Jurassic shuotheriids show earliest dental diversification of mammaliaforms.

Autor: Mao F; Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China. maofangyuan@ivpp.ac.cn.; Division of Paleontology, American Museum of Natural History, New York, NY, USA. maofangyuan@ivpp.ac.cn., Li Z; Inner Mongolia Museum of Natural History, Hohhot, China., Wang Z; Inner Mongolia Museum of Natural History, Hohhot, China., Zhang C; Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China., Rich T; Museums Victoria, Melbourne, Victoria, Australia.; School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, Australia., Vickers-Rich P; 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., Meng J; Division of Paleontology, American Museum of Natural History, New York, NY, USA. jmeng@amnh.org.; Earth and Environmental Sciences, City University of New York, New York, NY, USA. jmeng@amnh.org.
Jazyk: angličtina
Zdroj: Nature [Nature] 2024 Apr; Vol. 628 (8008), pp. 569-575. Date of Electronic Publication: 2024 Apr 03.
DOI: 10.1038/s41586-024-07258-7
Abstrakt: 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 trigonid 1-4 . The origin of the pseudotribosphenic teeth remains unclear, obscuring our perception of shuotheriid affinities and the early evolution of mammaliaforms 1,5-9 . 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 view 1,2,6,10,11 , 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 mammaliaforms 6,12 . 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 stage 9 , 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.
(© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)
Databáze: MEDLINE
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