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1 May 2016 The First Amphisbaenians from Texas, with Notes on Other Squamates from the Middle Eocene Purple Bench Locality
Michelle R. Stocker, E. Christopher Kirk
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The shift to a cooler and drier climate through the Paleogene has been interpreted as the driver for changes in diversity and biogeographic distributions among mammalian taxa during the Eocene, leading to hypotheses of continued tropical climatic refugia in West Texas through the middle and late Eocene. However, the presence of ectothermic reptiles during that time has not been documented in detail and would potentially provide additional climatic indicators. We provide the first description of the herpetofauna from the Devil's Graveyard Formation (DGF), West Texas, the southernmost, wellsampled middle Eocene basin in North America. Specimens are derived from beds correlated with the Ui3 biochron of the late Uintan North American Land Mammal ‘Age’ (~45–40 Ma). We report the first amphisbaenians known from Texas, expanding our spatial and climatic understanding of rhineurid distribution, as well as the first glyptosaurine anguimorphs and alethinophidian snakes from the Purple Bench assemblage. These new amphisbaenians preserve a jugal posteriorly enclosing the orbit and an extremely short retroarticular process and are recovered in a clade comprising †Spathorhynchus, †Dyticonastis, †Ototriton, and †Hyporhina. The documentation of the amphisbaenians and other squamates provides biogeographic range extensions of these taxa to West Texas. Despite suggestions that West Texas was a middle and late Eocene climatic refugium for mammals adapted to subtropical forested environments, rhineurid amphisbaenians show a wide range of temperature tolerances up to the beginning of the Neogene.

© by the Society of Vertebrate Paleontology
Michelle R. Stocker and E. Christopher Kirk "The First Amphisbaenians from Texas, with Notes on Other Squamates from the Middle Eocene Purple Bench Locality," Journal of Vertebrate Paleontology 36(3), (1 May 2016).
Received: 7 March 2015; Accepted: 1 August 2015; Published: 1 May 2016
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