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Palaeoecology of the marine reptiles of the Redwater Shale Member of the Sundance Formation (Jurassic) of central Wyoming, USA

Published online by Cambridge University Press:  03 July 2013

JUDY A. MASSARE*
Affiliation:
Earth Sciences Department, SUNY College at Brockport, Brockport, NY 14420, USA
WILLIAM R. WAHL
Affiliation:
Wyoming Dinosaur Center, Thermopolis, WY 82443, USA
MIKE ROSS
Affiliation:
2614 Navarre Street, Casper, WY 82601, USA
MELISSA V. CONNELY
Affiliation:
Earth Science Department, Casper College, Casper, WY 82601, USA
*
Author for correspondence: jmassare@brockport.edu

Abstract

The Redwater Shale Member (Oxfordian) of the Sundance Formation was deposited in the foreland basin of the Cordillera during the last and largest marine transgression of the Jurassic in North America. One ichthyosaur (Ophthalmosaurus natans), two cryptocleidoid plesiosaurs (Tatenectes laramiensis, Pantosaurus striatus) and one pliosauromorph (Megalneusaurus rex) are known from the Redwater Shale Member. Ichthyosaurs are much more abundant than plesiosaurs, making up almost 60% of the fauna. No actinopterygian fish have been found, although four species have been identified from the lower Sundance Formation. At least one hybodont shark and one neoselachian are known from rare isolated teeth. The main food source for the marine reptiles was belemnoids, as indicated by preserved gut contents for all four species. In comparison, the better known and slightly older Peterborough Member of the Oxford Clay Formation of England, has a much higher taxonomic and ecological diversity, especially in the plesiosaurs, marine crocodiles, and fish. The lower diversity in the Redwater Shale Member probably reflects a much lower primary productivity in the Sundance Sea, as well as restricted migration from the open ocean to the north.

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Type
Original Articles
Copyright
Copyright © Cambridge University Press 2013 

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