Titanosaurs were the predominant herbivores during the Late Cretaceous, inhabiting all continents. This clade was especially diverse in South America with some of the largest and smallest sauropod species known to date. Despite its diversity, the evolution of this clade is far from being well-known, although some recent analyses have begun to find some consensus in their results. Rinconsauria (defined as the least inclusive clade containing Rinconsaurus and Muyelensaurus) includes small titanosaurs and is considered as closely related to the lineage of giant titanosaurs, Lognkosauria (defined as the least inclusive clade containing Futalognkosaurus and Mendozasaurus), both being part of the recently named clade Colossosauria. The titanosaur Rinconsaurus caudamirus, from the Bajo de la Carpa Formation (Santonian), Río Negro, Argentina, is represented by several axial and appendicular elements from at least four specimens. This taxon was only briefly described when it was named and most of its originally proposed autapomorphies are now recognized as having a more widespread distribution amongst titanosaurs. Herein we present a detailed osteological description of the axial skeleton and a revised diagnosis for this taxon that firmly establishes its validity. Based on comparisons with other titanosaurs, we found three new possible autapomorphies for the axial skeleton of Rinconsaurus, which added to its original combination of characters, endorsing this taxon as a valid genus. Besides, this revision of Rinconsaurus provides additional osteological data that will contribute to a better resolution of titanosaur phylogeny, contributing at the same time to our understanding of the clade Rinconsauria.

An important parameter in studying the macroevolutionary history of a clade is the variation of its body size. However, the analysis of this parameter in archosauromorphs has been restricted to Archosauria, and the disparity in body size has not been exhaustively explored. In the present work, we study the variation in body size of more than 400 known Permian–Early Jurassic archosauromorph species in the context of their early evolutionary radiation. We analysed the disparity of body size over time and the relationship between this parameter and the palaeolatitudinal distribution of species. From these analyses, it was found that the disparity of body size of archosauromorphs increased after the Permian/Triassic boundary. In the case of Pseudosuchia and Pan-Aves (=Avemetatarsalia), the Triassic/Jurassic extinction shows a pattern of selective extinction of medium to large-sized forms, and their body size disparity decreased significantly. In contrast, dinosaurs increased their body size and their disparity did not change significantly after the Triassic/Jurassic extinction event. Regarding the relationship between body size and geographic distribution, pseudosuchians show a pattern of body size decrease towards higher palaeolatitudes, i.e., a converse Bergmann's rule. These results could be linked to physiological factors since many groups of extant ectothermic animals show a similar pattern. These analyses help to elucidate the complex body size evolutionary dynamics in the early radiation of Archosauromorpha, as indicated by the different patterns observed across its subclades.

We describe a well-preserved humerus of Homunculus patagonicus, a stem platyrrhine from the late early Miocene of the Santa Cruz Formation, Santa Cruz Province, Argentina. The distal part of a humerus was collected by Carlos Ameghino and figured in the 19^th Century, but is now lost. Other described postcranial elements, also collected by him include a femur and a partial radius. Comparative observations are made with living and extinct platyrrhines, Oligocene African anthropoids, and extant strepsirrhines. Homunculus patagonicus was a robustly built arboreal quadruped that weighed between 2.2 and 2.6 kg. There is no evidence that the elbow could be fully extended as in living suspensory platyrrhines like Ateles. The medial orientation of the epicondyle suggests that the finger and wrist flexors were not aligned with the long axis of the limb, a distinction from more cursorial monkeys (extant cercopithecoids and the Cuban Pleistocene fossil platyrrhine Paralouatta have retroflexed medial epicondyles). Overall, the morphology is typically platyrrhine although the bone is quite robust. The robustness of the humerus is most comparable to that of early anthropoids from Africa rather than any extant platyrrhine.

There are three extant species of wild canids in Venezuela: Urocyon cinereoargenteus, Cerdocyon thous, and Speothos venaticus, excluding the feral domestic dog (Canis familiaris). However, a review of paleontological material that was published previously, along with newly reported ancient specimens, reveals a distinct historical diversity for the same region. The gray fox, U. cinereoargenteus, is the only small-sized taxon and the only Vulpini (true fox) identified to date in the fossil record of Venezuela; its presence is limited to the late Pleistocene of the Mene de Inciarte site, Zulia State. In contrast, large canids are more abundant. Aenocyon dirus (subtribe Canina), the dire wolf from the late Pleistocene, was reported from the sites El Mene de Inciarte, Muaco in Falcón State, and for the first time in El Breal de Orocual (ORS20) in Monagas State. The genus Protocyon, a native South American canid (subtribe Cerdocyonina), is recognized in the country from late Pleistocene Inciarte (Protocyon troglodytes sensu lato), and late Pliocene–early Pleistocene Orocual (ORS16) (Protocyon orocualensis sp. nov.). Finally, we report a possible genus Theriodictis from the late Pleistocene Orocual; this is a Cerdocyonina not previously mentioned for the northern region of South America. These records present broader diversity and suggest a more complex evolutionary history than previously thought for South American canids.