition in an exceptionally well-preserved hadrosaur (Dinosauria: Ornithischia). PeerJ 2019; 7:e7875. [PMID: 31637130 PMCID: PMC6800526 DOI: 10.7717/peerj.7875] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 09/11/2019] [Indexed: 12/19/2022] Open
Abstract
Preserved labile tissues (e.g., skin, muscle) in the fossil record of terrestrial vertebrates are increasingly becoming recognized as an important source of biological and taphonomic information. Here, we combine a variety of synchrotron radiation techniques with scanning electron and optical microscopy to elucidate the structure of 72 million-year-old squamous (scaly) skin from a hadrosaurid dinosaur from the Late Cretaceous of Alberta, Canada. Scanning electron and optical microscopy independently reveal that the three-dimensionally preserved scales are associated with a band of carbon-rich layers up to a total thickness of ∼75 microns, which is topographically and morphologically congruent with the stratum corneum in modern reptiles. Compositionally, this band deviates from that of the surrounding sedimentary matrix; Fourier-transform infrared spectroscopy and soft X-ray spectromicroscopy analyses indicate that carbon appears predominantly as carbonyl in the skin. The regions corresponding to the integumentary layers are distinctively enriched in iron compared to the sedimentary matrix and appear with kaolinite-rich laminae. These hosting carbonyl-rich layers are apparently composed of subcircular bodies resembling preserved cell structures. Each of these structures is encapsulated by calcite/vaterite, with iron predominantly concentrated at its center. The presence of iron, calcite/vaterite and kaolinite may, independently or collectively, have played important roles in the preservation of the layered structures.
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Affiliation(s)
- Mauricio Barbi
- Department of Physics, University of Regina, Regina, Saskatchewan, Canada
| | - Phil R Bell
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
| | - Federico Fanti
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, Università di Bologna, Bologna, Italy.,Museo Geologico Giovanni Capellini, Università di Bologna, Bologna, Italy
| | - James J Dynes
- Canadian Light Source Inc., University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Anezka Kolaceke
- Department of Physics, University of Regina, Regina, Saskatchewan, Canada
| | - Josef Buttigieg
- Department of Biology, University of Regina, Regina, Saskatchewan, Canada
| | - Ian M Coulson
- Department of Geology, University of Regina, Regina, Saskatchewan, Canada
| | - Philip J Currie
- Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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12
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Kobayashi Y, Nishimura T, Takasaki R, Chiba K, Fiorillo AR, Tanaka K, Chinzorig T, Sato T, Sakurai K. A New Hadrosaurine (Dinosauria: Hadrosauridae) from the Marine Deposits of the Late Cretaceous Hakobuchi Formation, Yezo Group, Japan. Sci Rep 2019; 9:12389. [PMID: 31488887 PMCID: PMC6728324 DOI: 10.1038/s41598-019-48607-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 08/02/2019] [Indexed: 11/10/2022] Open
Abstract
A nearly complete skeleton of a new hadrosaurid, Kamuysaurus japonicus gen. et sp. nov., was discovered from the outer shelf deposits of the Upper Cretaceous Hakobuchi Formation of the Yezo Group in Hobetsu area of Mukawa town in Hokkaido, Japan. Kamuysaurus belongs to the sub-clade of Hadrosaurinae, Edmontosaurini, and forms a monophyly with Laiyangosaurus and Kerberosaurus from the northern Far East. Kamuysaurus has a long anterior platform for the nasofrontal sutural surface, which may indicate the presence of a small supracranial crest, similar to a sub-adult form of Brachylophosaurus based on the extension of the nasofrontal sutural surface. The Dispersal Extinction Cladogenesis analysis with the 50% Majority Rule consensus tree suggests that the clade of Kamuysaurus, Laiyangosaurus, and Kerberosaurus may have dispersed into Asia prior to the late Campanian and the potential endemism of this clade during the late Campanian and early Maastrichtian in the northern Far East. The results of both Dispersal Extinction Cladogenesis and Ancestral State Reconstruction analyses imply that the marine-influenced environment in North America during the Campanian may have played an important role for the hadrosaurid diversification in its early evolutionary history.
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Affiliation(s)
- Yoshitsugu Kobayashi
- Hokkaido University Museum, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
| | | | - Ryuji Takasaki
- Department of Natural History and Planetary Sciences, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
| | - Kentaro Chiba
- Faculty of Biosphere-Geosphere Science, Okayama University of Science, Okayama, 700-0005, Japan
| | | | - Kohei Tanaka
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Tsogtbaatar Chinzorig
- Division of Vertebrate Paleontology, Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, 15160, Mongolia
| | - Tamaki Sato
- Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo, 184-8501, Japan
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13
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Abstract
This Outlook discusses Beytebiere et al.’s finding that the ability of BMAL1 to drive tissue-specific rhythmic transcription is associated with not only the activity of BMAL1-bound enhancers but also the activity of neighboring enhancers. The circadian clock in the suprachiasmatic nucleus (SCN) of mammals drives 24-h rhythms of sleep/wake cycles. Peripheral clocks present in other organs coordinate local and global physiology according to rhythmic signals from the SCN and via metabolic cues. The core circadian clockwork is identical in all cells. However, there is only a small amount of overlap of the circadian transcriptomes in different organs and tissues. A novel study by Beytebiere and colleagues (pp. 294–309) indicates that the regulation of tissue-specific rhythmic gene expression involves the cooperation of the circadian transcription factor (TF) BMAL1:CLOCK with tissue-specific TFs (ts-TFs) and correlates with the potential of BMAL1:CLOCK to facilitate rhythmic enhancer–enhancer interactions.
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Affiliation(s)
- Anton Shostak
- Heidelberg University Biochemistry Center, Heidelberg D-69120, Germany
| | - Michael Brunner
- Heidelberg University Biochemistry Center, Heidelberg D-69120, Germany
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14
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Beytebiere JR, Trott AJ, Greenwell BJ, Osborne CA, Vitet H, Spence J, Yoo SH, Chen Z, Takahashi JS, Ghaffari N, Menet JS. Tissue-specific BMAL1 cistromes reveal that rhythmic transcription is associated with rhythmic enhancer-enhancer interactions. Genes Dev 2019; 33:294-309. [PMID: 30804225 PMCID: PMC6411008 DOI: 10.1101/gad.322198.118] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 01/02/2019] [Indexed: 12/31/2022]
Abstract
The mammalian circadian clock relies on the transcription factor CLOCK:BMAL1 to coordinate the rhythmic expression of thousands of genes. Consistent with the various biological functions under clock control, rhythmic gene expression is tissue-specific despite an identical clockwork mechanism in every cell. Here we show that BMAL1 DNA binding is largely tissue-specific, likely because of differences in chromatin accessibility between tissues and cobinding of tissue-specific transcription factors. Our results also indicate that BMAL1 ability to drive tissue-specific rhythmic transcription is associated with not only the activity of BMAL1-bound enhancers but also the activity of neighboring enhancers. Characterization of physical interactions between BMAL1 enhancers and other cis-regulatory regions by RNA polymerase II chromatin interaction analysis by paired-end tag (ChIA-PET) reveals that rhythmic BMAL1 target gene expression correlates with rhythmic chromatin interactions. These data thus support that much of BMAL1 target gene transcription depends on BMAL1 capacity to rhythmically regulate a network of enhancers.
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Affiliation(s)
- Joshua R Beytebiere
- Department of Biology, Center for Biological Clocks Research, Texas A&M University, College Station, Texas 77843, USA
| | - Alexandra J Trott
- Department of Biology, Center for Biological Clocks Research, Texas A&M University, College Station, Texas 77843, USA
- Program of Genetics, Texas A&M University, College Station, Texas 77843, USA
| | - Ben J Greenwell
- Department of Biology, Center for Biological Clocks Research, Texas A&M University, College Station, Texas 77843, USA
- Program of Genetics, Texas A&M University, College Station, Texas 77843, USA
| | - Collin A Osborne
- Department of Biology, Center for Biological Clocks Research, Texas A&M University, College Station, Texas 77843, USA
- Program of Genetics, Texas A&M University, College Station, Texas 77843, USA
| | - Helene Vitet
- Department of Biology, Center for Biological Clocks Research, Texas A&M University, College Station, Texas 77843, USA
| | - Jessica Spence
- Department of Biology, Center for Biological Clocks Research, Texas A&M University, College Station, Texas 77843, USA
| | - Seung-Hee Yoo
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Zheng Chen
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Joseph S Takahashi
- Department of Neuroscience, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Noushin Ghaffari
- Center for Bioinformatics and Genomic Systems Engineering (CBGSE), Texas A&M AgriLife Research, College Station, Texas 77845, USA
- AgriLife Genomics and Bioinformatics, Texas A&M AgriLife Research, College Station, Texas 77845, USA
| | - Jerome S Menet
- Department of Biology, Center for Biological Clocks Research, Texas A&M University, College Station, Texas 77843, USA
- Program of Genetics, Texas A&M University, College Station, Texas 77843, USA
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15
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Top D, Young MW. Coordination between Differentially Regulated Circadian Clocks Generates Rhythmic Behavior. Cold Spring Harb Perspect Biol 2018; 10:a033589. [PMID: 28893860 PMCID: PMC6028074 DOI: 10.1101/cshperspect.a033589] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Specialized groups of neurons in the brain are key mediators of circadian rhythms, receiving daily environmental cues and communicating those signals to other tissues in the organism for entrainment and to organize circadian physiology. In Drosophila, the "circadian clock" is housed in seven neuronal clusters, which are defined by their expression of the main circadian proteins, Period, Timeless, Clock, and Cycle. These clusters are distributed across the fly brain and are thereby subject to the respective environments associated with their anatomical locations. While these core components are universally expressed in all neurons of the circadian network, additional regulatory proteins that act on these components are differentially expressed, giving rise to "local clocks" within the network that nonetheless converge to regulate coherent behavioral rhythms. In this review, we describe the communication between the neurons of the circadian network and the molecular differences within neurons of this network. We focus on differences in protein-expression patterns and discuss how such variation can impart functional differences in each local clock. Finally, we summarize our current understanding of how communication within the circadian network intersects with intracellular biochemical mechanisms to ultimately specify behavioral rhythms. We propose that additional efforts are required to identify regulatory mechanisms within each neuronal cluster to understand the molecular basis of circadian behavior.
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Affiliation(s)
- Deniz Top
- Laboratory of Genetics, The Rockefeller University, New York, New York 10065
| | - Michael W Young
- Laboratory of Genetics, The Rockefeller University, New York, New York 10065
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16
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Zizzari ZV, Jessen A, Koene JM. Male reproductive suppression: not a social affair. Curr Zool 2018; 63:573-579. [PMID: 29492017 PMCID: PMC5804194 DOI: 10.1093/cz/zow089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/27/2016] [Indexed: 12/16/2022] Open
Abstract
In the animal kingdom there are countless strategies via which males optimize their reproductive success when faced with male–male competition. These male strategies typically fall into two main categories: pre- and post-copulatory competition. Within these 2 categories, a set of behaviors, referred to as reproductive suppression, is known to cause inhibition of reproductive physiology and/or reproductive behavior in an otherwise fertile individual. What becomes evident when considering examples of reproductive suppression is that these strategies conventionally encompass reproductive interference strategies that occur between members of a hierarchical social group. However, mechanisms aimed at impairing a competitor’s reproductive output are also present in non-social animals. Yet, current thinking emphasizes the importance of sociality as the primary driving force of reproductive suppression. Therefore, the question arises as to whether there is an actual difference between reproductive suppression strategies in social animals and equivalent pre-copulatory competition strategies in non-social animals. In this perspective paper we explore a broad taxonomic range of species whose individuals do not repeatedly interact with the same individuals in networks and yet, depress the fitness of rivals. Examples like alteration of male reproductive physiology, female mimicry, rival spermatophore destruction, and cementing the rival’s genital region in non-social animals, highlight that male pre-copulatory reproductive suppression and male pre-copulatory competition overlap. Finally, we highlight that a distinction between male reproductive interference in animals with and without a social hierarchy might obscure important similarities and does not help to elucidate why different proximate mechanisms evolved. We therefore emphasize that male reproductive suppression need not be restricted to social animals.
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Affiliation(s)
- Z Valentina Zizzari
- Department of Ecological Science-Animal Ecology, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Andrea Jessen
- Department of Ecological Science-Animal Ecology, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Joris M Koene
- Department of Ecological Science-Animal Ecology, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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17
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Brown CM. An exceptionally preserved armored dinosaur reveals the morphology and allometry of osteoderms and their horny epidermal coverings. PeerJ 2017; 5:e4066. [PMID: 29201564 PMCID: PMC5712211 DOI: 10.7717/peerj.4066] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 10/29/2017] [Indexed: 12/04/2022] Open
Abstract
Although the evolution and function of "exaggerated" bony projections in ornithischian dinosaurs has been subject to significant debate recently, our understanding of the structure and morphology of their epidermal keratinized coverings is greatly limited. The holotype of Borealopelta, a new nodosaurid ankylosaur, preserves osteoderms and extensive epidermal structures (dark organic residues), in anatomic position across the entire precaudal length. Contrasting previous specimens, organic epiosteodermal scales, often in the form of horn-like (keratinous) sheaths, cap and exaggerate nearly all osteoderms, allowing for morphometric and allometric analyses of both the bony osteoderms and their horny sheaths. A total of 172 osteoderms were quantified, with osteoderm spine length and height being positively allometric with respect to basal length and width. Despite tight correlations between the different measures amongst all other osteoderms, the large parascapular spines represent consistent outliers. Thickness and relative contribution of the keratinized epiosteodermal scales/sheaths varies greatly by region, ranging from 2% to 6% for posterior thoracics, to ∼25% (1.3×) for the parascapular spines-similar to horn sheaths in some bovid analogues. Relative to the bony cores, the horny portions of the spines are strongly positively allometric (slope = 2.3, CI = 1.8-2.8). Strong allometric scaling, species-specific morphology, and significant keratinous extension of the cervicoscapular spines is consistent with elaboration under socio-sexual selection. This marks the first allometric analysis of ornithischian soft tissues.
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Affiliation(s)
- Caleb M. Brown
- Royal Tyrrell Museum of Palaeontology, Drumheller, AB, Canada
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18
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Bachir AI, Horwitz AR, Nelson WJ, Bianchini JM. Actin-Based Adhesion Modules Mediate Cell Interactions with the Extracellular Matrix and Neighboring Cells. Cold Spring Harb Perspect Biol 2017; 9:9/7/a023234. [PMID: 28679638 DOI: 10.1101/cshperspect.a023234] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cell adhesions link cells to the extracellular matrix (ECM) and to each other and depend on interactions with the actin cytoskeleton. Both cell-ECM and cell-cell adhesion sites contain discrete, yet overlapping, functional modules. These modules establish physical associations with the actin cytoskeleton, locally modulate actin organization and dynamics, and trigger intracellular signaling pathways. Interplay between these modules generates distinct actin architectures that underlie different stages, types, and functions of cell-ECM and cell-cell adhesions. Actomyosin contractility is required to generate mature, stable adhesions, as well as to sense and translate the mechanical properties of the cellular environment into changes in cell organization and behavior. Here, we review the organization and function of different adhesion modules and how they interact with the actin cytoskeleton. We highlight the molecular mechanisms of mechanotransduction in adhesions and how adhesion molecules mediate cross talk between cell-ECM and cell-cell adhesion sites.
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Affiliation(s)
- Alexia I Bachir
- Protein and Cell Analysis, Biosciences Division, Thermo Fisher Scientific, Eugene, Oregon 97402
| | - Alan Rick Horwitz
- Protein and Cell Analysis, Biosciences Division, Thermo Fisher Scientific, Eugene, Oregon 97402
| | - W James Nelson
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22903
| | - Julie M Bianchini
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22903
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19
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Xing H, Mallon JC, Currie ML. Supplementary cranial description of the types of Edmontosaurus regalis (Ornithischia: Hadrosauridae), with comments on the phylogenetics and biogeography of Hadrosaurinae. PLoS One 2017; 12:e0175253. [PMID: 28384240 PMCID: PMC5383305 DOI: 10.1371/journal.pone.0175253] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 03/22/2017] [Indexed: 11/18/2022] Open
Abstract
The cranial anatomy of the flat-skulled hadrosaurine Edmontosaurus regalis (Ornithischia: Hadrosauridae) is extensively described here, based on the holotype and paratype collected from the middle part of the Horseshoe Canyon Formation in southern Alberta. Focus is given to previously undocumented features of ontogenetic and phylogenetic importance. This description facilitates overall osteological comparisons between E. regalis and other hadrosaurids (especially E. annectens), and revises the diagnosis of E. regalis, to which a new autapomorphy (the dorsal half of the jugal anterior process bearing a sharp posterolateral projection into the orbit) is added. We consider the recently named Ugrunaaluk kuukpikensis from the upper Campanian/lower Maastrichtian of Alaska a nomen dubium, and conservatively regard the Alaskan material as belonging to Edmontosaurus sp.. A phylogenetic analysis of Hadrosauroidea using maximum parsimony further corroborates the sister-taxon relationship between E. regalis and E. annectens. In the strict consensus tree, Hadrosaurus foulkii occurs firmly within the clade comprising all non-lambeosaurine hadrosaurids, supporting the taxonomic scheme that divides Hadrosauridae into Hadrosaurinae and Lambeosaurinae. Within Edmontosaurini, Kerberosaurus is posited as the sister taxon to the clade of Shantungosaurus + Edmontosaurus. The biogeographic reconstruction of Hadrosaurinae in light of the time-calibrated cladogram and probability calculation of ancestral areas for all internal nodes reveals a significantly high probability for the North American origin of the clade. However, the Laramidia–Appalachia dispersals around the Santonian–Campanian boundary, inferred from the biogeographic scenario for the North American origin of Hadrosaurinae, are in conflict with currently accepted paleogeographic models. By contrast, the Asian origin of Hadrosaurinae with its relatively low probability resulting from the biogeographic analysis is worth seriously considering, despite the lack of fossil material from the Santonian and lower Campanian of Asia. Extra fossil collecting in appropriate geographic locations and stratigraphic intervals of Asia and Europe will help to clarify the biogeographic dynamics of hadrosaurine dinosaurs in the near future.
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Affiliation(s)
- Hai Xing
- Beijing Museum of Natural History, Beijing Academy of Science and Technology, Beijing, China
- * E-mail:
| | - Jordan C. Mallon
- Palaeobiology, Canadian Museum of Nature, Ottawa, Ontario, Canada
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20
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Comeault AA, Matute DR. Reinforcement's incidental effects on reproductive isolation between conspecifics. Curr Zool 2016; 62:135-143. [PMID: 29491901 PMCID: PMC5804225 DOI: 10.1093/cz/zow002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 01/11/2016] [Indexed: 12/26/2022] Open
Abstract
Reinforcement—the process whereby maladaptive hybridization leads to the strengthening of prezygotic isolation between species—has a long history in the study of speciation. Because reinforcement affects traits involved in mate choice and fertility, it can have indirect effects on reproductive isolation between populations within species. Here we review examples of these “cascading effects of reinforcement” (CER) and discuss different mechanisms through which they can arise. We discuss three factors that are predicted to influence the potential occurrence of CER: rates of gene flow among populations, the strength of selection acting on the traits involved in reinforcement, and the genetic basis of those traits. We suggest that CER is likely if (1) the rate of gene flow between conspecific populations is low; (2) divergent selection acts on phenotypes involved in reinforcement between sympatric and allopatric populations; and (3) the genetic response to reinforcement differs among conspecific populations subject to parallel reinforcing selection. Future work continuing to address gene flow, selection, and the genetic basis of the traits involved in the reinforcement will help develop a better understanding of reinforcement as a process driving the production of species diversity, both directly and incidentally.
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Affiliation(s)
- Aaron A Comeault
- Biology Department, University of North Carolina, 250 Bell Tower Road, Chapel Hill, NC 27599, USA
| | - Daniel R Matute
- Biology Department, University of North Carolina, 250 Bell Tower Road, Chapel Hill, NC 27599, USA
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Llorente B, D’Andrea L, Rodríguez-Concepción M. Evolutionary Recycling of Light Signaling Components in Fleshy Fruits: New Insights on the Role of Pigments to Monitor Ripening. FRONTIERS IN PLANT SCIENCE 2016; 7:263. [PMID: 27014289 PMCID: PMC4780243 DOI: 10.3389/fpls.2016.00263] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 02/19/2016] [Indexed: 05/05/2023]
Abstract
Besides an essential source of energy, light provides environmental information to plants. Photosensory pathways are thought to have occurred early in plant evolution, probably at the time of the Archaeplastida ancestor, or perhaps even earlier. Manipulation of individual components of light perception and signaling networks in tomato (Solanum lycopersicum) affects the metabolism of ripening fruit at several levels. Most strikingly, recent experiments have shown that some of the molecular mechanisms originally devoted to sense and respond to environmental light cues have been re-adapted during evolution to provide plants with useful information on fruit ripening progression. In particular, the presence of chlorophylls in green fruit can strongly influence the spectral composition of the light filtered through the fruit pericarp. The concomitant changes in light quality can be perceived and transduced by phytochromes (PHYs) and PHY-interacting factors, respectively, to regulate gene expression and in turn modulate the production of carotenoids, a family of metabolites that are relevant for the final pigmentation of ripe fruits. We raise the hypothesis that the evolutionary recycling of light-signaling components to finely adjust pigmentation to the actual ripening stage of the fruit may have represented a selective advantage for primeval fleshy-fruited plants even before the extinction of dinosaurs.
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Affiliation(s)
- Briardo Llorente
- *Correspondence: Briardo Llorente, ; Manuel Rodríguez-Concepción,
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A new horned dinosaur reveals convergent evolution in cranial ornamentation in Ceratopsidae. Curr Biol 2015; 25:1641-8. [PMID: 26051892 DOI: 10.1016/j.cub.2015.04.041] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 04/20/2015] [Accepted: 04/20/2015] [Indexed: 11/22/2022]
Abstract
Ceratopsid (horned) dinosaurs are an iconic group of large-bodied, quadrupedal, herbivorous dinosaurs that evolved in the Late Cretaceous and were largely restricted to western North America [1-5]. Ceratopsids are easily recognized by their cranial ornamentation in the form of nasal and postorbital horns and frill (capped by epiossifications); these structures show high morphological disparity and also represent the largest cranial display structures known to have evolved [2, 4]. Despite their restricted occurrence in time and space, this group has one of the best fossil records within Dinosauria, showing a rapid diversification in horn and frill morphology [1]. Here a new genus and species of chasmosaurine ceratopsid is described based on a nearly complete and three-dimensionally preserved cranium recovered from the uppermost St. Mary River Formation (Maastrichtian) of southwestern Alberta. Regaliceratops peterhewsi gen. et sp. nov. exhibits many unique characters of the frill and is characterized by a large nasal horncore, small postorbital horncores, and massive parietal epiossifications. Cranial morphology, particularly the epiossifications, suggests close affinity with the late Campanian/early Maastrichian taxon Anchiceratops, as well as with the late Maastrichtian taxon Triceratops. A median epiparietal necessitates a reassessment of epiossification homology and results in a more resolved phylogeny. Most surprisingly, Regaliceratops exhibits a suite of cranial ornamentations that are superficially similar to Campanian centrosaurines, indicating both exploration of novel display morphospace in Chasmosaurinae, especially Maastrichtian forms, and convergent evolution in horn morphology with the recently extinct Centrosaurinae. This marks the first time that evolutionary convergence in horn-like display structures has been demonstrated between dinosaur clades, similar to those seen in fossil and extant mammals [6].
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Abstract
A soft tissue structure has been discovered on the head of the duck-billed dinosaur Edmontosaurus. Its similarity to a cock's comb and other sexually dimorphic structures of birds suggests that potential sexual signals existed in these extinct animals.
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Affiliation(s)
- John R Horner
- Museum of the Rockies, Montana State University, Bozeman, MT 59717, USA.
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