| 中国晚侏罗世多瘤齿兽类哺乳动物的发现及其意义 |
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| 关键词:multituberculates Late Mesozoic Liaoning China |
| 基金项目:中国科学技术部973项目(编号: 2012CB822004);中国地质调查局地质矿产调查评价专项(编号: 1212011120105) |
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| The Discovery of A Late Jurassic Multituberculate (Mammalia: Allotheria) from China and Its Significance |
| 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 been puzzled about the evolutionary origins of multituberculates. Recently, a new fossil mammal was unearthed from beds of 160 million years in Jianchang County of Liaoning Province. 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 new mammal is named Rugosodon eurasiaticus 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. The closest relative of Rugosodon is from the Jurassic beds of Western Europe, so the new species was named Rugosodon eurasiaticus because this fossil and its mammalian family have provided the newest evidence that mammalian faunas of Europe and Asia were very similar during the Late Jurassic. Its ankle bones are surprisingly mobile and flexible, suggesting that Rugosodon eurasiaticus was a fast-running and agile mammal. Also very important is that Rugosodon eurasiaticus is the earliest-known skeletal fossil of multituberculates, by studying it paleontologists can trace the evolutionary origins of the versatile and diverse locomotor adaptations of the later multituberculates that would include tree climbers, ground runners, so as to dig mammals that lived underground. Rugosodon eurasiaticus is an nocturnal mammal (see the life reconstruction) and lived in a temperate climate on lakeshores in what is now northeastern China, and it shared the land with the feathered dinosaur Anchiornis, the pterosaur Darwinipterus, and abundant arthropods, as well as several other mammals. |
| JI Yan-nan,WANG Xu-ri,YUAN Chong-xi,JI Qiang.2014.The Discovery of A Late Jurassic Multituberculate (Mammalia: Allotheria) from China and Its Significance[J].Acta Geoscientica Sinica,35(3):277-283. |
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