Eocene lizard from Germany reveals amphisbaenian origins
Eocene lizard from Germany reveals amphisbaenian origins
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来自德国的始新世蜥蜴揭示了两栖类起源
作者：
Johannes Müller;C. Hipsley;J. Head;N. Kardjilov;A. Hilger;M. Wuttke;R. Reisz
双齿蜥是一种特殊的穴居蜥蜴分支，其特征是蛇一样的身体和一个非常坚固的头骨，适合头先挖洞。两栖类的进化起源是有争议的，分子数据将它们与蜥蜴类（旧大陆陆栖蜥蜴的一个分支）联系在一起，而形态学支持与蛇和其他无肢有鳞动物的分类。关于茎型双菲斯巴人化石的报道已经被证伪，而且之前没有化石能够验证这些相互竞争的系统发育假说，也没有化石能够揭示祖先双菲斯巴人的生态。在这里，我们报告的发现一个新的蜥蜴样蜥蜴始新世梅塞尔地方的德国，提供了第一个形态学证据的基础上，lacertid-amphisbaenian单系强化，无运动的头骨屋顶和braincase，支持的观点，身体伸长和四肢的amphisbaenians和蛇独立进化。有鳞动物的体形和生态的形态测量分析表明，新分类单元的颅后解剖结构与机会主义的穴居习惯最一致，这与颅强化相结合表明，头先穴居是在身体伸长之前进化的，并且可能是关键的第一步。在两个物种的化石中。
Amphisbaenia is a speciose clade of fossorial lizards characterized by a snake-like body and a strongly reinforced skull adapted for head-first burrowing. The evolutionary origins of amphisbaenians are controversial, with molecular data uniting them with lacertids, a clade of Old World terrestrial lizards, whereas morphology supports a grouping with snakes and other limbless squamates. Reports of fossil stem amphisbaenians have been falsified, and no fossils have previously tested these competing phylogenetic hypotheses or shed light on ancestral amphisbaenian ecology. Here we report the discovery of a new lacertid-like lizard from the Eocene Messel locality of Germany that provides the first morphological evidence for lacertid–amphisbaenian monophyly on the basis of a reinforced, akinetic skull roof and braincase, supporting the view that body elongation and limblessness in amphisbaenians and snakes evolved independently. Morphometric analysis of body shape and ecology in squamates indicates that the postcranial anatomy of the new taxon is most consistent with opportunistically burrowing habits, which in combination with cranial reinforcement indicates that head-first burrowing evolved before body elongation and may have been a crucial first step in the evolution of amphisbaenian fossoriality.