中国辽宁首次发现侏罗纪多瘤齿兽类哺乳动物

发布时间:2013年08月16日 20:35 | 进入复兴论坛 | 来源：中国网络电视台 | 手机看新闻

原标题：

Discovery of A New Jurassic Multituberculate mammal

from Western Liaoning, China

An international team of scientists from Chinese Academy of Geological Sciences (Beijing), Beijing Museum of Natural History and the University of Chicago discovered a new fossil mammal from beds of 160 million years in the Jianchang County of Liaoning Province of China. This fossil helps to shed the light on the earliest evolution of multituberculates, a major group of extinct mammals that lived in the Mesozoic times of dinosaurs and ultimately survived the mass extinction that wiped out dinosaurs 65 million years ago. The research result is reported in Science magazine on August 16, 2013.

Multituberculate mammals are characterized by numerous tubercles (tiny bumps, or cusps) on their back teeth for chewing on plants. Overall their incisor and molar teeth are similar to those of rodents, but multituberculates evolved long before rodents of the Cenozoic Era.

Multituberculates are either omnivores that could feed on almost anything and everything, or efficient plant eaters that are successful in exploiting herbivorous niches not accessible to other vertebrates. Thanks to their versatile feeding and locomotor adaptations, multituberculates became the most abundant mammals of the Mesozoic Era and constitute almost half of all mammal species that lived in the Jurassic and Cretaceous. Their lineage has the distinction as the most long-lived lineage in the mammalian history, starting from 170 million years ago, and went extinct around 35 million years.

However, because multituberculates have many unique and highly specialized tooth and skull features, paleontologists have long puzzled about the evolutionary origins of multituberculates.

The new mammal is called Rugosodon after the rugose teeth ornamented by numerous tiny ridges and grooves and pits, indicating that it was an omnivore that fed on leaves and seeds of ferns and gymnosperm plants, plus worms and insects. Its ankle bones are surprisingly mobile and flexible, suggesting that Rugosodon was a fast-running and agile mammal. Also very important is that Rugosodon is the earliest-known skeletal fossil of multituberculates, by studying it paleontologists can traced the evolutionary origins of the versatile and diverse locomotor adaptations of the later multituberculates that would include tree climbers, ground runners, to digging mammals lived underground.

The closest relative of Rugosodon is from the Jurassic beds of Western Europe - so the scientists named the new species as Rugosodon eurasiaticus because this fossil and its mammalian family have provided the newest evidence that mammalian faunas of Europe and Asia are very similar during the Late Jurassic.

Rugosodon is an nocturnal mammal (see the life reconstruction) and lived in a temperate climate in on lakeshores in what is now the northeastern China, and it shared the land with the feathered dinosaur Anchiornis, the pterosaur Darwinipterus, and abundant arthropods, several other mammals.

The research was carried out by Drs. Chong-xi Yuan and Qiang Ji of Institue of Geology, CAGS, Dr. Qing-jin Meng of Beijing Museum of Natural History, Dr. Alan R. Tabrum of Carnegie Museum of Natural History, and Dr. Zhexi Luo of the University of Chicago. It was funded by Ministry of Science and technology of China (Project 973: 2012CB822004), Ministry of Land Resources of China, by Beijing Academy of Science and Technology(IG201101N), and by the National Science Foundation (US), the University of Chicago.

The type specimen was found by Dr. Qiang Ji and deposited in the fossil collections of Beijing Museum of Natural History.