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Shastasaurus altispinus (Ichthyosauria, Shastasauridae) from the Upper Triassic of the El Antimonio district, northwestern Sonora, Mexico

Published online by Cambridge University Press:  19 May 2016

Jack M. Callaway
Affiliation:
Department of Geological Sciences, University of Rochester, Rochester, New York 14627
Judy A. Massare
Affiliation:
Department of Geological Sciences, University of Rochester, Rochester, New York 14627

Abstract

New specimens of Shastasaurus altispinus Merriam are recognized from the Upper Triassic Antimonio Formation in the El Antimonio district of northwestern Sonora, Mexico. This represents the first occurrence of the species outside of its type locality in Shasta County, California, and the first known occurrence of Triassic ichthyosaurs from Mexico. Some remains are well preserved, but in general they are fragmented, structurally distorted, and incomplete; however, they enhance the current understanding of the morphology of a species that has been known hitherto only from an even more incomplete holotype. The material is the first from any Shastasaurus that preserves the anterior portions of the skull and lower jaw and implanted teeth. Revised diagnoses for the genus and species are given on the basis of the new material. Biostratigraphic zonation furnishes an early Late Carnian age for the specimens, which is in accord with that for the holotype.

Type
Research Article
Copyright
Copyright © The Paleontological Society 

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