论文标题：A tiny new Middle Triassic stem-lepidosauromorph from Germany: implications for the early evolution of lepidosauromorphs and the Vellberg fauna

期刊：Scientific Reports

作者：Gabriela Sobral and Tiago R. Simões et al.

发表时间：2020/02/20

DOI：10.1038/s41598-020-58883-x

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《科学报告》本周发表一篇论文 A tiny new Middle Triassic stem-lepidosauromorph from Germany: implications for the early evolution of lepidosauromorphs and the Vellberg fauna 介绍了德国发现的一个史前爬行动物新种。这一物种名为Vellbergia bartholomaei，其解剖学特征将增进我们对鳞龙型类早期演化的理解。

Vellbergia bartholomaei 正模标本的图片（a）和对应的线条图（b）。比例尺大约为5毫米。来源：Sobral, G., Simões, T.R. & Schoch, R.R.

鳞龙形下纲是最大、多样性最丰富的四足动物谱系之一，有超过1.05万个物种。作为现代蜥蜴、蛇和爬行动物楔齿蜥属的祖先，鳞龙形下纲的样本只在一些三叠纪遗址发现过，而对它们早期演化的大部分认知尚处于空白。

Gabriela Sobral和同事在德国费尔贝格（Vellberg）的中三叠纪（2.47亿-2.37亿年历史）沉积中发现了这个小化石。分析显示，该化石样本是一种此前未知的早期鳞龙形下纲物种。作为费尔贝格遗址挖掘到的最小样本之一，它可能是该处采集到的第一个幼年动物化石。V. bartholomaei与鳞龙形下纲的其它种不同，它独有的特征包括相对下颌来说又窄又薄又短的牙齿；但它具有现代蜥蜴和楔齿蜥祖先的一系列特征。研究发现，Vellbergia可能是这两个谱系的共同祖先，增进了我们对早期爬行动物演化的认识。

除了这个化石，其它证据也显示费尔贝格是理解早期鳞龙形下纲演化的重要遗址。由于早三叠纪的化石记录非常有限，中三叠纪的样本具有根本性的重要意义，不仅可以理解脊椎动物如何从二叠-三叠纪大灭绝（约2.52亿年前）中恢复，还能理解它们是如何分化成现代物种的。

摘要：

The Middle Triassic was a time of major changes in tetrapod faunas worldwide, but the fossil record for this interval is largely obscure for terrestrial faunas. This poses a severe limitation to our understanding on the earliest stages of diversification of lineages representing some of the most diverse faunas in the world today, such as lepidosauromorphs (e.g., lizards and tuataras). Here, we report a tiny new lepidosauromorph from the Middle Triassic from Vellberg (Germany), which combines a mosaic of features from both early evolving squamates and rhynchocephalians, such as the simultaneous occurrence of a splenial bone and partial development of acrodonty. Phylogenetic analyses applying different optimality criteria, and combined morphological and molecular data, consistently recover the new taxon as a stem-lepidosauromorph, implying stem-lepidosauromorph species coinhabited areas comprising today’s central Europe at the same time as the earliest known rhynchocephalians and squamates. It further demonstrates a more complex evolutionary scenario for dental evolution in early lepidosauromorphs, with independent acquisitions of acrodonty early in their evolutionary history. The small size of most terrestrial vertebrates from Vellberg is conspicuous, contrasting to younger Triassic deposits worldwide, but comparable to Early Triassic faunas, suggesting a potential long-lasting Lilliput effect in this fauna.

（来源：科学网）