2002/04/01 by Michael J. Everhart · 18 citations
Earth and Planetary Sciences · Environmental Science · #Paleontology and Evolutionary Biology #Evolution and Paleontology Studies #Amphibian and Reptile Biology #Squamata #Type specimen #Type (biology) #Geology #Archaeology #Biology #Paleontology #Zoology #Geography #Genus
paper · doi:10.1660/0022-8443(2002)105[0033:ndocma]2.0.co;2
published in Transactions of the Kansas Academy of Science 105(1 & 2), 33-43 (Kansas Academy of Science)
openalex publication_date 2002/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2025/11/06
Tylosaurus nepaeolicus (Cope 1874) is one of the least well known of the five species of mosasaurs that are recognized from the lower Smoky Hill Chalk Member (upper Coniacian) of the Niobrara Formation in western Kansas. In describing the type material, Cope stated that this species was one-third or less the size of T. proriger (Cope 1869), a species that appeared during the Santonian and is well represented in the middle and upper chalk. Additional data provided by Russell from a review of specimens in the American Museum of Natural History and the Yale Peabody Museum showed that most T. nepaeolicus material is somewhat larger than the type specimen, but is significantly smaller than adult T. proriger specimens. Measurements of two additional T. nepaeolicus skulls, an articulated series of Tylosaurus sp. vertebrae and other material in the Sternberg Museum of Natural History suggest that this species approached 8–9 m in size by the end of the Coniacian and was approximately the same size as a large T. proriger reported from the lower Santonian. Although time and other morphological features separate T. nepaeolicus from T. proriger, the two species are closer in size than previously reported.