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A new basal notoungulate, Nanolophodon tutuca gen. et sp. nov., is described. This is represented by maxillary and dental fragments and by isolated teeth. The holotype and referred material were found at the “1968 Fissure” of the Itaborai Basin, Rio de Janeiro State, Brazil. This basin has been regarded as early Eocene in recent contributions. The generalized appearance and brachydonty of the studied specimens, together with the presence of certain typical traits (poorly developed entolophid, well-developed metacone column, etc.) indicate that N. tutuca can be considered among the group of genera traditionally known as henricosborniids, easily distinguishable from Typotheria by the absence of crista 1 and from Toxodontia by the absence of crista intermedia. It is also different from all other henricosborniids by a combination of characters, such as the presence of a long crochet, the development of two small cristae in the ectoloph, and the large paraconid, among others. In the context of a phylogenetic analysis performed, we do not find conclusive evidence about the synonymy between Itaboraitherium atavum and Othnielmarshia pristina. In turn, we question the reference of these forms as henricosborniids, based on the complex occlusal dental pattern observed in both cases. Finally, based on the observations made in the present study, we discuss the identification of the paraconid in notoungulates, which may be associated with some cusps located mesially to the metaconid and identified as pseudoparaconids in past studies.

Nothrotherium maquinense, Ahytherium aureum and Australonyx aquae are ground sloths endemic of the late Pleistocene of the Brazilian Intertropical Region for which, as opposed to other xenarthrans such as megatheriid sloths and glyptodonts, no information regarding pathological conditions is available. Herein, we describe, based on an anatomopathological examination, four types of lesions for N. maquinense (spondyloarthropathy, Schmorl's node, vertebral trauma and unspecific infection) and one lesion for A. aureum (osteochondritis dissecans). No lesions were observed in A. aquae. Although several different diseases have been diagnosed, considering the significant number of specimens (2,232) and individuals (41) analyzed, low prevalence marks them all.

Acknowledging intraspecific variation is an important part of a reliable species diagnoses. 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 all dental variation present for Protolipterna ellipsodontoides based on a sample of more than 500 teeth and provide a differential diagnoses distinguishing from its sister taxa. Initially, the sample was carefully observed under stereo microscope in order to indentify variable traits. Further variable features were also highlighted by a geometric morphometric analysis. We conducted statistic tests to make sure all sample belong to the same 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 current results pointed that those traits are inadequate 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. These traits, however, does not have a clear phylogenetic sign and should be not be unadvisedly used in any taxonomy or phylogenetic research. doi: 10.5710/AMGH.11.08.2019.3250

The sparassodonts were the main mammalian predators during most of Cenozoic in South America. The lower Eocene Itaborai Basin/Formation includes the second oldest fossil records of this group in South America: Patene and Nemolestes. Patene is by far the most abundant sparassodont from this formation, with more than 30 specimens referable to a single taxon, Patene simpsoni. Some specimens recovered from the Quebrada de Los Colorados Formation (former Lumbrera Formation – middle Eocene) in Northwestern Argentina have been also referred to P. simpsoni. In order to test the affinities of Patene and the taxonomy of the Argentinean specimens, we performed a review of the genus. We concluded that the specimens from Northwestern Argentina show significant differences from the Brazilian specimens: smaller size, paraconid more developed; metaconid, entoconid and hypoconid more reduced. As a result, the specimens from the Quebrada de Los Colorados Formation were assigned to a new species, Patene coloradensis. Our phylogenetic analysis supported previous hypotheses that exclude Patene from the “Hathliacynidae”, as the former was recovered as an earlier divergent lineage. The results also supported the hypothesis that Allqokirus australis and Mayulestes ferox from the Tiupampa Basin (El Molino Formation, lower Paleocene – Tiupampian), Bolivia, are the oldest known representatives of the Sparassodonta. The results also supported the monophyly of the Pucadelphyida with the inclusion of the Jaskhadelphyidae and closely related taxa in addition to the Pucadelphyidae + Sparassodonta. The Late Cretaceous, North American Varalphadon was not recovered in our phylogenetic analysis as a representative of the Sparassodonta.Based on our results, the Sparassodonta should be considered, based on the current fossil record, as a South American endemic lineage. doi: 10.5710/AMGH.06.05.2019.3222

Titanosauria is a clade of sauropod dinosaurs that includes some of the largest terrestrial animals ever recorded. An outstanding feature of some species of this group is the presence of osteoderms, which are bony deposits on the skin that form scales, plates or other structures. Only six osteoderms have been identified from Brazil. Herein, we describe the first titanosaurian osteoderm from the Potiguar Basin (Early–Late Cretaceous) and discuss Brazilian titanosaur osteoderm diversity, their taxonomy and the functional implications. The specimen (UFRJ-DG 549-R) is bilaterally symmetrical and is assigned to the ellipsoid morphotype. The most interesting feature is the large cavities separated by thin trabeculae. This pattern, according to recent interpretations, suggests that titanosaur osteoderms functioned as a source of calcium. However, the function(s) of titanosaur osteoderms remain(s) open to debate. Compared with the other reported osteoderms from Brazil, the Potiguar osteoderm shows more similarities with an osteoderm of Ibira (Bauru Group, Turonian–Santonian) than with material collected from the Sao Luis Basin (Albian–Cenomanian) despite their greater geographical and temporal proximity. The Potiguar and Ibira osteoderms are of the ellipsoid morphotype, with no cingulum and several pits on the external surface. More findings are necessary to clarify whether the Potiguar material represents a different armored titanosaurian species in northeastern Brazil.