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

蛇从肢蜥蜴的起源和进化是脊椎动物进化生物学的一个持久的谜。随着新的证据重新引发了关于蛇起源的争论，这个话题目前正重新引起人们的兴趣。有两种相反的假设：1）蛇与水栖有肢蜥蜴有共同的祖先; 2）蛇与穴居的陆地无肢蜥蜴有共同的祖先。新数据的收集和分析将集中在现代盲穴蛇（学名：Acuecophidians）上，这种蛇被广泛认为是非常原始的。还将收集和描述来自南美洲、澳大利亚、非洲和中东的蛇类化石的新数据。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，通过研究现代无肢穴居蜥蜴，被称为dibamids和amphisbaenids。进化关系的模式，或进化关系，将通过构建分支图（称为分支图）来产生，分支图来自解剖数据（骨骼，肌肉等）的分析。这项对化石和活蛇和蜥蜴进化关系的研究将阐明产生这些动物迷人解剖特征的进化模式和过程（例如，无肢、四肢与鳍、无肢症），并进一步测试蛇的水生起源与穴居起源。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见解。研究活着的蛇和蜥蜴的解剖学的未描述的方面，特别是穴居的蛇，将有助于确定哪些活着的动物群体仍然与它们的原始或早期祖先共享大多数共同特征。总的来说，这些新的数据将通过修改现有的进化树或为新的假设提供额外的支持来完善遗传学。关于蛇和蜥蜴进化的新数据和新想法将对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.