Mount Saint Peter
Around 1765 the skull of a "Mosasaurus" was discovered here in a limestone quarry, one of the first recognised reptile fossils, which was later acquired by the Teylers Museum in Haarlem. A more famous "Mosasaurus" fossil was found between 1770 and 1774 but was confiscated by the French in 1794 and is now in the Muséum national d'Histoire naturelle in Paris. Later dinosaur remains were discovered here as well, belonging to "Betasuchus" and "Orthomerus", as well as turtles and fossils of smaller creatures of the sea.
Timeline of mosasaur research
Russell also published additional information and speculation on mosasaur biostratigraphy. He reported the presence of mosasaur vertebrae up to 90 million years old among the Turonian fossils curated by the University of Kansas Museum of Natural History. Another of this work's significant contributions to mosasaur biostratigraphy concerned the mosasaurs of the Smoky Hill Chalk. Russell devised two biostratigraphic zones based on the Chalk's mosasaur fossils. The lower zone was characterized by "Clidastes liodontus", "Platecarpus coryphaeus", and "Tylosaurus nepaeolicus". The upper was home to "Clidastes", "Platecarpus ictericus", and "Tylosaurus proriger". He regarded "Platecarpus" and "Tylosaurus" as deep water animals but concluded that the biostratigraphic evidence from the Smoky Hill mosasaurs suggested that the Chalk's depositional environment was becoming shallower and nearer to the ancient coastline over time. Russell also argued that by the end of the Late Cretaceous, mosasaurs were converging on the body plan that characterized the first ichthyosaurs during the Triassic period and gradually replacing these older marine reptiles.