Squamate phylogeny and evolution: fossil marine lizards, snakes, and basal terrestrial lizards

肢体蜥蜴的蛇起源和进化是脊椎动物进化生物学中一个经久不衰的谜。随着新的证据重新引发了关于蛇起源的争议，这一话题目前重新引起了人们的兴趣。有两种截然不同的假说：1)蛇与水生肢体蜥蜴有共同的祖先；2)蛇与穴居的陆栖无肢蜥蜴有共同的祖先。新数据的收集和分析将集中在被广泛认为非常原始的现代盲穴蛇(头骨蛇)上。还将收集和描述来自南美洲、澳大利亚、非洲和中东的白垩纪时代蛇化石的新数据。有关蜥蜴的新数据将通过研究鲜为人知的白垩纪海洋化石物种(即斑尾龙、石斑龙和圆锥龙)以及通过研究现代无肢洞穴蜥蜴(称为双肢蜥蜴和双肢蜥蜴)来获得。进化关系或系统发育的模式将通过构建称为分支图的分支图来产生，该分支图源于对解剖数据(骨骼、肌肉等)的分析。这项对化石和活着的蛇和蜥蜴进化关系的研究将阐明产生这些动物迷人的解剖学特征(例如，肢体到鳍，巨人)的进化模式和过程，并进一步测试蛇的水生和洞穴起源。收集和研究新的化石不断修正我们对过去及其生物多样性的理解，并提供对现代世界如何组织的洞察。研究活着的蛇和蜥蜴的解剖学中未被描述的方面，特别是穴居的脊椎蛇，将有助于确定哪些活着的动物仍然具有与它们的原始或早期祖先最相似的特征。总的来说，这些新数据将通过修改现有的进化树，或通过为新的假设提供额外的支持，来完善系统发生学。关于蛇和蜥蜴进化的新数据和新想法将对关于这些动物起源的激动人心的辩论做出重大贡献。

The origin and evolution of snakes from limbed lizards is an enduring enigma of vertebrate evolutionary biology. The topic is currently enjoying a revival of interest as new evidence has renewed controversy on the origins of snakes. There are two contrasting hypotheses: 1) snakes share a common ancestor with aquatic limbed lizards; 2) snakes share a common ancestor with burrowing, terrestrial, limbless lizards. Collection and analysis of new data will focus on modern blind burrowing snakes (scolecophidians), widely thought to be very primitive. New data will also be collected and described for Cretaceous-aged fossil snakes from South America, Australia, Africa, and the Middle East. New data from lizards will be obtained by studying poorly known Cretaceous fossil marine species (i.e., aigialosaurs, dolichosaurs, and coniasaurs), and by studying modern limbless, burrowing lizards, known as dibamids and amphisbaenids. Patterns of evolutionary relationship, or phylogenies, will be produced by constructing branching diagrams called cladograms derived from analysis of anatomical data (bones, muscles, etc.). This study of the evolutionary relationships of fossil and living snakes and lizards will illuminate the evolutionary patterns and processes that produced the fascinating anatomical features of these animals (e.g., limblessness, limbs to fins, gigantism), and to further test the aquatic vs. burrowing origins of snakes. Collecting and studying new fossils continually revises our understanding of the past and its biodiversity, and provides insights into how the modern world is organized. Studying undescribed aspects of the anatomy of living snakes and lizards, in particular burrowing scolecophidian snakes, will help to determine what groups of living animals still share most features in common with their primitive, or early, ancestors. Collectively, these new data will refine phylogenies by either modifying existing evolutionary trees, or by providing additional support for new hypotheses. New data and new ideas on the evolution of snakes and lizards will be significant contributions to the exciting debate on the origins of these animals.