A new stereospondyl from the German Middle Triassic, and the origin of the Metoposauridae
A new stereospondyl from the German Middle Triassic, and the origin of the Metoposauridae
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德国中三叠世的新立体椎基和变龙科的起源
DOI：
10.1111/j.1096-3642.2007.00363.x
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发表时间：
2008
影响因子：
2.8
通讯作者：
R. Schoch
中科院分区：
文献类型：
--
作者：
R. Schoch
最近在德国南部发现的保存完好的下Keuper（拉丁阶，中三叠世）temnospondyl骨骼被分配到一个新的属和种，Callistomordax kugleri。这个分类群的特徴如下：（1）宽的不成对的前额;（2）犁骨的尖牙极大地扩大到占据整个分子的宽度;（3）中间延长和巨大，前面是凸的;（4）肱骨半月，有扩大的三角胸嵴;（5）锁骨强烈弯曲和弓形;（6）躯干极度延长到头骨长度的三倍。Callistomordax与Metoposauridae共享的模式，后颅板和吻的比例，泪腺的位置，颅底区域的形态，以及锁骨和锁骨间的结构。系统发育分析表明，Callistomordax是Metoposauridae的姐妹分类群，嵌套在由各种孔龙类分类群形成的等级内。在这个组合中，Lyrocephaliscus与Almasaurus、Callistomordax和Metoposauridae形成的一个分支是姐妹分类群。在分支分析的所有变种中，Calistomordax和Metoposauridae形成直接姐妹群。根据目前的研究结果，无论是斜龙科还是短脚龙科和rhytidosteids都与这个“孔龙类”单门动物密切相关，尽管这些分类群共享一系列的同源性。
Recent finds of well-preserved temnospondyl skeletons from the Lower Keuper (Ladinian, Middle Triassic) in southern Germany are assigned to a new genus and species, Callistomordax kugleri. This taxon is characterized by the following autapomorphies: (1) wide unpaired frontal; (2) vomerine fangs greatly enlarged to occupy entire width of element; (3) intercentra elongated and massive, anterior face being convex; (4) humerus semilunar with enlarged deltopectoral crest; (5) cleithrum strongly curved and bow-shaped; (6) trunk extremely elongated to reach three times the length of the skull. Callistomordax shares with the Metoposauridae the pattern of dermal ornamentation, the proportion of both posterior skull table and snout, the position of the lacrimal, the morphology of the basicranial region, and the structure of the clavicle and interclavicle. Phylogenetic analysis suggests Callistomordax to be the sister taxon of the Metoposauridae, nested within a grade formed by various trematosaurian taxa. In this assemblage, Lyrocephaliscus and a clade formed by Almasaurus, Rileymillerus, Callistomordax, and the Metoposauridae are sister taxa. In all variants of the cladistic analysis, Callistomordax and the Metoposauridae form immediate sister groups. According to the present findings, neither plagiosaurids nor brachyopoids and rhytidosteids are closely related to this ‘trematosaurian’ monophylum, although these taxa share a range of homoplasies. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 152, 79–113.