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McParland ED, Mitchell JK, Laurence-Chasen JD, Aspinwall LC, Afolabi O, Takahashi K, Ross CF, Gidmark NJ. The Kinematics of Proal Chewing in Rats. Integr Org Biol 2024; 6:obae023. [PMID: 39086740 PMCID: PMC11290364 DOI: 10.1093/iob/obae023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 05/12/2024] [Indexed: 08/02/2024] Open
Abstract
Chewing kinematics are well-documented in several mammal species with fused mandibular symphyses, but relatively understudied in mammals with an unfused symphysis, despite the fact that more than half of extant Mammalia have an unfused mandibular symphysis. The Wistar brown rat (Rattus norvegicus) is widely used in human health research, including studies of mastication or neurological studies where mastication is the output behavior. These animals are known to have unfused mandibular symphyses and proal jaw (rostrocaudal) motion during occlusion, but the lack of high resolution, 3-dimensional analysis of rat chewing leaves the functional significance of symphyseal mobility unknown. We used biplanar fluoroscopy and the X-ray reconstruction of moving morphology workflow to quantify chewing kinematics in 3 brown rats, quantifying overall jaw kinematics, including motions about the temporomandibular joint and unfused mandibular symphysis. During occlusion, the teeth and the mandibular condyle translate almost exclusively anteriorly (proal) during occlusion, with little motion in any other degrees of freedom. At the symphysis, we observed minimal flexion throughout the chew cycle. Overall, there are fundamental differences in jaw kinematics between rats and other mammals and therefore rats are not an appropriate proxy for ancestral mammal jaw mechanics. Additionally, differences between humans and rat chewing kinematics must be considered when using rats as a clinical model for pathological feeding research.
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Affiliation(s)
- E D McParland
- Department of Biology, Knox College, Galesburg, IL 61401, USA
- Department of Ecology, Evolution and Organismal Biology, Brown University, Providence, RI 02912, USA
| | - J K Mitchell
- Department of Biology, Knox College, Galesburg, IL 61401, USA
| | - J D Laurence-Chasen
- Department of Organismal Biology & Anatomy, The University of Chicago, Chicago, IL 60637, USA
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - L C Aspinwall
- Department of Biology, Knox College, Galesburg, IL 61401, USA
| | - O Afolabi
- Department of Biology, Knox College, Galesburg, IL 61401, USA
- College of Medicine, American University of Antigua, Osbourn, Antigua & Barbuda
| | - K Takahashi
- Department of Organismal Biology & Anatomy, The University of Chicago, Chicago, IL 60637, USA
| | - C F Ross
- Department of Organismal Biology & Anatomy, The University of Chicago, Chicago, IL 60637, USA
| | - N J Gidmark
- Department of Biology, Knox College, Galesburg, IL 61401, USA
- Department of Organismal Biology & Anatomy, The University of Chicago, Chicago, IL 60637, USA
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Mao F, Li Z, Wang Z, Zhang C, Rich T, Vickers-Rich P, Meng J. Jurassic shuotheriids show earliest dental diversification of mammaliaforms. Nature 2024; 628:569-575. [PMID: 38570681 DOI: 10.1038/s41586-024-07258-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 02/29/2024] [Indexed: 04/05/2024]
Abstract
Shuotheriids are Jurassic mammaliaforms that possess pseudotribosphenic teeth in which a pseudotalonid is anterior to the trigonid in the lower molar, contrasting with the tribosphenic pattern of therian mammals (placentals, marsupials and kin) in which the talonid is posterior to the trigonid1-4. The origin of the pseudotribosphenic teeth remains unclear, obscuring our perception of shuotheriid affinities and the early evolution of mammaliaforms1,5-9. Here we report a new Jurassic shuotheriid represented by two skeletal specimens. Their complete pseudotribosphenic dentitions allow reidentification of dental structures using serial homology and the tooth occlusal relationship. Contrary to the conventional view1,2,6,10,11, our findings show that dental structures of shuotheriids can be homologized to those of docodontans and partly support homologous statements for some dental structures between docodontans and other mammaliaforms6,12. The phylogenetic analysis based on new evidence removes shuotheriids from the tribosphenic ausktribosphenids (including monotremes) and clusters them with docodontans to form a new clade, Docodontiformes, that is characterized by pseudotribosphenic features. In the phylogeny, docodontiforms and 'holotherians' (Kuehneotherium, monotremes and therians)13 evolve independently from a Morganucodon-like ancestor with triconodont molars by labio-lingual widening their posterior teeth for more efficient food processing. The pseudotribosphenic pattern passed a cusp semitriangulation stage9, whereas the tribosphenic pattern and its precursor went through a stage of cusp triangulation. The two different processes resulted in complex tooth structures and occlusal patterns that elucidate the earliest diversification of mammaliaforms.
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Affiliation(s)
- Fangyuan Mao
- Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
- Division of Paleontology, American Museum of Natural History, New York, NY, USA.
| | - Zhiyu Li
- Inner Mongolia Museum of Natural History, Hohhot, China
| | - Zhili Wang
- Inner Mongolia Museum of Natural History, Hohhot, China
| | - Chi Zhang
- Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Thomas Rich
- Museums Victoria, Melbourne, Victoria, Australia
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, Australia
| | - Patricia Vickers-Rich
- Museums Victoria, Melbourne, Victoria, Australia
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, Australia
- School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
| | - Jin Meng
- Division of Paleontology, American Museum of Natural History, New York, NY, USA.
- Earth and Environmental Sciences, City University of New York, New York, NY, USA.
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3
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Stilson KT, Luo ZX, Li P, Olson S, Ross CF. Three-dimensional mandibular kinematics of mastication in the marsupial Didelphis virginiana. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220548. [PMID: 37839456 PMCID: PMC10577026 DOI: 10.1098/rstb.2022.0548] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 07/26/2023] [Indexed: 10/17/2023] Open
Abstract
Didelphis virginiana (the Virginia opossum) is often used as an extant model for understanding feeding behaviour in Mesozoic mammaliaforms, primarily due to their morphological similarities, including an unfused mandibular symphysis and tribosphenic molars. However, the three-dimensional jaw kinematics of opossum chewing have not yet been fully quantified. We used biplanar videofluoroscopy and the X-Ray Reconstruction of Moving Morphology workflow to quantify mandibular kinematics in four wild-caught opossums feeding on hard (almonds) and soft (cheese cubes) foods. These data were used to test hypotheses regarding the importance of roll versus yaw in chewing by early mammals, and the impact of food material properties (FMPs) on jaw kinematics. The magnitude of roll exceeds that of yaw, but both are necessary for tooth-tooth or tooth-food-tooth contact between complex occlusal surfaces. We confirmed the utility of the four vertical kinematic gape cycle phases identified in tetrapods but we further defined two more in order to capture non-vertical kinematics. Statistical tests support the separation of chew cycle phases into two functional groups: occlusal and non-occlusal phases. The separation of slow close into two (occlusal) phases gives quantitative kinematic support for the long-hypothesized multifunctionality of the tribosphenic molar. This article is part of the theme issue 'Food processing and nutritional assimilation in animals'.
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Affiliation(s)
- Kelsey T. Stilson
- Ecology, Evolution, and Organismal Biology, Brown University, Providence, RI 02912, USA
| | - Zhe-Xi Luo
- Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
| | - Peishu Li
- Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
| | - Selby Olson
- Department of Biology, University of Florida, Gainesville, FL 32610, USA
| | - Callum F. Ross
- Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
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4
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Woodruff ED, Kircher BK, Armfield BA, Levy JK, Bloch JI, Cohn MJ. Domestic cat embryos reveal unique transcriptomes of developing incisor, canine, and premolar teeth. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2022; 338:516-531. [PMID: 35816012 DOI: 10.1002/jez.b.23168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 04/26/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
Division of the dentition into morphologically distinct classes of teeth (incisors, canines, premolars, and molars) and the acquisition of tribosphenic molars facilitated precise occlusion between the teeth early in mammal evolution. Despite the evolutionary and ecological importance of distinct classes of teeth with unique cusp, crest, and basin morphologies, relatively little is known about the genetic basis for the development of different tooth classes within the embryo. Here we investigated genetic differences between developing deciduous incisor, canine, and premolar teeth in the domestic cat (Felis catus), which we propose to be a new model for tooth development. We examined differences in both developmental timing and crown morphology between the three tooth classes. Using RNA sequencing of early bell stage tooth germs, we showed that each of the three deciduous tooth classes possess a unique transcriptional profile. Three notable groups of genes emerged from our differential expression analysis; genes involved in the extracellular matrix (ECM), Wnt pathway signaling, and members of multiple homeobox gene families (Lhx, Dlx, Alx, and Nkx). Our results suggest that ECM genes may play a previously under-appreciated role in shaping the surface of the tooth crown during development. Differential regulation of these genes likely underlies differences in tooth crown shape and size, although subtle temporal differences in development between the tooth germs could also be responsible. This study provides foundational data for future experiments to examine the function of these candidate genes in tooth development to directly test their potential effects on crown morphology.
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Affiliation(s)
- Emily D Woodruff
- Department of Biology, University of Florida, Gainesville, Florida, USA
- Department of Natural History, Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA
| | - Bonnie K Kircher
- Department of Biology, University of Florida, Gainesville, Florida, USA
| | - Brooke A Armfield
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA
| | - Julie K Levy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | - Jonathan I Bloch
- Department of Biology, University of Florida, Gainesville, Florida, USA
- Department of Natural History, Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA
| | - Martin J Cohn
- Department of Biology, University of Florida, Gainesville, Florida, USA
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA
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5
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Harano T, Asahara M. The anteriorization of tooth position underlies the atavism of tooth morphology: Insights into the morphogenesis of mammalian molars. Evolution 2022; 76:2986-3000. [PMID: 36200621 DOI: 10.1111/evo.14637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 08/29/2022] [Accepted: 09/15/2022] [Indexed: 01/22/2023]
Abstract
The evolution and development of complex molars as a key innovation in mammals have long been of interest yet remain poorly understood. With reference to century-old theories and modern findings, we focused on the teeth of pinnipeds (Carnivora) and cetaceans (Cetartiodactyla), which are morphologically simple compared with those of other mammals, and thus can be considered a reversal toward the ancestral state of nonmammalian synapsids. By reconstructing the evolutionary history of tooth complexity for the phylogenies of Carnivora and Cetartiodactyla, we established that a secondary evolution of simple teeth from more complex molars has occurred independently multiple times. Our phylogenetic comparative analyses showed that a simplification in tooth morphology was correlated with a more anterior dentition position relative to the component bones of the upper jaw in both Carnivora and Cetartiodactyla. These results suggest that the anterior shift of tooth position relative to the morphogenetic fields present in the jaw contributed to the evolutionary simplification in molar morphology. Our findings provide insights into the developmental basis of complex mammalian dentition.
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Affiliation(s)
- Tomohiro Harano
- Division of Liberal Arts and Sciences, Aichi Gakuin University, Nisshin, 470-0195, Japan
| | - Masakazu Asahara
- Division of Liberal Arts and Sciences, Aichi Gakuin University, Nisshin, 470-0195, Japan
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Weaver LN, Fulghum HZ, Grossnickle DM, Brightly WH, Kulik ZT, Wilson Mantilla GP, Whitney MR. Multituberculate Mammals Show Evidence of a Life History Strategy Similar to That of Placentals, Not Marsupials. Am Nat 2022; 200:383-400. [DOI: 10.1086/720410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Lucas N. Weaver
- Department of Biology, University of Washington, Seattle, Washington 98195; and Burke Museum of Natural History and Culture, Seattle, Washington 98195
| | - Henry Z. Fulghum
- Department of Biology, University of Washington, Seattle, Washington 98195; and Burke Museum of Natural History and Culture, Seattle, Washington 98195
| | - David M. Grossnickle
- Department of Biology, University of Washington, Seattle, Washington 98195; and Burke Museum of Natural History and Culture, Seattle, Washington 98195
| | - William H. Brightly
- Department of Biology, University of Washington, Seattle, Washington 98195; and Burke Museum of Natural History and Culture, Seattle, Washington 98195
| | - Zoe T. Kulik
- Department of Biology, University of Washington, Seattle, Washington 98195; and Burke Museum of Natural History and Culture, Seattle, Washington 98195
| | - Gregory P. Wilson Mantilla
- Department of Biology, University of Washington, Seattle, Washington 98195; and Burke Museum of Natural History and Culture, Seattle, Washington 98195
| | - Megan R. Whitney
- Department of Biology, University of Washington, Seattle, Washington 98195; and Burke Museum of Natural History and Culture, Seattle, Washington 98195
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138
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7
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Beck RM, Voss RS, Jansa SA. Craniodental Morphology and Phylogeny of Marsupials. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2022. [DOI: 10.1206/0003-0090.457.1.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Robin M.D. Beck
- School of Science, Engineering and Environment University of Salford, U.K. School of Biological, Earth & Environmental Sciences University of New South Wales, Australia Division of Vertebrate Zoology (Mammalogy) American Museum of Natural History
| | - Robert S. Voss
- Division of Vertebrate Zoology (Mammalogy) American Museum of Natural History
| | - Sharon A. Jansa
- Bell Museum and Department of Ecology, Evolution, and Behavior University of Minnesota
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8
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An African Radiation of ‘Dryolestoidea’ (Donodontidae, Cladotheria) and its Significance for Mammalian Evolution. J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09613-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Evolution and development of the mammalian multicuspid teeth. J Oral Biosci 2022; 64:165-175. [DOI: 10.1016/j.job.2022.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 11/20/2022]
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10
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New Specimens of Reigitherium bunodontum from the Late Cretaceous La Colonia Formation, Patagonia, Argentina and Meridiolestidan Diversity in South America. J MAMM EVOL 2021. [DOI: 10.1007/s10914-021-09585-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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11
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Grossnickle DM, Weaver LN, Jäger KRK, Schultz JA. The evolution of anteriorly directed molar occlusion in mammals. Zool J Linn Soc 2021. [DOI: 10.1093/zoolinnean/zlab039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Abstract
In non-mammalian synapsids and early mammals, evolutionary transformations in the feeding and hearing apparatuses are posited to have been prerequisites for the radiation of extant mammals. Unlike most vertebrates, including many early synapsids, mammals have precise dental occlusion, a lower jaw composed of one bone, and middle ear ossicles derived from ancestral jaw bones. We illuminate a related functional transition: therian mammals (eutherians and metatherians) evolved anteriorly directed chewing strokes, which are absent in other synapsid lineages. Anteriorly directed jaw movement during occlusion necessitates anteriorly directed muscle force vectors, and we posit that a shift in muscle orientation is reflected in the fossil record by the evolutionary appearance of a posteriorly positioned angular process in cladotherians (therians and their close kin). Anteriorly directed occlusion might have been absent in earlier synapsids because of the presence of attached middle ear elements in the posterior region of the jaw that prohibited the posterior insertion of jaw musculature. These changes to the masticatory apparatus in cladotherians are likely to have permitted the evolution of novel masticatory movements, including grinding in both the anterior and medial directions (e.g. rodents and ungulates, respectively). Thus, this evolutionary transition might have been a crucial prerequisite for the dietary diversification of therians.
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Affiliation(s)
- David M Grossnickle
- Department of Biology, Life Sciences Building, University of Washington, Seattle, WA, USA
| | - Lucas N Weaver
- Department of Biology, Life Sciences Building, University of Washington, Seattle, WA, USA
| | - Kai R K Jäger
- Section Palaeontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, Bonn, Germany
| | - Julia A Schultz
- Section Palaeontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, Bonn, Germany
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12
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Saeki N, Inui-Yamamoto C, Kuraki M, Itoh S, Inubushi T, Okamoto M, Akiyama S, Wakisaka S, Abe M. Senescence-accelerated mouse prone 8 (SAMP8) mice exhibit reduced entoconid in the lower second molar. Arch Oral Biol 2021; 128:105172. [PMID: 34058725 DOI: 10.1016/j.archoralbio.2021.105172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/18/2021] [Accepted: 05/24/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The position and size of the major cusps in mammalian molars are arranged in a characteristic pattern that depends on taxonomy. In humans, the cusp which locates distally within each molar is smaller than the mesially located cusp, which is referred to as "distal reduction". Although this concept has been well-recognized, it is still unclear how this reduction occurs. Current study examined whether senescence-accelerating mouse prone 8 (SAMP8) mice could be a possible animal model for studying how the mammalian molar cusp size is determined. DESIGN SAMP8 mice were compared with parental control (SAMR1) mice. Microcomputed tomography images of young and aged mice were captured to observe molar cusp morphologies. Cusp height from cement-enamel junction and mesio-distal length of molars were measured. The statistical comparison of the measurements was performed by Mann-Whitney U test. RESULTS SAMP8 mice showed reduced development of the disto-lingual cusp (entoconid) of lower second molar when compared with SAMR1 mice. The enamel thickness and structure was disturbed at entoconid, and aged SAMP8 mice displayed severe wear of the entoconid in lower second molar. These phenotypes were observed on both sides of the lower second molar. CONCLUSIONS In addition to the general senescence phenotype observed in SAMP8 mice, this strain may genetically possess molar cusp phenotypes which is determined prenatally. Further, SAMP8 mice would be a potential model strain to study the genetic causes of the distal reduction of molar cusp size.
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Affiliation(s)
- Naoya Saeki
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Yamada-oka 1-8, Suita, Osaka, Japan; Division of Special Care Dentistry, Osaka University Dental Hospital, Osaka, Japan
| | - Chizuko Inui-Yamamoto
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Yamada-oka 1-8, Suita, Osaka, Japan
| | - Moe Kuraki
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Yamada-oka 1-8, Suita, Osaka, Japan
| | - Shousaku Itoh
- Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Toshihiro Inubushi
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Motoki Okamoto
- Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Shigehisa Akiyama
- Division of Special Care Dentistry, Osaka University Dental Hospital, Osaka, Japan
| | - Satoshi Wakisaka
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Yamada-oka 1-8, Suita, Osaka, Japan
| | - Makoto Abe
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Yamada-oka 1-8, Suita, Osaka, Japan.
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Martinelli AG, Soto-Acuña S, Goin FJ, Kaluza J, Bostelmann JE, Fonseca PHM, Reguero MA, Leppe M, Vargas AO. New cladotherian mammal from southern Chile and the evolution of mesungulatid meridiolestidans at the dusk of the Mesozoic era. Sci Rep 2021; 11:7594. [PMID: 33828193 PMCID: PMC8027844 DOI: 10.1038/s41598-021-87245-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/24/2021] [Indexed: 11/17/2022] Open
Abstract
In the last decades, several discoveries have uncovered the complexity of mammalian evolution during the Mesozoic Era, including important Gondwanan lineages: the australosphenidans, gondwanatherians, and meridiolestidans (Dryolestoidea). Most often, their presence and diversity is documented by isolated teeth and jaws. Here, we describe a new meridiolestidan mammal, Orretherium tzen gen. et sp. nov., from the Late Cretaceous of southern Chile, based on a partial jaw with five cheek teeth in locis and an isolated upper premolar. Phylogenetic analysis places Orretherium as the earliest divergence within Mesungulatidae, before other forms such as the Late Cretaceous Mesungulatum and Coloniatherium, and the early Paleocene Peligrotherium. The in loco tooth sequence (last two premolars and three molars) is the first recovered for a Cretaceous taxon in this family and suggests that reconstructed tooth sequences for other Mesozoic mesungulatids may include more than one species. Tooth eruption and replacement show that molar eruption in mesungulatids is heterochronically delayed with regard to basal dryolestoids, with therian-like simultaneous eruption of the last premolar and last molar. Meridiolestidans seem endemic to Patagonia, but given their diversity and abundance, and the similarity of vertebrate faunas in other regions of Gondwana, they may yet be discovered in other continents.
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Affiliation(s)
- Agustín G Martinelli
- CONICET-Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Av. Ángel Gallardo 470, C1405DJR, CABA, Argentina.
- Red Paleontológica U-Chile, Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7750000, Ñuñoa, Santiago, Chile.
| | - Sergio Soto-Acuña
- Red Paleontológica U-Chile, Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7750000, Ñuñoa, Santiago, Chile.
- KayTreng Consultores SpA, José Domingo Cañas 1640, Apt. 1502, 7750000, Ñuñoa, Santiago, Chile.
| | - Francisco J Goin
- CONICET-División Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
| | - Jonatan Kaluza
- Red Paleontológica U-Chile, Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7750000, Ñuñoa, Santiago, Chile
- Fundación de Historia Natural Félix de Azara, Universidad Maimónides, Hidalgo 775, C1405BCK, CABA, Argentina
| | - J Enrique Bostelmann
- Instituto de Ciencias de la Tierra, Facultad de Ciencias, Universidad Austral de Chile, Los Laureles s/n, 5090000, Valdivia, Chile
- Programa de Doctorado en Ciencias Mención Ecología y Evolución, Universidad Austral de Chile, Los Laureles s/n, 5090000, Valdivia, Chile
- Museo Regional de Aysén, Kilómetro 3 camino a Coyhaique Alto, Coyhaique, Región de Aysén, Chile
| | - Pedro H M Fonseca
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Agronomia, Porto Alegre, RS, 91501-970, Brazil
| | - Marcelo A Reguero
- CONICET-División Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
| | - Marcelo Leppe
- Laboratorio de Paleobiología de Antártica y Patagonia, Instituto Antártico Chileno, Plaza Muñoz Gamero 1055, 6200000, Punta Arenas, Chile
| | - Alexander O Vargas
- Red Paleontológica U-Chile, Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7750000, Ñuñoa, Santiago, Chile
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14
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Celik MA, Phillips MJ. Conflict Resolution for Mesozoic Mammals: Reconciling Phylogenetic Incongruence Among Anatomical Regions. Front Genet 2020; 11:0651. [PMID: 32774343 PMCID: PMC7381353 DOI: 10.3389/fgene.2020.00651] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 05/28/2020] [Indexed: 11/13/2022] Open
Abstract
The evolutionary history of Mesozoic mammaliaformes is well studied. Although the backbone of their phylogeny is well resolved, the placement of ecologically specialized groups has remained uncertain. Functional and developmental covariation has long been identified as an important source of phylogenetic error, yet combining incongruent morphological characters altogether is currently a common practice when reconstructing phylogenetic relationships. Ignoring incongruence may inflate the confidence in reconstructing relationships, particularly for the placement of highly derived and ecologically specialized taxa, such as among australosphenidans (particularly, crown monotremes), haramiyidans, and multituberculates. The alternative placement of these highly derived clades can alter the taxonomic constituency and temporal origin of the mammalian crown group. Based on prior hypotheses and correlated homoplasy analyses, we identified cheek teeth and shoulder girdle character complexes as having a high potential to introduce phylogenetic error. We showed that incongruence among mandibulodental, cranial, and postcranial anatomical partitions for the placement of the australosphenidans, haramiyids, and multituberculates could largely be explained by apparently non-phylogenetic covariance from cheek teeth and shoulder girdle characters. Excluding these character complexes brought agreement between anatomical regions and improved the confidence in tree topology. These results emphasize the importance of considering and ameliorating major sources of bias in morphological data, and we anticipate that these will be valuable for confidently integrating morphological and molecular data in phylogenetic and dating analyses.
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Affiliation(s)
- Mélina A. Celik
- School of Biology and Environmental Science, Queensland University of Technology, Brisbane, QLD, Australia
| | - Matthew J. Phillips
- School of Biology and Environmental Science, Queensland University of Technology, Brisbane, QLD, Australia
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15
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Grossnickle DM. Jaw roll and jaw yaw in early mammals. Nature 2020; 582:E6-E8. [PMID: 32555493 DOI: 10.1038/s41586-020-2365-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 04/01/2020] [Indexed: 11/09/2022]
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16
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Mao F, Hu Y, Li C, Wang Y, Chase MH, Smith AK, Meng J. Integrated hearing and chewing modules decoupled in a Cretaceous stem therian mammal. Science 2019; 367:305-308. [PMID: 31806694 DOI: 10.1126/science.aay9220] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 11/21/2019] [Indexed: 12/13/2022]
Abstract
On the basis of multiple skeletal specimens from Liaoning, China, we report a new genus and species of Cretaceous stem therian mammal that displays decoupling of hearing and chewing apparatuses and functions. The auditory bones, including the surangular, have no bone contact with the ossified Meckel's cartilage; the latter is loosely lodged on the medial rear of the dentary. This configuration probably represents the initial morphological stage of the definitive mammalian middle ear. Evidence shows that hearing and chewing apparatuses have evolved in a modular fashion. Starting as an integrated complex in non-mammaliaform cynodonts, the two modules, regulated by similar developmental and genetic mechanisms, eventually decoupled during the evolution of mammals, allowing further improvement for more efficient hearing and mastication.
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Affiliation(s)
- Fangyuan Mao
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China. .,CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China.,Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - Yaoming Hu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
| | - Chuankui Li
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.,CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
| | - Yuanqing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.,CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
| | - Morgan Hill Chase
- Microscopy and Imaging Facility, American Museum of Natural History, New York, NY 10024, USA
| | - Andrew K Smith
- Microscopy and Imaging Facility, American Museum of Natural History, New York, NY 10024, USA
| | - Jin Meng
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA. .,Earth and Environmental Sciences, Graduate Center, City University of New York, New York, NY 10016, USA
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17
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Chen M, Strömberg CAE, Wilson GP. Assembly of modern mammal community structure driven by Late Cretaceous dental evolution, rise of flowering plants, and dinosaur demise. Proc Natl Acad Sci U S A 2019; 116:9931-9940. [PMID: 31036651 PMCID: PMC6525522 DOI: 10.1073/pnas.1820863116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The long-standing view that Mesozoic mammaliaforms living in dinosaur-dominated ecosystems were ecologically constrained to small size and insectivory has been challenged by astonishing fossil discoveries over the last three decades. By studying these well-preserved early mammaliaform specimens, paleontologists now agree that mammaliaforms underwent ecomorphological diversification during the Mesozoic Era. This implies that Mesozoic mammaliaform communities had ecological structure and breadth that were comparable to today's small-bodied mammalian communities. However, this hypothesis remains untested in part because the primary focus of most studies is on individual taxa. Here, we present a study quantifying the ecological structure of Mesozoic mammaliaform communities with the aim of identifying evolutionary and ecological drivers that influenced the deep-time assembly of small-bodied mammaliaform communities. We used body size, dietary preference, and locomotor mode to establish the ecospace occupation of 98 extant, small-bodied mammalian communities from diverse biomes around the world. We calculated ecological disparity and ecological richness to measure the magnitude of ecological differences among species in a community and the number of different eco-cells occupied by species of a community, respectively. This modern dataset served as a reference for analyzing five exceptionally preserved, extinct mammaliaform communities (two Jurassic, two Cretaceous, one Eocene) from Konservat-Lagerstätten. Our results indicate that the interplay of at least three factors, namely the evolution of the tribosphenic molar, the ecological rise of angiosperms, and potential competition with other vertebrates, may have been critical in shaping the ecological structure of small-bodied mammaliaform communities through time.
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Affiliation(s)
- Meng Chen
- School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China;
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (CAS), Nanjing 210008, China
| | - Caroline A E Strömberg
- Department of Biology, University of Washington, Seattle, WA 98195-1800
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195-3010
| | - Gregory P Wilson
- Department of Biology, University of Washington, Seattle, WA 98195-1800;
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195-3010
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18
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Reigitherium (Meridiolestida, Mesungulatoidea) an Enigmatic Late Cretaceous Mammal from Patagonia, Argentina: Morphology, Affinities, and Dental Evolution. J MAMM EVOL 2018. [DOI: 10.1007/s10914-018-9437-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Conith AJ, Imburgia MJ, Crosby AJ, Dumont ER. The functional significance of morphological changes in the dentitions of early mammals. J R Soc Interface 2017; 13:rsif.2016.0713. [PMID: 28339367 DOI: 10.1098/rsif.2016.0713] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 10/18/2016] [Indexed: 11/12/2022] Open
Abstract
The Mesozoic marked a time of experimentation in the tooth morphology of early mammals. One particular experiment involved the movement of three points, or cusps, on the surface of a molar tooth from a line into a triangle. This transition is exemplified by two extinct insectivorous mammals, Morganucodon (cusps in a line) and Kuehneotherium (cusps in a triangle). Here we test whether this difference in cusp arrangement, alongside cusp heights and angles between cusps, is associated with differences in the ability of the teeth to fracture proxy-insect prey. We gathered measurements from molar teeth of both species and used them to create physical models. We then measured the force, time and energy at fracture and peak force, and the amount of damage inflicted by the models on hard and soft gels encased in a tough film that mimicked the material properties of insects. The Morganucodon model required less force and energy to fracture hard gels and reach peak force compared with KuehneotheriumKuehneotherium required a similar time, force and energy to fracture soft gels but reduced the time, force and energy to reach peak force. More importantly, Kuehneotherium also inflicted more damage to both the hard and the soft gels. These results suggest that changes in dental morphology in some early mammals was driven primarily by selection for maximizing damage, and secondarily for maximizing biomechanical efficiency for a given food material property.
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Affiliation(s)
- Andrew J Conith
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Michael J Imburgia
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Alfred J Crosby
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Elizabeth R Dumont
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003, USA
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20
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Grossnickle DM. The evolutionary origin of jaw yaw in mammals. Sci Rep 2017; 7:45094. [PMID: 28322334 PMCID: PMC5359619 DOI: 10.1038/srep45094] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 02/17/2017] [Indexed: 11/17/2022] Open
Abstract
Theria comprises all but three living mammalian genera and is one of the most ecologically pervasive clades on Earth. Yet, the origin and early history of therians and their close relatives (i.e., cladotherians) remains surprisingly enigmatic. A critical biological function that can be compared among early mammal groups is mastication. Morphometrics and modeling analyses of the jaws of Mesozoic mammals indicate that cladotherians evolved musculoskeletal anatomies that increase mechanical advantage during jaw rotation around a dorsoventrally-oriented axis (i.e., yaw) while decreasing the mechanical advantage of jaw rotation around a mediolaterally-oriented axis (i.e., pitch). These changes parallel molar transformations in early cladotherians that indicate their chewing cycles included significant transverse movement, likely produced via yaw rotation. Thus, I hypothesize that cladotherian molar morphologies and musculoskeletal jaw anatomies evolved concurrently with increased yaw rotation of the jaw during chewing cycles. The increased transverse movement resulting from yaw rotation may have been a crucial evolutionary prerequisite for the functionally versatile tribosphenic molar morphology, which underlies the molars of all therians and is retained by many extant clades.
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Affiliation(s)
- David M Grossnickle
- University of Chicago, Committee on Evolutionary Biology, Chicago, 60637, USA
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21
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Kallistová A, Horáček I, Šlouf M, Skála R, Fridrichová M. Mammalian enamel maturation: Crystallographic changes prior to tooth eruption. PLoS One 2017; 12:e0171424. [PMID: 28196135 PMCID: PMC5308864 DOI: 10.1371/journal.pone.0171424] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 01/20/2017] [Indexed: 01/26/2023] Open
Abstract
Using the distal molar of a minipig as a model, we studied changes in the microstructural characteristics of apatite crystallites during enamel maturation (16-23 months of postnatal age), and their effects upon the mechanical properties of the enamel coat. The slow rate of tooth development in a pig model enabled us to reveal essential heterochronies in particular components of the maturation process. The maturation changes began along the enamel-dentine junction (EDJ) of the trigonid, spreading subsequently to the outer layers of the enamel coat to appear at the surface zone with a 2-month delay. Correspondingly, at the distal part of the tooth the timing of maturation processes is delayed by 3-5 month compared to the mesial part of the tooth. The early stage of enamel maturation (16-20 months), when the enamel coat is composed almost exclusively of radial prismatic enamel, is characterized by a gradual increase in crystallite thickness (by a mean monthly increment of 3.8 nm); and an increase in the prism width and thickness of crystals composed of elementary crystallites. The late stage of maturation (the last two months prior to tooth eruption), marked with the rapid appearance of the interprismatic matrix (IPM) during which the crystals densely infill spaces between prisms, is characterized by an abrupt decrease in microstrain and abrupt changes in the micromechanical properties of the enamel: a rapid increase in its ability to resist long-term load and its considerable hardening. The results suggest that in terms of crystallization dynamics the processes characterizing the early and late stage of mammalian enamel maturation represent distinct entities. In regards to common features with enamel formation in the tribosphenic molar we argue that the separation of these processes could be a common apomorphy of mammalian amelogenetic dynamics in general.
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Affiliation(s)
- Anna Kallistová
- Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, Czech Republic
- Institute of Geology of the CAS, v.v.i., Rozvojová 269, Prague 6, Czech Republic
| | - Ivan Horáček
- Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, Czech Republic
- * E-mail:
| | - Miroslav Šlouf
- Institute of Macromolecular Chemistry of CAS v.v.i., Heyrovského náměstí 2, Prague 6, Czech Republic
| | - Roman Skála
- Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, Czech Republic
- Institute of Geology of the CAS, v.v.i., Rozvojová 269, Prague 6, Czech Republic
| | - Michaela Fridrichová
- Institute of Geology of the CAS, v.v.i., Rozvojová 269, Prague 6, Czech Republic
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22
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Solé F, Ladevèze S. Evolution of the hypercarnivorous dentition in mammals (Metatheria,Eutheria) and its bearing on the development of tribosphenic molars. Evol Dev 2017; 19:56-68. [DOI: 10.1111/ede.12219] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Floréal Solé
- Evo-Devo of Vertebrate Dentition; Institut de Génomique Fonctionnelle de Lyon; Ecole Normale Supérieure de Lyon; Université de Lyon; UCBL 1 CNRS, Lyon France
| | - Sandrine Ladevèze
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P, UMR 7207); Sorbonne Universités MNHN CNRS UPMC-Paris6; Muséum national d'Histoire naturelle; 57 rue Cuvier CP 38 F-75005 Paris France
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23
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Han G, Meng J. A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian ‘symmetrodontans’. Zool J Linn Soc 2016. [DOI: 10.1111/zoj.12416] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gang Han
- Hainan Tropical Ocean University; Sanya; Hainan Province 572022 China
- Paleontology Center; Bohai University; Jinzhou Liaoning Province; 121013 China
| | - Jin Meng
- Division of Paleontology; American Museum of Natural History; New York NY 10024 USA
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24
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Bi S, Zheng X, Meng J, Wang X, Robinson N, Davis B. A new symmetrodont mammal (Trechnotheria: Zhangheotheriidae) from the Early Cretaceous of China and trechnotherian character evolution. Sci Rep 2016; 6:26668. [PMID: 27215593 PMCID: PMC4877676 DOI: 10.1038/srep26668] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/06/2016] [Indexed: 11/09/2022] Open
Abstract
We report the discovery of Anebodon luoi, a new genus and species of zhangheotheriid symmetrodont mammal from the Lujiatun site of the Lower Cretaceous Yixian Formation, China. The fossil is represented by an associated partial skull and dentaries with a nearly complete dentition, and with a dental formula of I4/3 C1/1 P5/4 M3/4. This new taxon lacks the high molar count typical of derived symmetrodonts, differing from the well-represented zhangheotheriids Zhangheotherium and Maotherium in having a postcanine dental formula that resembles more primitive tinodontid symmetrodonts on the one hand, and sister taxa to therians such as Peramus on the other. Upper and lower distal premolars are strongly molariform and are captured undergoing replacement, clarifying positional homology among related taxa. We also describe the rostrum and, for the first time in a symmetrodont, much of the orbital mosaic. Importantly, our new taxon occupies a basal position within the Zhangheotheriidae and permits discussion of trechnotherian character evolution, ultimately shedding additional light on the evolution of therians.
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Affiliation(s)
- Shundong Bi
- Department of Biology, Indiana University of Pennsylvania, Indiana, PA 15705, USA
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
| | - Xiaoting Zheng
- Shandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China
- Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276000, China
| | - Jin Meng
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th St., New York, NY 10024, USA
| | - Xiaoli Wang
- Shandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China
- Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276000, China
| | - Nicole Robinson
- Department of Biology, Indiana University of Pennsylvania, Indiana, PA 15705, USA
| | - Brian Davis
- Department of Anatomical Sciences and Neurobiology, University of Louisville, 511 S. Floyd St., Louisville, KY 40202, USA
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25
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Lovegrove BG. A phenology of the evolution of endothermy in birds and mammals. Biol Rev Camb Philos Soc 2016; 92:1213-1240. [DOI: 10.1111/brv.12280] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Barry G. Lovegrove
- School of Life Sciences; University of KwaZulu-Natal; P/Bag X01 Scottsville Pietermaritzburg 3209 South Africa
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26
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Affiliation(s)
- Ivan Calandra
- GEGENAA - EA 3795; Université de Reims Champagne-Ardenne; CREA - 2 esplanade Roland Garros 51100 Reims France
| | - Gildas Merceron
- iPHEP UMR 7262; CNRS & Université de Poitiers; Bat. B35 - TSA-51106, 6 rue M. Brunet 86073 Poitiers France
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27
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Gutzwiller SC, Hunter JP. Evolution and function of the upper molar talon and its dietary implications in microbats. J Morphol 2015; 276:1368-76. [PMID: 26473768 DOI: 10.1002/jmor.20424] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 06/02/2015] [Accepted: 07/05/2015] [Indexed: 11/06/2022]
Abstract
The evolution of mammalian molars has been marked by transitions representing significant changes in shape and function. One such transition is the addition and elaboration of the talon, the distolingual region of the ancestral tribosphenic upper molar of therian mammals and some extinct relatives. This study uses suborder Microchiroptera as a case study to explore the adaptive implications of the expansion of the talon on the tribosphenic molar, specifically focusing on the talon's role in the compression and shear of food during breakdown. Three-dimensional computer renderings of casts of the upper left first molars were created for microbat species of a variety of dietary categories (frugivore, etc.) and physical properties of food (hard and soft). Relief Index (RFI) was measured to estimate the topography and function of the whole tooth and of the talon and trigon (the remaining primitive tribosphenic region) individually, in order to examine 1) how the shape of the whole tooth, trigon, and talon reflects the compromise between their crushing and shearing functions, 2) how whole tooth, trigon, and talon function differs according to diet, and 3) how the presence of the talon affects overall molar function. Results suggest that RFI of both the whole tooth and the trigon varies according to dietary groups, with frugivores having greater crushing function when compared with the other groups. The talon, however, consistently has low RFI (a flatter topography), and its presence lowers the RFI of the whole tooth across all dietary categories, suggesting that the talon is primarily functioning in crushing during food breakdown. The potential benefits of a crushing talon for microbats of various dietary groups are discussed.
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Affiliation(s)
- Sarah C Gutzwiller
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio
| | - John P Hunter
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University Newark, Newark, Ohio
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28
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Williamson TE, Brusatte SL, Wilson GP. The origin and early evolution of metatherian mammals: the Cretaceous record. Zookeys 2014:1-76. [PMID: 25589872 PMCID: PMC4284630 DOI: 10.3897/zookeys.465.8178] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 11/16/2014] [Indexed: 11/12/2022] Open
Abstract
Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. Our understanding of this group has increased greatly over the past 20 years, with the discovery of new specimens and the application of new analytical tools. Here we provide a review of the phylogenetic relationships of metatherians with respect to other mammals, discuss the taxonomic definition and diagnosis of Metatheria, outline the Cretaceous history of major metatherian clades, describe the paleobiology, biogeography, and macroevolution of Cretaceous metatherians, and provide a physical and climatic background of Cretaceous metatherian faunas. Metatherians are a clade of boreosphendian mammals that must have originated by the Late Jurassic, but the first unequivocal metatherian fossil is from the Early Cretaceous of Asia. Metatherians have the distinctive tightly interlocking occlusal molar pattern of tribosphenic mammals, but differ from Eutheria in their dental formula and tooth replacement pattern, which may be related to the metatherian reproductive process which includes an extended period of lactation followed by birth of extremely altricial young. Metatherians were widespread over Laurasia during the Cretaceous, with members present in Asia, Europe, and North America by the early Late Cretaceous. In particular, they were taxonomically and morphologically diverse and relatively abundant in the Late Cretaceous of western North America, where they have been used to examine patterns of biogeography, macroevolution, diversification, and extinction through the Late Cretaceous and across the Cretaceous-Paleogene (K-Pg) boundary. Metatherian diversification patterns suggest that they were not strongly affected by a Cretaceous Terrestrial Revolution, but they clearly underwent a severe extinction across the K-Pg boundary.
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Affiliation(s)
- Thomas E Williamson
- New Mexico Museum of Natural History and Science, 1801 Mountain Road, NW, Albuquerque, New Mexico 87104-1375, USA
| | | | - Gregory P Wilson
- Department of Biology and Burke Museum of Natural History and Culture, 24 Kincaid Hall, University of Washington, Seattle, Washington 98195-1800, USA
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29
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Schultz JA, Martin T. Function of pretribosphenic and tribosphenic mammalian molars inferred from 3D animation. Naturwissenschaften 2014; 101:771-81. [PMID: 25091547 DOI: 10.1007/s00114-014-1214-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/11/2014] [Accepted: 07/17/2014] [Indexed: 12/01/2022]
Abstract
Appearance of the tribosphenic molar in the Late Jurassic (160 Ma) is a crucial innovation for food processing in mammalian evolution. This molar type is characterized by a protocone, a talonid basin and a two-phased chewing cycle, all of which are apomorphic. In this functional study on the teeth of Late Jurassic Dryolestes leiriensis and the living marsupial Monodelphis domestica, we demonstrate that pretribosphenic and tribosphenic molars show fundamental differences of food reduction strategies, representing a shift in dental function during the transition of tribosphenic mammals. By using the Occlusal Fingerprint Analyser (OFA), we simulated the chewing motions of the pretribosphenic Dryolestes that represents an evolutionary precursor condition to such tribosphenic mammals as Monodelphis. Animation of chewing path and detection of collisional contacts between virtual models of teeth suggests that Dryolestes differs from the classical two-phased chewing movement of tribosphenidans, due to the narrowing of the interdental space in cervical (crown-root transition) direction, the inclination angle of the hypoflexid groove, and the unicuspid talonid. The pretribosphenic chewing cycle is equivalent to phase I of the tribosphenic chewing cycle, but the former lacks phase II of the tribosphenic chewing. The new approach can analyze the chewing cycle of the jaw by using polygonal 3D models of tooth surfaces, in a way that is complementary to the electromyography and strain gauge studies of muscle function of living animals. The technique allows alignment and scaling of isolated fossil teeth and utilizes the wear facet orientation and striation of the teeth to reconstruct the chewing path of extinct mammals.
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Affiliation(s)
- Julia A Schultz
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany,
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30
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O’Meara RN, Thompson RS. Were There Miocene Meridiolestidans? Assessing the Phylogenetic Placement of Necrolestes patagonensis and the Presence of a 40 Million Year Meridiolestidan Ghost Lineage. J MAMM EVOL 2014. [DOI: 10.1007/s10914-013-9252-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Kusuhashi N, Tsutsumi Y, Saegusa H, Horie K, Ikeda T, Yokoyama K, Shiraishi K. A new Early Cretaceous eutherian mammal from the Sasayama Group, Hyogo, Japan. Proc Biol Sci 2013; 280:20130142. [PMID: 23536594 DOI: 10.1098/rspb.2013.0142] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We here describe a new Early Cretaceous (early Albian) eutherian mammal, Sasayamamylos kawaii gen. et sp. nov., from the 'Lower Formation' of the Sasayama Group, Hyogo Prefecture, Japan. Sasayamamylos kawaii is characterized by a robust dentary, a distinct angle on the ventral margin of the dentary at the posterior end of the mandibular symphysis, a lower dental formula of 3-4 : 1 : 4 : 3, a robust lower canine, a non-molariform lower ultimate premolar, and a secondarily reduced entoconid on the molars. To date, S. kawaii is the earliest known eutherian mammal possessing only four premolars, which demonstrates that the reduction in the premolar count in eutherians started in the late Early Cretaceous. The occurrence of S. kawaii implies that the relatively rapid diversification of eutherians in the mid-Cretaceous had already started by the early Albian.
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Affiliation(s)
- Nao Kusuhashi
- Department of Earth's Evolution and Environment, Graduate School of Science and Engineering, Ehime University, Ehime 790-8577, Japan.
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Averianov AO, Martin T, Lopatin AV. A new phylogeny for basal Trechnotheria and Cladotheria and affinities of South American endemic Late Cretaceous mammals. Naturwissenschaften 2013; 100:311-26. [PMID: 23494201 DOI: 10.1007/s00114-013-1028-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 02/22/2013] [Accepted: 02/26/2013] [Indexed: 11/25/2022]
Abstract
The endemic South American mammals Meridiolestida, considered previously as dryolestoid cladotherians, are found to be non-cladotherian trechnotherians related to spalacotheriid symmetrodontans based on a parsimony analysis of 137 morphological characters among 44 taxa. Spalacotheriidae is the sister taxon to Meridiolestida, and the latter clade is derived from a primitive spalacolestine that migrated to South America from North America at the beginning of the Late Cretaceous. Meridiolestida survived until the early Paleocene (Peligrotherium) and early Miocene (Necrolestes) in South America, and their extinction is probably linked to the increasing competition with metatherian and eutherian tribosphenic mammals. The clade Meridiolestida plus Spalacotheriidae is the sister taxon to Cladotheria and forms a new clade Alethinotheria. Alethinotheria and its sister taxon Zhangheotheria, new clade (Zhangheotheriidae plus basal taxa), comprise Trechnotheria. Cladotheria is divided into Zatheria (plus stem taxa, including Amphitherium) and Dryolestida, including Dryolestidae and a paraphyletic array of basal dryolestidans (formerly classified as "Paurodontidae"). The South American Vincelestes and Groebertherium are basal dryolestidans.
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Affiliation(s)
- Alexander O Averianov
- Zoological Institute of the Russian Academy of Sciences, Universitetskaya nab. 1, 199034 Saint Petersburg, Russia.
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Persistence of a Mesozoic, non-therian mammalian lineage (Gondwanatheria) in the mid-Paleogene of Patagonia. Naturwissenschaften 2012; 99:449-63. [DOI: 10.1007/s00114-012-0919-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 04/23/2012] [Accepted: 04/25/2012] [Indexed: 10/28/2022]
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