A NEW SPECIES OF BAENID TURTLE FROM THE KAIPAROWITS FORMATION (UPPER CRETACEOUS, CAMPANIAN) OF SOUTHERN UTAH
A NEW SPECIES OF BAENID TURTLE FROM THE KAIPAROWITS FORMATION (UPPER CRETACEOUS, CAMPANIAN) OF SOUTHERN UTAH
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DOI：
10.1080/02724634.2015.1009084
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发表时间：
2015-11-02
影响因子：
1.4
通讯作者：
Lively, Joshua R.
中科院分区：
文献类型：
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作者：
Lively, Joshua R.
本文描述了新发现的产于犹他州南部坎帕尼亚阶Kaiparowits组中的斑龟标本，命名为Arvinachelys goldeni，gen. et sp. nov.使用微型计算机断层扫描（CT）对头骨进行扫描，以更好地了解其内部解剖结构。这baenid具有两个不同的外鼻孔几乎完全分开的背侧投影的前颌骨和腹侧延伸的鼻骨，一个autapomorphic功能之间已知baenid类群。头骨呈楔形，喙部宽，鼻侧部扩张。头骨/贝壳组合的重要性以Arvinachelys goldeni为例，因为属于这个分类单元的孤立贝壳以前被分配到Plesiobaena属，而更完整的材料的系统发育分析支持与马斯特里赫特分类单元Hayemys latifrons的姐妹关系。这些分类群在Baenodda中相对基础，Baenodda是Baenidae中的一个嵌套分支。一般的壳形态表现出的Plesiobaena antiqua，Peckemys brinkman和Palatobaena cohen先前被假设为支持一个单系分支，包括这三个类群，沿着Cedrobaena putorius，Gamerabaena sonsalla，Palatobaena bairdi和Palatobaena gaffneyi。然而，包括Arvinachelys goldeni，gen. et sp. nov.，在Baenidae的系统发育分析中，这些分类群所表现出的特征状态代表了Baenodda中的近形状态，该分支内的系统发育关系需要重新评估。
Newly discovered baenid turtle specimens from the middle Campanian Kaiparowits Formation of southern Utah are described herein as a new taxon, Arvinachelys goldeni, gen. et sp. nov. The holotype consists of a nearly complete articulated skeleton and shell. The skull was scanned using micro-computed tomography (CT) to gain a better understanding of its internal anatomy. This baenid possesses two distinct external nares almost completely separated by a dorsal projection of the premaxillae and a ventral extension of the nasals, an autapomorphic feature among known baenid taxa. The skull is wedge-shaped with a broad rostrum and laterally expanded nasals. The importance of skull/shell associations is exemplified by Arvinachelys goldeni, because isolated shells attributable to this taxon had previously been assigned to the genus Plesiobaena, whereas phylogenetic analysis of more complete material supports a sister relationship with the Maastrichtian taxon Hayemys latifrons. These taxa are relatively basal within the Baenodda, a nested clade within Baenidae. The general shell morphology exhibited by Plesiobaena antiqua, Peckemys brinkman, and Palatobaena cohen was previously hypothesized to support a monophyletic clade that included those three taxa, along with Cedrobaena putorius, Gamerabaena sonsalla, Palatobaena bairdi, and Palatobaena gaffneyi. However, the inclusion of Arvinachelys goldeni, gen. et sp. nov., in a phylogenetic analysis of Baenidae indicates that the character states exhibited by those taxa are representative of plesiomorphic states within Baenodda, and the phylogenetic relationships within this clade are in need of reevaluation.