Two new species of the side necked turtle genus, Bairdemys (Pleurodira, Podocnemididae), from the Miocene of Venezuela

The side-necked turtle genusBairdemys (Podocnemididae,Shweboemys Group) from the Miocene of Venezuela and Puerto Rico is revised, and four species are diagnosed on the basis of skull characters; two are de-scribed as new.B. hartsteini Gaffney & Wood, 2002, from the Cibao Formation of Puerto Rico, is characterized by a higher skull, with a straight labial ridge and a premaxillary notch;B. venezuelensis (Wood & Díaz de Gamero 1971), from the Urumaco Formation of Venezuela, is characterized by the absence of a premaxillary notch, a high anterior triturating surface convexity, a deep posterior triturating surface concavity, and a short pterygoid mid-line contact;B. sanchezi, new species, from the Urumaco Formation of Venezuela, is characterized by a very low anterior triturating surface convexity and shallow posterior triturating surface concavity, a premaxillary notch, small size, and extensive temporal and cheek emargination;B. winklerae, new species, from the Urumaco Formation of Venezuela, is characterized by an elongate, narrow snout, with a concave labial ridge, and no premaxillary notch. Based on osteological and bone histological results, an additional strongly crushed skull and associated cara-pace fragment of a previously undetermined podocnemidid from the Urumaco Formation of Venezuela can be further referred toPodocnemis or a closely related taxon — again underscoring the importance of this formation as one of the major fossil lagerstätten of turtles in South America

New Glyptodont from the Codore Formation (Pliocene), Falcón State, Venezuela, its relationship with the Asterostemma problem, and the paleobiogeography of the Glyptodontinae

One of the basal Glyptodontidae groups is represented by the Propalaehoplophorinae (late Oligocene — middle Miocene), whose genera (Propalaehoplophorus, Eucinepeltus, Metopotoxus, Cochlops, andAsterostemma) were initially recognized in Argentinian Patagonia. Among these,Asterostemma was characterized by its wide latitudinal distribution, ranging from southernmost (Patagonia) to northernmost (Colombia, Venezuela) South America. However, the generic assignation of the Miocene species from Colombia and Venezuela (A.? acostae, A. gigantea, andA. venezolensis) was contested by some authors, who explicitly accepted the possibility that these species could correspond to a new genus, different from those recognized in southern areas. A new comparative study of taxa from Argentinian Patagonia, Colombia and Venezuela (together with the recognition of a new genus and species for the Pliocene of the latter country) indicates that the species in northern South America are not Propalaehoplophorinae, but represent the first stages in the cladogenesis of the Glyptodontinae glyptodontids, the history of which was heretofore restricted to the late Miocene — early Holocene of southernmost South America. Accordingly, we propose the recognition of the new genusBoreostemma for the species from northern South America and the restriction ofAsterostemma to the Miocene of Patagonia. Thus, the available data indicate that the Glyptodontinae would in fact have arisen in the northernmost regions of this continent. Their arrival to more southerly areas coincides with the acme of the “Age of Southern Plains”. The Propalaehoplophorinae are geographically restricted to Patagonia