In 1988 Zhang Yihun named and described the type speciesProtognathus oxyodon.[1] The generic name was derived from Greek πρῶτος, protos, "first", and γνάθος, gnathos, "jaw". The specific name is derived from Greek ὀξύς, oxys, "sharp", and ὀδών, odon, "tooth". However, the generic name was preoccupied, already in use, by a genus of carabidbeetle, Protognathus (Basilewsky, 1950[2]) which is considered a synonym of Pseudognathaphanus (Schauberger, 1932).[3] The species was therefore renamed into the combinatio novaProtognathosaurus oxyodon by George Olshevsky in 1991.[4]
Protognathosaurus is known only from a fragmentary lower jaw, holotypeCV 00732 (= ChM V732) found in a layer of the Shaximiao Formation dating from the Bathonian-Callovian. The fragment consists of the front left dentary and shows eighteen tooth positions, some still containing sharp replacement teeth, after which the genus was named. Most researchers consider Protognathosaurus to be a nomen dubium.
^Zhang, Y., 1988, The Middle Jurassic Dinosaur Fauna from Dashanpu, Zigong, Sichuan. Vol. II. Sauropod Dinosaurs (I), Sichuan Publishing House of Science and Technology, Chengdu, China, 89 pp
^Basilewsky, P. (1950b) Nouveaux Cossyphodides du Congo belge (Col. Cossyphodidae). Revue de Zoologie et de Botanique Africaines, 43, 240–243.
