Largest known Mesozoic multituberculate from Eurasia and implications for multituberculate evolution and biology.
A new multituberculate, Yubaartar zhongyuanensis gen. and sp. nov., is reported from the Upper Cretaceous of Luanchuan County, Henan Province, China. The holotype of the new taxon is a partial skeleton with nearly complete cranium and associated lower jaws with in situ dentitions. The new species is the southern-most record of a Late Cretaceous multituberculate from outside of the Mongolian Plateau in Asia and represents the largest known Mesozoic multituberculate from Eurasia. The new specimen displays some intriguing features previously unknown in multituberculates, such as the first evidence of replacement of the ultimate upper premolar and a unique paleopathological case in Mesozoic mammals in which the animal with a severely broken right tibia could heal and survive in natural condition. The phylogenetic analysis based on craniodental characters places Yubaartar as the immediate outgroup of Taeniolabidoidea, a group consisting of a North American clade and an Asian clade. This relationship indicates at least a faunal interchange of multituberculates before the K-Pg transition. The new evidence further supports the hypothesis that disparity in dental complexity, which relates to animal diets, increased with generic richness and disparity in body size, and that an adaptive shift towards increased herbivory across the K-Pg transitional interval.
Henan Geological Museum, Zhengzhou, Henan 450016, China.
Li
L
Xu
Henan Geological Museum, Zhengzhou, Henan 450016, China.
Xingliao
X
Zhang
Henan Geological Museum, Zhengzhou, Henan 450016, China.
Hanyong
H
Pu
Henan Geological Museum, Zhengzhou, Henan 450016, China.
Songhai
S
Jia
Henan Geological Museum, Zhengzhou, Henan 450016, China.
Jiming
J
Zhang
Institute of Geology, Chinese Academy of Geological Sciences, Beijing 10037, China.
Junchang
J
Lü
Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024, USA.
Jin
J
Meng
D000818:Animals; D001208:Asia; D005075:Biological Evolution; D005060:Europe; D005580:Fossils; D005844:Geology; D008322:Mammals / Q000145:classification*; D010163:Paleontology