A new titanosauriform sauropod (Dinosauria: Saurischia) from the Lower Cretaceous of Hyogo, Japan.
A new titanosauriform sauropod (Dinosauria: Saurischia) from the Lower Cretaceous of Hyogo, Japan.
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DOI：
10.11646/zootaxa.3848.1.1
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发表时间：
2014-08
期刊：
影响因子：
0.9
通讯作者：
H. Saegusa;T. Ikeda
中科院分区：
文献类型：
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作者：
H. Saegusa;T. Ikeda
根据在日本西南部兵库县早白垩世筱山群中发现的部分骨骼化石，建立了一个新的属和种。本文将该新分类群命名为Tambatitanis amicitiae gen.et sp.nov.，其通过尾椎、人字形和头盖骨的以下特征来诊断：前尾椎的后关节突和神经棘的顶点位于椎体后缘之外，前尾椎的棘向前强烈弯曲，在侧视图上呈弓形，神经棘的顶点被扩大并呈半球形，其前面被深而窄的SPRF的后背侧延伸部挖开，前尾椎的横突短且呈L形，前人字形在蜥脚类动物中与体型比例最长，前人字形的末端呈杆状，中人字形的远端横向较薄，前后较长，无颅突，形成颞后窗腹面缘的枕旁突干的背侧缘在后视图中呈V形，内外短。系统发育分析表明，T. amicitiae是一个基部的泰坦龙形，可能属于东亚特有的分支Euhelopodidae。的尾部和人字形的详细描述，以记录高度的新分类群的自形特征，以及潜在的遗传信息的字符。T. amicitiae的研究结果表明，东亚基底泰坦龙型不仅在分类群的数量上，而且在尾部成分的形态变化上都是多样的。
A new genus and species of titanosauriform sauropod is erected based on a partial skeleton found in the Lower Cretaceous Sasayama Group of Hyogo Prefecture, SW Japan. The new taxon is here named as Tambatitanis amicitiae gen. et sp. nov., which is diagnosed by the following features of the caudal vertebrae, chevrons and braincase: the postzygapophysis and the summit of the neural spine of the anterior caudal vertebrae are located beyond the posterior border of the centrum, the spine of the anterior caudal vertebrae is curved strongly anteriorly and bow-shaped in lateral view, the summit of the neural spine is expanded and hemispherical with its anterior face excavated by the posterodorsal extension of a deep and narrow SPRF, the transverse process of the anterior caudal vertebrae are short and L shaped, the anterior chevron is the longest among sauropods in proportion to body size, the distal ends of the anterior chevrons are rod-shaped, the distal ends of the mid chevrons are transversely thin and anteroposteriorly long without cranial processes, and the dorsal border of the shaft of the paroccipital process that forms the ventral margin of the posttemporal fenestra is short mediolaterally and V-shaped in posterior view. A phylogenetic analysis suggests that T. amicitiae is a basal titanosauriform, possibly belonging to the East Asian endemic clade Euhelopodidae. The caudals and chevrons are described in detail in order to document highly autapomorphic features of the new taxon as well as potentially phylogenetically informative characters. The discovery of T. amicitiae suggests that East Asian basal titanosauriforms were diverse not only in the number of the taxa but also in the morphological variation of the caudal elements.