Lepidosauromorphs

Lepidosauromorphs comprise one of the most successful groups of reptiles to have ever evolved, with an evolutionary history that started during the Permian, over 250million years ago. Although rhynchocephalians (tuataras) quickly radiated into multiple species distributed across various continents, the other major lineages of lepidosauromorphs—represented by squamates (lizards, snakes and amphisbaenians)—subsequently surpassed rhynchocephalians in biodiversity and morphotypes, becoming by far the dominant group of lepidosaurs on Earth today with more than 10, 000 species. Here, we highlight some of the most prominent aspects of lepidosauromorph evolution. We start by illustrating the century old challenge of understanding the taxonomic composition of lepidosauromorphs and how the major lizard families are related to each other. Subsequently, we describe the early history of some of the most diverse taxonomic lineages of lepidosauromorphs to have evolved (e.g., iguanians, geckos, snakes and amphisbaenians) and how they were distributed across space and time based on their fossil record. Further, we illustrate some of their most important anatomical features and major evolutionary patterns, including the origin of the lizard skull, different modes of tooth attachment and implantation, the multiple evolution of snake-like forms and exceptional evolutionary novelties in the shape of their skull towards hard biting and large gape feeding.