Oscar Edward Wilson

Turtles provide an important link between terrestrial and aquatic ecosystems, acting as both predators and prey, while also being an important host for a range of parasites. The dermal armor that characterizes the group ensures their abundance in the vertebrate fossil record and preserves evidence of biotic interactions. We evaluated the ichnofauna and body size distributions of turtles from the early Paleocene Tiupampa Fauna (Santa Lucía Formation), Bolivia, to reconstruct aspects of the Tiupampan ecosystem. We observed bite traces in several specimens of Lapparentemys vilavilensis from the ichnogenera Brutalichnus , Linichnus , Machichnus , and Nihilichnus , which are consistent with predation or scavenging by crocodyliforms, including sebecids and possibly dyrosaurids. The carapaces and plastra also include evidence of invertebrate activity ( Karethraichnus and cf. Thatchtelithichnus ), interpreted to represent parasitism, possibly by leeches or trematodes. Evidence of fungal or bacterial infection, through records of ichnogenera such as Gunnellichnus or Violinichnus , is rare, but may suggest host–parasite specialization was present shortly after the Cretaceous–Paleogene boundary. The rarity of these features and the general stability of the population, assessed through body size distributions, possibly suggests that the turtles of Tiupampa were not experiencing particularly high levels of environmental stress.

The early Oligocene Tinguiririca Fauna from the Abanico Formation, central Chile, is the earliest mammal fauna dominated by high-crowned (hypsodont) herbivores known globally. The drivers of early hypsodonty in South America are thus of considerable interest. We reconstruct the palaeoenvironment for Tinguiririca based on: (1) generalised linear latent variable models (GLLVMs), which compare body mass distributions of Tinguirirican and modern South American herbivores; and (2) reconstructed diets of Tinguiririca fauna notoungulates inferred from dental mesowear. Based on GLLVMs, the Tinguiririca Fauna’s palaeoenvironment is interpreted as relatively warm (22˚C mean annual temperature), dry (1200 mm yr ^-1 mean annual precipitation) and open (23% tree cover). The Brazilian Caatinga is the closest modern South American analogue to the dry, low-vegetation-density palaeoenvironment inferred for Tinguiririca. We interpret the fauna’s notoungulates as browsers, based on their sharp ectoloph wear facets. To test this interpretation, we also analysed the mesowear angles and relative crown heights of a broad array of leontiniid and homalodotheriid notoungulates, two clades specialised for high browsing that never attained the levels of hypsodonty seen in other notoungulates. Both have sharp mesowear and greater relative crown heights than modern high browsers. Our data suggest that neither gradual habitat change nor increased levels of volcaniclastic sedimentation alone caused the early attainment of hypsodonty in notoungulates. Alternative explanations, such as one or more rapid pulses of environmental change driving the increase in hypsodonty or the unique taxonomic composition of South American faunas, must be invoked to explain the marked increase in crown height from preceding time periods into the Tinguirirican South American Land Mammal Age.

The Middle Miocene La Venta assemblage from La Tatacoa Desert, Huila Department, Colombia (Fig. 1), represents the most diverse and well-sampled fossil vertebrate community in the Neotropics (Carri...

The fossil record is the most important tool in palaeosciences, so continually reviewing and attempting to reduce biases in its collection is necessary to curate the best possible record of past life on Earth. Biases in the fossil record are introduced through both biological processes and data collection. Here we have investigated the extent to which anthropocentric data collection has contributed to sampling bias in the assembly of the current fossil record. We have found that the current fossil record (represented in this study by the NOW database) is anthropocentrically biased, both temporally and spatially. Specifically, fossil locality density is higher in time periods when hominins are found, and in known hominin-bearing locations. This demonstrates the need to stop essentializing the narrative of human evolution in paleoscience to reduce bias in sampling of fossil localities.

The arrival of humans to the Americas at the end of the Pleistocene has been one of the foundations of the hypothesis that hunter-gatherer groups had a direct role in the extinction of megafauna. However, empirical evidence of the exploitation of megafauna by humans and associated chronological context are still scarce, especially in South America. Using evidence of modifications on osteological remains, we provide a reassessment of the megafauna that was exploited at the classic Taima-Taima site (Venezuela), with an updated chronology and paleoenvironmental inferences. Our results show that, at least, five species of extinct megaherbivores were probably exploited at the site, expanding the previous records, restricted to the proboscidean Notiomastodon platensis and the giant armadillo Glyptotherium cf. G . cylindricum . The new data of the other exploited taxa include the terrestrial sloth Glossotherium , the macrauchenid cf. Xenorhinotherium bahiense and a toxodontid; both killing and slaughtering activities were likely practised at the site. Seven new enamel radiocarbon dates show an age of 15.3–17.8 cal kyr BP for the fossiliferous strata, although this is likely to be a minimum age given the material’s propensity for modern carbon uptake. The study of phytoliths and starch grains from the dental calculus of N. platensis identified five plant taxa from the phytoliths: arboreal dicotyledons, Poaceae, Marantaceae, Asteraceae and Arecaceae. Ecometrics studies of dental diversity reveal how no other single site on the continent preserves such a diversity of grazing and browsing megaherbivores exploited by humans.

The Early to Middle Miocene mammal assemblage of the Castilletes Formation, Colombia records a diverse assemblage of mammals in the northern Neotropics prior to the Great American Biotic Interchange. We identify new records of herbivorous mammal taxa, with additional specimens of Huilatherium sp. and the first records of cf. Pericotoxodon sp., Miocochilius cf. M . anomopodus and ‘ Scleromys’ sp. All these genera are shared with other tropical Middle Miocene assemblages, including La Venta (Colombia) and Fitzcarrald (Peru) and increase the faunal similarity among them. Ecometric analysis of dental traits suggests a habitat change between the assemblages of the Castilletes Formation and the Ware Formation (Late Pliocene), consistent with results from other proxies that show increased opening and drying. In combination, these results support the utility of ecometric methods in Neogene South America and emphasise the importance of taxonomic revisions for these taxon-independent methods.

Bilophodont tooth morphology is found in various groups of extant and fossil herbivores, including tapirs, marsupials, deinotheres, and two groups of Paleogene South American native ungulates: the xenungulates and pyrotheres. Mesowear angles, an extension of the traditional mesowear method for reconstructing diet based on the balance between attrition and abrasion, have been previously applied to deinotheres using the inclination of their wear facets. We measured mesowear angles from South American fossil bilophodonts (tapirs, xenungulates, and pyrotheres) from wear facet inclination or dentine valleys and compared those to results from some modern bilophodont taxa. Mesowear angles in modern bilophodonts match the dietary predictions based on observed diet and highlight the potential of these angles for dietary reconstruction in fossil groups. Xenungulates and fossil tapirs all show sharp mesowear angles (< 106˚), indicating a browsing feeding behaviour. In contrast, pyrotheres show significant dietary variation. Some taxa (e.g., Griphodon peruvianus and Pyrotherium romeroi ) show steeply inclined facets indicating browsing. Rounded, shallower facets in Propyrotherium saxeum are interpreted as evidence of frugivory, while Pyrotherium macfaddeni has relatively shallow facets indicating a mixed-feeding ecology. High mesowear angles in Proticia venezuelensis and Colombitherium tolimense support grazing in the colombitheriids, a group with controversial phylogenetic affinities. There is huge potential for the further application of mesowear angles in other bilophodont taxa for dietary reconstruction, and we propose that angles measured in bilophodonts could be compared to those from other dental morphologies for palaeoenvironmental reconstruction.