What is "diplosaurus"

Diplosaurus is an extinct genus of goniopholidid mesoeucrocodylian. Fossils have been found from the western United States and range from Late Jurassic to Early Cretaceous in age. The genus was first named and described in a paper written in 1877 by Othniel Charles Marsh. The generic name, derived from Greek διπλόος, diploos, "double", probably refers to the "biconcave vertebrae" Marsh mentions as a distinctive trait compared to modern forms. The type species is Diplosaurus felix. In 1890 Karl Alfred von Zittel recombined this with Goniopholis into a Goniopholis felix, but today this is generally rejected.

Along with D. felix (sometimes misspelled D. felise), a second species of Diplosaurus was constructed in 1877 by Marsh after he recombined Hyposaurus vebbii, named by Edward Drinker Cope in 1874, with Diplosaurus into a new combination, Diplosaurus vebbii. D. nanus was named by Marsh in 1895 but is now considered to be a nomen dubium.