An early bothremydid (Testudines, Pleurodira) from the Late Cretaceous (Cenomanian) of Utah, North America
An early bothremydid (Testudines, Pleurodira) from the Late Cretaceous (Cenomanian) of Utah, North America
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DOI：
10.7717/peerj.2502
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发表时间：
2016-09-28
期刊：
影响因子：
2.7
通讯作者：
Kirkland, James I.
中科院分区：
文献类型：
--
作者：
Joyce, Walter G.;Lyson, Tyler R.;Kirkland, James I.
背景。Bothremydidae是一个已经灭绝的白垩纪至古近纪的白垩纪至古近纪，生活在非洲、欧洲、印度、马达加斯加和南北美洲的绝种白垩纪龟。在非洲的晚白垩纪至古近纪，这一群体最为多样化。然而，人们对这一群体的早期进化知之甚少。我们在这里描绘了一只海龟化石，它来自于美国犹他州西南部雪松峡谷麦克法兰矿的晚白垩世早期沉积物。利用与新龟有关的沉积物推断其地层来源和沉积环境。将该化石与先前描述的化石胸鳍类进行比较，将其整合到改进的pelomedusoid龟的系统发育分析中，并重新评估了botherremydid龟的生物地理学。根据新的系统发育假说，六个先前建立的分类单元名称被转换为系统发育定义的分支名称，以帮助交流。新发现的龟化石可以确信地推断为起源于晚Cenomanian Culver煤带Naturita组的微咸水相。该化石可与所有其他先前描述的胸骨兽区分，因此被指定为一个新的分类单元，Paiutemys tibert gen. et. sp. 11 .系统发育分析将该新分类单元与欧洲Polysternon provinciale， Foxemys trabanti和Foxemys mechinorum在Bothremydinae的底部。生物地理分析表明，双足龟起源于冈瓦纳的陆生龟，但双足龟适应了近岸的海洋环境，因此应该被视为具有环大西洋分布。
Background. Bothremydidae is a clade of extinct pleurodiran turtles known from the Cretaceous to Paleogene of Africa, Europe, India, Madagascar, and North and South America. The group is most diverse during the Late Cretaceous to Paleogene of Africa. Little is known, however, about the early evolution of the group.Methods. We here figure and describe a fossil turtle from early Late Cretaceous deposits exposed at MacFarlane Mine in Cedar Canyon, southwestern Utah, USA. The sediments associated with the new turtle are utilized to infer its stratigraphic provenience and the depositional settings in which it was deposited. The fossil is compared to previously described fossil pleurodires, integrated into a modified phylogenetic analysis of pelomedusoid turtles, and the biogeography of bothremydid turtles is reassessed. In light of the novel phylogenetic hypotheses, six previously established taxon names are converted to phylogenetically defined clade names to aid communication.Results. The new fossil turtle can be inferred with confidence to have originated from a brackish water facies within the late Cenomanian Culver Coal Zone of the Naturita Formation. The fossil can be distinguished from all other previously described pleurodires and is therefore designated as a new taxon, Paiutemys tibert gen. et. sp. nov. Phylogenetic analysis places the new taxon as sister to the European Polysternon provinciale, Foxemys trabanti and Foxemys mechinorum at the base of Bothremydinae. Biogeographic analysis suggests that bothremydids originated as continental turtles in Gondwana, but that bothremydines adapted to near-shore marine conditions and therefore should be seen as having a circum-Atlantic distribution.