Reigitherium (Meridiolestida, Mesungulatoidea) an Enigmatic Late Cretaceous Mammal from Patagonia, Argentina: Morphology, Affinities, and Dental Evolution
Reigitherium (Meridiolestida, Mesungulatoidea) an Enigmatic Late Cretaceous Mammal from Patagonia, Argentina: Morphology, Affinities, and Dental Evolution
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DOI：
10.1007/s10914-018-9437-x
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发表时间：
2019-12-01
影响因子：
1.9
通讯作者：
Rougier, Guillermo W.
中科院分区：
文献类型：
--
作者：
Harper, Tony;Parras, Ana;Rougier, Guillermo W.
在巴塔哥尼亚中部的上白垩统拉科洛尼亚组中收集到的新的牙齿和牙齿化石为神秘的哺乳动物Reigitherium的形态、摄食生态和关系提供了新的证据。这里描述的新发现的标本包括上牙列和几个部分牙齿的元素，阐明了序列同源性和后犬齿牙式（四个前臼齿和三个臼齿）的基本问题。这一新的证据支持了Reigitherium在高级的马陆分支Mesungulatoidea中的嵌套位置。上、下臼齿形元素的表型特征包括在初级三角形和三角形内限定的强烈的釉质细锯齿，升高的cingulids，以及尖端/cuspulids的新形态外观，所有这些都增加了整体冠的复杂性。牙齿地形分析比较Reigitherium和它的姐妹分类群Peligrotherium白垩纪和新生代兽类之间的mesungulatoids和南美有袋类动物类群，接替他们在小到中型草食动物生态位在古新世的功能相似性。以前的分类属性Reigitherium进行了讨论，并与其他的Reigitheridans的比较突出了显着的辐射，这组在白垩纪的南美洲。
New dental and dentary fossils collected in the Upper Cretaceous La Colonia Formation in central Patagonia provide new evidence on the morphology, feeding ecology, and relationships of the enigmatic mammal Reigitherium. The newly discovered specimens described here include elements of the upper dentition and several partial dentaries, elucidating fundamental questions of serial homology and postcanine dental formula (four premolars and three molars). This new evidence supports a nested position of Reigitherium within the advanced meridiolestidan clade Mesungulatoidea. Apomorphic features of the upper and lower molariform elements include intense enamel crenulation circumscribed within the primary trigon and trigonid, elevated cingulids, and the neomorphic appearance of cusps/cuspulids, all of which increase overall crown complexity. A Dental Topography Analysis comparing Reigitherium and its sister taxon Peligrotherium to Cretaceous and Cenozoic therians demonstrates functional similarity between the mesungulatoids and South American marsupial taxa that succeed them in the small-to medium-sized herbivore niche during the Paleocene. Previous taxonomic attributions of Reigitherium are discussed and comparisons with other meridiolestidans highlight the remarkable radiation of this group in the Cretaceous of South America.