Saegusa Haruo, Ikeda Tadahiro
Institute of Natural and Environmental Sciences, University of Hyogo, Hyogo 669-1546, Japan; Email:
Museum of Nature and Human Activities, Hyogo, Hyogo 669-1546, Japan; Email: unknown.
Zootaxa. 2014 Aug 12;3848:1-66. doi: 10.11646/zootaxa.3848.1.1.
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.
基于在日本西南部兵库县下白垩统笹山群发现的部分骨骼化石，建立了一个泰坦巨龙形蜥脚类恐龙的新属新种。这个新分类单元被命名为友谊坦巴泰坦（Tambatitanis amicitiae）属及新种，其依据尾椎、脉弧和脑壳的以下特征来鉴别：前尾椎的后关节突和神经棘顶端位于椎体后缘之后，前尾椎的神经棘强烈向前弯曲，在侧视图中呈弓形，神经棘顶端扩展呈半球形，其前表面被一个深而窄的SPRF的后上延伸部挖出一个凹坑，前尾椎的横突短且呈L形，前脉弧是蜥脚类恐龙中与身体大小比例最长的，前脉弧远端呈杆状，中脉弧远端横向薄且前后长，没有颅突，构成颞后窗腹缘的枕髁突轴的背缘在侧视图中短且呈V形。系统发育分析表明，友谊坦巴泰坦是一种基础泰坦巨龙形恐龙，可能属于东亚特有的类群——马门溪龙科。详细描述了尾椎和脉弧，以记录新分类单元高度自近裔性状以及潜在的系统发育信息特征。友谊坦巴泰坦的发现表明，东亚基础泰坦巨龙形恐龙不仅在分类单元数量上多样，而且在尾椎元素的形态变异上也多样。
