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The earliest-known mammaliaform fossil from Greenland sheds light on origin of mammals.
Proc Natl Acad Sci U S A. 2020 10 27; 117(43):26861-26867.PN

Abstract

Synapsids are unique in having developed multirooted teeth and complex occlusions. These innovations evolved in at least two lineages of mammaliamorphs (Tritylodontidae and Mammaliaformes). Triassic fossils demonstrate that close to the origins of mammals, mammaliaform precursors were "experimenting" with tooth structure and function, resulting in novel patterns of occlusion. One of the most surprising examples of such adaptations is present in the haramiyidan clade, which differed from contemporary mammaliaforms in having two rows of cusps on molariform crowns adapted to omnivorous/herbivorous feeding. However, the origin of the multicusped tooth pattern present in haramiyidans has remained enigmatic. Here we describe the earliest-known mandibular fossil of a mammaliaform with double molariform roots and a crown with two rows of cusps from the Late Triassic of Greenland. The crown morphology is intermediate between that of morganucodontans and haramiyidans and suggests the derivation of the multicusped molariforms of haramiyidans from the triconodont molar pattern seen in morganucodontids. Although it is remarkably well documented in the fossil record, the significance of tooth root division in mammaliaforms remains enigmatic. The results of our biomechanical analyses (finite element analysis [FEA]) indicate that teeth with two roots can better withstand stronger mechanical stresses like those resulting from tooth occlusion, than teeth with a single root.

Authors+Show Affiliations

Institute of Paleobiology, Polish Academy of Sciences, 00-818 Warsaw, Poland.Faculty of Power and Aeronautical Engineering, Institute of Aeronautics and Applied Mechanics, Warsaw University of Technology, 00-665 Warsaw, Poland.Department of Paleobiology and Evolution, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, 02-089 Warsaw, Poland.Institute of Paleobiology, Polish Academy of Sciences, 00-818 Warsaw, Poland. Department of Earth Sciences, University of Oxford, OX1 3AN Oxford, United Kingdom.Institute of Paleobiology, Polish Academy of Sciences, 00-818 Warsaw, Poland.Geological Section, Natural History Museum of Denmark, University of Copenhagen, DK-2100 Copenhagen, Denmark. Fur Museum, 7884 Fur, Denmark.Department of Cranio-Maxillofacial Surgery, Oral Surgery and Implantology, Medical University of Warsaw, 02-091 Warsaw, Poland.Faculty of Power and Aeronautical Engineering, Institute of Aeronautics and Applied Mechanics, Warsaw University of Technology, 00-665 Warsaw, Poland.Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, 752 36 Uppsala, Sweden grzegorz.niedzwiedzki@ebc.uu.se.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Video-Audio Media

Language

eng

PubMed ID

33046636

Citation

Sulej, Tomasz, et al. "The Earliest-known Mammaliaform Fossil From Greenland Sheds Light On Origin of Mammals." Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 43, 2020, pp. 26861-26867.
Sulej T, Krzesiński G, Tałanda M, et al. The earliest-known mammaliaform fossil from Greenland sheds light on origin of mammals. Proc Natl Acad Sci U S A. 2020;117(43):26861-26867.
Sulej, T., Krzesiński, G., Tałanda, M., Wolniewicz, A. S., Błażejowski, B., Bonde, N., Gutowski, P., Sienkiewicz, M., & Niedźwiedzki, G. (2020). The earliest-known mammaliaform fossil from Greenland sheds light on origin of mammals. Proceedings of the National Academy of Sciences of the United States of America, 117(43), 26861-26867. https://doi.org/10.1073/pnas.2012437117
Sulej T, et al. The Earliest-known Mammaliaform Fossil From Greenland Sheds Light On Origin of Mammals. Proc Natl Acad Sci U S A. 2020 10 27;117(43):26861-26867. PubMed PMID: 33046636.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The earliest-known mammaliaform fossil from Greenland sheds light on origin of mammals. AU - Sulej,Tomasz, AU - Krzesiński,Grzegorz, AU - Tałanda,Mateusz, AU - Wolniewicz,Andrzej S, AU - Błażejowski,Błażej, AU - Bonde,Niels, AU - Gutowski,Piotr, AU - Sienkiewicz,Maksymilian, AU - Niedźwiedzki,Grzegorz, Y1 - 2020/10/12/ PY - 2020/10/14/pubmed PY - 2020/12/18/medline PY - 2020/10/13/entrez KW - Greenland KW - Late Triassic KW - complex occlusion KW - mammaliaform KW - multirooted tooth SP - 26861 EP - 26867 JF - Proceedings of the National Academy of Sciences of the United States of America JO - Proc Natl Acad Sci U S A VL - 117 IS - 43 N2 - Synapsids are unique in having developed multirooted teeth and complex occlusions. These innovations evolved in at least two lineages of mammaliamorphs (Tritylodontidae and Mammaliaformes). Triassic fossils demonstrate that close to the origins of mammals, mammaliaform precursors were "experimenting" with tooth structure and function, resulting in novel patterns of occlusion. One of the most surprising examples of such adaptations is present in the haramiyidan clade, which differed from contemporary mammaliaforms in having two rows of cusps on molariform crowns adapted to omnivorous/herbivorous feeding. However, the origin of the multicusped tooth pattern present in haramiyidans has remained enigmatic. Here we describe the earliest-known mandibular fossil of a mammaliaform with double molariform roots and a crown with two rows of cusps from the Late Triassic of Greenland. The crown morphology is intermediate between that of morganucodontans and haramiyidans and suggests the derivation of the multicusped molariforms of haramiyidans from the triconodont molar pattern seen in morganucodontids. Although it is remarkably well documented in the fossil record, the significance of tooth root division in mammaliaforms remains enigmatic. The results of our biomechanical analyses (finite element analysis [FEA]) indicate that teeth with two roots can better withstand stronger mechanical stresses like those resulting from tooth occlusion, than teeth with a single root. SN - 1091-6490 UR - https://www.unboundmedicine.com/medline/citation/33046636/The_earliest_known_mammaliaform_fossil_from_Greenland_sheds_light_on_origin_of_mammals_ L2 - http://www.pnas.org/cgi/pmidlookup?view=long&pmid=33046636 DB - PRIME DP - Unbound Medicine ER -