Combined data analysis of fossil and living mammals: a Paleogene sister taxon of Placentalia and the antiquity of Marsupialia
Combined data analysis of fossil and living mammals: a Paleogene sister taxon of Placentalia and the antiquity of Marsupialia
复制标题
化石和现存哺乳动物的综合数据分析：胎盘目的古近纪姐妹分类单元和有袋目的古代
DOI：
10.1111/cla.12499
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发表时间：
2022
期刊：
影响因子：
3.6
通讯作者：
M. Novacek
中科院分区：
文献类型：
--
作者：
P. Velazco;A. Buczek;Eva A. Hoffman;Devin K. Hoffman;M. O'Leary;M. Novacek
白垩纪-古近纪(KPG)界线是地球五大灭绝事件之一，发生在化石记录中Placentalia出现之前。戈壁沙漠、蒙古和北美西部内陆有重要的哺乳动物化石，它们正好出现在KPG边界之前和之后(例如Prodiacdon，Deltatheridium)，这些化石还有待于在特征丰富的背景下利用分子数据进行系统发育测试。我们在这里提出了系统发育分析>；6000新评分的解剖学观察来自六个未经测试的化石，并添加到最大的哺乳动物现有的形态矩阵。这些数据与27个核基因的序列数据相结合。结果表明，存在一个新的真兽类姐妹支系Placentalia，我们命名并描述了它的特征。已灭绝的Leptictidae分支是这个胎盘姐妹分支的一部分，表明该姐妹分支在KPG事件中幸存下来，并在古近纪胎盘辐射期间共存于古代生态系统中。在这种特征丰富的背景下分析白垩纪变态生物Deltatherdium表明它是有袋类的一员，这一发现将有袋类的最小年龄延长到了KPG界线之前。许多来自多个解剖系统的共享特征支持将Deltatheridium归入袋纲。精致的新标本的计算机断层扫描更好地记录了Deltatheridium的有袋类牙齿替换模式。新的胎盘姐妹支系既有亚洲物种，也有北美物种，其祖先特征是具有共同的衍生特征，如后肢经过修改以适应跳跃运动。
The Cretaceous–Paleogene (KPg) boundary, one of Earth’s five major extinction events, occurred just before the appearance of Placentalia in the fossil record. The Gobi Desert, Mongolia and the Western Interior of North America have important fossil mammals occurring just before and after the KPg boundary (e.g. Prodiacodon, Deltatheridium) that have yet to be phylogenetically tested in a character‐rich context with molecular data. We present here phylogenetic analyses of >6000 newly scored anatomical observations drawn from six untested fossils and added to the largest existing morphological matrix for mammals. These data are combined with sequence data from 27 nuclear genes. Results show the existence of a new eutherian sister clade to Placentalia, which we name and characterize. The extinct clade Leptictidae is part of this placental sister clade, indicating that the sister clade survived the KPg event to co‐exist in ancient ecosystems during the Paleogene radiation of placentals. Analysing the Cretaceous metatherian Deltatheridium in this character‐rich context reveals it is a member of Marsupialia, a finding that extends the minimum age of Marsupialia before the KPg boundary. Numerous shared‐derived features from multiple anatomical systems support the assignment of Deltatheridium to Marsupialia. Computed tomography scans of exquisite new specimens better document the marsupial‐like dental replacement pattern of Deltatheridium. The new placental sister clade has both Asian and North American species, and is ancestrally characterized by shared derived features such as a hind limb modified for saltatorial locomotion.