Neusticemys neuquina (Fernández and de la Fuente, 1988) is a turtle from the Upper Jurassic of the Neuquén Basin, Patagonia, Argentina. Here we describe in detail a new skull, lower jaw, and a vertebra, utilizing both traditional anatomical description and computed tomography (CT). New diagnostic cranial characters of Neusticemys neuquina are: a round depression on the ventral surface of the basisphenoid, a relatively larger oval foramen nervi trigemini, and reduced and steepened triturating surfaces on both the maxilla and dentary. The new morphological information presented in this study was included in a phylogenetic analysis, the primary result of which was recovery of Neusticemys neuquina within Thalassochelydia. Characters recognized as synapomorphies of this clade include: (1) anterolateral recess of the anterior surface of the quadrate positioned lateral to the processus trochlearis oticum, (2) presence of a fossa on the supraoccipital-opisthotic-exoccipital contact area, (3) foramina anterius caroticus cerebralis located close together but independently perforating the basisphenoid, and (4) the presence of the splenial in the mandible. Two contrasting dispersal scenarios could explain how this species of Thalassochelydia can be found outside of Europe. The presence of Neusticemys neuquina in the Neuquén Basin could be the consequence of an early dispersion event, for which we lack intermediate forms, or it could be the result of a later event once the clade was already established in Europe.

We report new occurrences of Testudinidae and Chelidae from 11 different fossil sites in the Huayquerías and Tunuyán formations (late Miocene–Pliocene) in the Huayquerías del Este, Mendoza, Argentina. A total of 36 specimens were collected, representing at least three taxa from two different clades: 80.6% Testudinidae and 19.4% Chelidae. Testudinids are present throughout the stratigraphic succession, in alluvial, fluvial, and interdune sedimentary environments, represented by dorsal and plastron carapace plates, with some remains of the appendicular skeleton. A complete articulated plastron with some peripheral plates of the carapace was also recognized and is assigned to the extant species Chelonoidis chilensis, representing the oldest record for this taxon (late Miocene, Messinian). Another possible morphotype was recognized in the form of a large scapular girdle and femur that likely corresponded to an individual with a dorsal carapace of about 80 cm. This assemblage of small and large tortoise species is recognized for first time in the Messinian Age/Stage of Mendoza. Chelids are mostly restricted to fluvial deposits in the upper part of the Huayquerías Formation, except for two specimens which appear in the lower part. One specimen is represented by a right half plastron of an indeterminate Chelidae species which could correspond to a carapace of up to 24 cm in length with plastral lobes narrower than those observed in Phrynops species. Another specimen is characterized by a large costovertebral tunnel in the carapace, peripheral plates of the posterior margin of the carapace with ornamentation of fine grooves forming irregular polygons.

During the Antarctic summer campaigns and as a result of paleontological fieldworks 2013-2015 several mosasaur remains have been collected from the upper Maastrichtian López de Bertodano Formation exposed at Marambio (=Seymour) Island, of the Antarctic Peninsula. One of these specimens preserves part of the skull and dentition, which represent one of the few known skulls from Antarctica. The new specimen (MLP 15-I-24-41) is similar to member of the mosasaur tribe Plotosaurini, sharing the same fronto-parietal suture pattern, and a similar dental morphology as some of the species assigned to the genus. As the specimen is not complete enough to propose a new name it is referred to Mosasaurus sp. The presence of these remains on the southern hemisphere represents one of the most complete records of a Mosasaurus mosasaur.