Teleosauroid extinction at the Jurassic/Cretaceous boundary has been hypothesized to be an artifact of sampling only temperate paleolatitudes. Here, we describe the definitive youngest record of Teleosauroidea, from the upper Barremian of the paleotropics. The preserved material consists of dorsal vertebrae, dorsal ribs, dorsal and ventral osteoderms, and epipodial remains. We refer the specimen to Teleosauroidea based on the large hourglass-shaped amphiplatyan morphology of the dorsal centra and rectangular dorsal osteoderms, which are much wider than long and have a straight anterior edge. The South American specimen is one of the largest known teleosauroids, with an estimated body length of 9.6 m. This is the first evidence of a marine crocodylomorph recorded from the Paja Formation of Colombia. The survival of Teleosauroidea in the paleotropics of northern Gondwana following the group's extinction in Europe supports the hypothesis that water temperature played a role in controlling the diversity and distribution of these large marine predators.

Acknowledgment of intraspecific variation is an important part of a reliable species diagnosis. For mammalian taxonomy, tooth morphology is an especially important trait and, therefore, the morphological variability of these structures is also greatly significant. Here we describe major dental variation present for Protolipterna ellipsodontoides Cifelli (Litopterna) based on a sample of more than 500 teeth and provide a differential diagnosis distinguishing the species from its sister taxa. Initially, the sample was carefully observed under stereomicroscope in order to identify variable traits. Further variable features were also highlighted by a geometric morphometric analysis. We conducted statistic tests to assess the likelihood that the fossils belong to a single species and the single identity of the sample was recovered. A great deal of our results show that structures like the parastyle, hypocone, conular cristae and ectoflexus can show different degrees of development for the same species. The tooth outline may also show some variation in shape and proportions. Many of those features are used as characters of phylogenies, however, the results obtained indicate these traits to be inappropriate for this sort of study, as they are variable within a single species. Some accessory cusps were also found, but they have very low frequency. Furthermore, these traits lack a clear phylogenetic signal and hence are of dubious validity to taxonomy and systematics.

Autobranchia Grammysiidae bivalves from the Silurian and the Devonian beds of Central Andes Basin of Western Gondwana are herein presented. They were collected in nine scattered outcrops in Eastern Cordillera, Western Altiplano, Interandean and Subandean Bolivia. A total of 34 specimens of a good to regular state of preservation were studied. It is the first time that the genera Grammysia and Grammysioidea from the Eifelian and the Givetian of Bolivia are formally described. This is the first record of Andinodesma radicostata from Ludlowian to Pridolian sandstones of the Interandean of Villagranado and Sobo Sobo. It is the first Bolivian record of the cosmopolitan genus Sanguinolites from the Eifelian of Altiplano (Belén) and Subandean (Alarache). In this paper, the oldest record of the endemic species of Pholadella radiata from the Emsian of Western Gondwana (Icla and Sobo Sobo) is reported. It documents the important dispersion of the Grammiisydae Family during the Eifelian and Givetian times in the Central Andes with genera as Grammysioidea, Grammysia, Sanguinolites and Pholadella. This research contributes to the as yet inaccurately known Silurian and Devonian paleogeography of the Central Andes Basin and is an update of very few and old reports and presents new findings of Grammysiidae bivalves from Bolivia.

The family Chaperiidae reaches its highest biodiversity in the southern hemisphere. The main morphological feature characterizing the family is a pair of calcareous laminar structures associated with the insertion of the operculum occlusor muscles. The aim of this study is to describe Aluis spinettai gen. et sp. nov., from material collected in the Monte León, the Chenque, and the Puesto del Museo formations (early Miocene, Patagonia, Argentina). A. spinettai has erect bilaminar colonies, crenulated sutures between zooids, an extensive cryptocyst and spherical ovicells; gymnocyst, oral spines, and avicularia are absent. The new species exhibits a remarkable morphological convergence with a species of Aspidostoma from the early Miocene (Chenque Formation) of Patagonia. In some areas of the colony, the cryptocysts were pierced by circular drill holes made by an unknown predator. The stratigraphic distribution of A. spinettai ranges from ∼19 to 17 Ma (Burdigalian). Its presence suggests a correlation between the upper levels of the Monte León Formation and the lower levels of the Chenque Formation. The paleogeographic distribution of this new species spans at least 500 km along the southern Atlantic coast of South America. The living representatives of the Chaperiidae in the Southwest Atlantic do not seem related to A. spinettai.