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Proc Biol Sci. 2017 Jan 25;284(1847). pii: 20161902. doi: 10.1098/rspb.2016.1902.

A new Late Cretaceous iguanomorph from North America and the origin of New World Pleurodonta (Squamata, Iguania).

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Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
Department of Anatomy, NYIT College of Osteopathic Medicine, Old Westbury, NY 11568, USA.
Department of Vertebrate Paleontology, American Museum of Natural History, New York, NY 10024, USA.
Department of Zoology and University Museum of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA.
Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA.


Iguanomorpha (stem + crown Iguania) is a diverse squamate clade with members that predominate many modern American lizard ecosystems. However, the temporal and palaeobiogeographic origins of its constituent crown clades (e.g. Pleurodonta (basilisks, iguanas, and their relatives)) are poorly constrained, mainly due to a meagre Mesozoic-age fossil record. Here, we report on two nearly complete skeletons from the Late Cretaceous (Campanian) of North America that represent a new and relatively large-bodied and possibly herbivorous iguanomorph that inhabited a semi-arid environment. The new taxon exhibits a mosaic of anatomical features traditionally used in diagnosing Iguania and non-iguanian squamates (i.e. Scleroglossa; e.g. parietal foramen at the frontoparietal suture, astragalocalcaneal notch in the tibia, respectively). Our cladistic analysis of Squamata revealed a phylogenetic link between Campanian-age North American and East Asian stem iguanomorphs (i.e. the new taxon + Temujiniidae). These results and our evaluation of the squamate fossil record suggest that crown pleurodontans were restricted to the low-latitude Neotropics prior to their early Palaeogene first appearances in the mid-latitudes of North America.


Cretaceous; Iguanomorpha; Palaeogene; Pleurodonta; palaeobiogeography; palaeoecology

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