Discovery of the oldest South American fossil lizard illustrates the cosmopolitanism of early South American squamates

Squamates have an extremely long evolutionary history with a fossil record that extends into the Middle Triassic. However, most of our knowledge of their early evolutionary history is derived from Laurasian records. Therefore, fundamental questions regarding the early evolution of squamates in the Southern Hemisphere, such as the origins of the extremely diverse and endemic South American fauna, remain unanswered. Here, we describe a new lizard species that represents the oldest fossil squamate from South America, demonstrating that squamates were present on that continent at least 20 million years earlier than previously recorded. The new species represents the first occurrence of the extinct squamate family Paramacellodidae in South America and displays an unusual limb morphology. Finally, our findings suggest early South American squamates were part of a much broader distribution of their respective clades, in sharp contrast to the high levels of endemicity characteristic of modern faunas.


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Our data was compiled in Mesquite (v. 3.04); molecular alignments were performed with MAFFT (Multiple Sequence Alignment Software Version 7); our analysis were performed in the phylogenetic software Mr, Bayes (v. 3.2.6) and BEAST2.
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Study description
We studied the anatomy of a new lizard species from the Cretaceous of southeast Brazil and investigate its phylogentic relationships by means of parsimony and Bayesian analyses on morphological (personally collected in museum collections) and molecular (available online) data from all major lineages of diapsid reptiles.

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Other than the specimen originally described in the paper, the collected data from 131 species of extant and extinct reptiles from over 50 different museum collections across the world, spanning in geological time from 307 myr to the present.

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Our samples were obtained in a way to maximize the representation of the modern diversity of reptiles, as well as the representation of fossil lineages, focusing on the earliest and most complete fossils from each reptile clades studied here.

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Data was collected using digital photography and CT scanning technologies for the morphological data, whereas molecular data was obtained from GenBank.
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The new material described in the paper was collected in João Pinheiro, north Minas Gerais State, southeast Brazil.