Highly Specialized Diplodocoids: The Rebbachisauridae

L. SALGADO; GALLINA, P. A.; LERZO, L.; CANUDO, I

South American Sauropodomorph Dinosaurs

Springer Nature

Año: 2022; p. 165 - 208

With 17 species formally identified throughout the world,Rebbachisauridae is, at present, the best-represented group of South Americandiplodocoids, and it has a temporal record ranging from the Barremian up to theTuronian. Defined as all diplodocoids more closely related to Rebbachisaurusgarasbae than to Diplodocus carnegii, these sauropods are characterized by postcranialsynapomorphies (e.g., absence of the hyposphenal ridge on anterior caudalvertebrae; presence of spinodiapophyseal lamina in caudal vertebrae). Althoughrelatively complete skulls are known in only a few genera (Limaysaurus, Lavocatisaurus,and Nigersaurus), the whole cranial evidence indicates that they were highlyspecialized with respect to other diplodocoids (for instance Diplodocidae). SouthAmerica counts ten genera of Rebbachisauridae, most of them from the ArgentinePatagonia. They embrace a rather diverse group of basally branching forms (Amazonsaurus,Zapalasaurus, Comahuesaurus, and Lavocatisaurus), derived forms (as thelimaysaurines Limaysaurus and Cathartesaura and the rebbachisaurines Katepensaurusand Itapeuasaurus), together with forms of uncertain phylogenetic filiation (Rayososaurus). Rebbachisaurids were important in South America toward the endof the Early Cretaceous, integrating, at that time, the sauropod faunas together withmacronarians (Titanosauriformes) and other diplodocoids (Dicraeosauridae). Theypersisted up to at least the Turonian, being the last diplodocoids in becoming extinctglobally.