Rocasaurus

Rocasaurus (meaning "General Roca lizard") is a genus of titanosaurian sauropod that lived in South America. Rocasaurus was discovered in Argentina in 2000, within the Allen Formation which is dated to be middle Campanian to early Maastrichtian in age (75 to 70 million years ago in the Late Cretaceous). This genus grew up to 8 m long, making it one of the smaller sauropods. It seems to be closely related to saltasaurid dinosaurs, like Saltasaurus and Neuquensaurus.

The type species, Rocasaurus muniozi, was formally described by Leonardo Salgado and Azpilicueta in 2000. New specimens were described in 2021.

Discovery and naming
Between 1989 and 1994, expeditions of the National University of Comahue and the Carlos Ameghino Provincial Museum collected titanosaur fossils from the locality of Salitral Moreno, 25 km south of the city of General Roca in Río Negro Province, Argentina. In 2000, Leonardo Salgado and Claudia Azpilicueta described some of these remains as representing a new genus and species, Rocasaurus muniozi. The genus name refers to its discovery near General Roca and the species name honors Juan Carlos Muñoz, director of paleontology at the Carlos Ameghino Provincial Museum, for his support of paleontological research in the region.

Fossil record
The holotype of Rocasaurus muniozi, MPCA-Pv 46, is a partial skeleton of a juvenile individual including partial cervical vertebrae, partial dorsal vertebrae, caudal vertebrae, both ilia, ischia, and pubes, and the left femur. Other elements of R. muniozi found at Salitral Moreno include three cervical vertebrae and several caudal vertebrae. Additional remains of R. muniozi are known from another locality, Salitral Ojo del Agua, and include partial cervical vertebrae, a partial dorsal vertebra, and a fragmentary ischium.

Phylogeny
Rocasaurus in a cladogram after Navarro et al., 2022: