Gustavo Ribeiro de Oliveira

New Information about Pelomedusoides (Testudines: Pleurodira) from the Cretaceous of Brazil

Brazilian turtle remains date from the Cretaceous and have been recovered from in 11 different basins. Two of these are of particular importance because of the richness of species and specimens: Araripe (Early Cretaceous) and Bauru (Late Cretaceous). Here we present information based on new material that adds to our understanding of the diversity of turtles from Araripe Basin and provides a basis for discussion of the taxonomic status of some species from Bauru Basin. A new specimen from the Araripe Basin that is from the Crato Formation, although generically indeterminate is proposed to be the oldest representative of the clade Podocnemidera. This allocation would extend the stratigraphic range of the Podocnemidera to the Aptian/Albian, matching that of its sister group, the Pelomedusera. New specimens from the Bauru Basin allow a better understanding of the morphology of the shell in Roxochelys and an assessment and interpretation of diagnostic features used to distinguish Bauru Basin endemic forms. Our preliminary examination of this material leads us to conclude that the diversity described in this basin is overestimated. As consequence, we argue that Bauru Basin includes only two well diagnosed species of turtles: Roxochelys wanderleyi and Bauruemys elegans.

The oldest plesiosaur (Reptilia, Sauropterygia) from Antarctica

Antarctic plesiosaurs are known from the Upper Cretaceous López de Bertodano and Snow Hill Island formations (Campanian to upper Maastrichtian), which crop out within the James Ross Basin region of the Antarctic Peninsula. Here we describe the first plesiosaur fossils from the Lachman Crags Member of the Santa Marta Formation, north-western James Ross Island. This material constitutes the stratigraphically oldest plesiosaur occurrence presently known from Antarctica, extending the occurrence of plesiosaurians in this continent back to Santonian times (86.3–83.5 Mya). Furthermore, MN 7163-V represents the first plesiosaur from this region not referable to the Elasmosauridae nor Aristonectes, indicating a greater diversity of this group of aquatic reptiles in Antarctica than previously suspected.