Palaeoenvironment and palaeoecology of three Cretaceous snakes: Pachyophis, Pachyrhachis, and Dinilysia

The palaeoecology of three Late Cretaceous snakes is evaluated. Pachyophis woodwardi Nopcsa, 1923 and Pachyrhachis problematicus Haas, 1979, are Cenom anian in age and are found in carbonate rocks deposited in marine inter-ree f basin environments of the European and African Tethys Sea. Dinilysia pata gonica Woodward, 1901, Coniacian in age, is considered closely allied to li ving anilioid snakes, and is found in elastic rocks deposited in a terrestr ial inter-dune basin environment in northern Patagonia, Argentina. All thre e snakes are known from well preserved and articulated specimens found in s ediments where derailed sedimentological and taphonomic analyses are possib le. Pachyophis and Pachyrhachis were laterally compressed, have pachyostoti c ribs and vertebrae, and small, narrow heads. These two snakes are interpr eted as aquatic predators living in and around the margins of reef mounds o n a shallow water carbonate platform. Dinilysia was a large bodied snake wi th a relatively large head, and is interpreted here as a terrestrial predat or that lived in a dry, interdune basin environment dominated by aeolian se dimentation. Sedimentary units preserve ichnological evidence of burrowing insects and rooting plants.