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Teeth from the Family Bovidae that are associated with our early humans ancestors are important for reconstructing paleoenvironments. However, age, degree of attrition, and taphonomic factors often make fossil identification difficult. A recent technique for classifying these teeth uses the size-and-shape of the occlusal surface as a summary of the surface, deriving features from this, and then using these features in machine learning classification algorithms. Bovid teeth have previously been classified using this method with features derived from coefficients of elliptical Fourier analysis (EFA). This study assesses the utility of using other shape representations for feature generation, specifically elastics shape analysis. Features were derived using this frame work for both shape only and size-and-shape (i.e. size is not considered a nuisance parameter), and those features were used as input for machine learning algorithms. We demonstrate that features derived elastic shape analysis generally outperform features derived from EFA in terms of cross validation classification accuracy. Finally, an application of the classification methods studied here was applied to fossils recovered from the deroofed Gladysvale External deposit (GVED), Gauteng Province, South Africa. Previous analyses of GVED identified a group of bovids as medium sized alcelaphines (Lacruz et al., 2002). Specifically, this study reclassified 32 unbroken, medium sized alcelaphines looking at shape and size-and-shape. The reclassifications increased the number of individuals and diversity of bovids recovered from the site. The results were used to generate a more precise paleoenvironmental reconstruction. [ABSTRACT FROM AUTHOR]

Abstract: Fossil bovids are widely recognized as valuable ecological indicators, useful for reconstructing paleoenvironments associated with the hominins of Africa. Taxonomic identification of bovid remains in the Plio-Pleistocene fossil deposits of South Africa is based predominantly on dental remains, usually isolated teeth. However, factors such as age and degree of occlusal attrition of teeth often render taxonomic identification difficult. In addition, teeth of closely related bovid taxa can be particularly difficult to diagnose at the species level. Given that closely related bovid species often have differing ecological requirements, imprecise identification of bovids recovered from fossil sites can have significant ramifications when reconstructing environments. This study tests a method for accurately identifying bovid teeth using Elliptical Fourier Function Analysis in order to standardize their identification. The occlusal surfaces of maxillary and mandibular molars of bovid teeth from twenty extant species were digitized and the quantified tooth forms (size and shape) were statistically compared to other closely related bovids. Results indicated that all upper and lower teeth classified correctly using discriminant function analysis ≥85% of the time, suggesting that occlusal surface form can reliably differentiate between closely related, morphologically similar bovids. This method was applied to a sample of fossil bovid teeth previously identified as “medium-sized alcelaphine” from Plovers Lake, Gauteng Province, South Africa. Precise taxonomic identification of these alcelaphines result in the earliest recorded presence of Alcelaphus buselaphus and Connochaetes gnou in Gauteng Province, as well as potentially the earliest documented co-occurrence of these taxa alongside Connochaetes taurinus and Damaliscus dorcas in South Africa. Revising the paleoenvironment reconstructed for Plovers Lake suggests that it was likely not much more densely wooded than the area today. This contradicts the paleoenvironment previously inferred for the site, suggesting that overreliance on rare and/or small-bodied taxa in the initial report on Plovers Lake overemphasized the extent of woodlands that were indicated. [Copyright &y& Elsevier]

Abstract: Plovers Lake is a dolomitic cave infill located approximately 45km northwest of Johannesburg in the Bloubank Valley, Gauteng Province, South Africa. Excavations between 2002–2004 revealed a rich and diverse fauna, a moderate-sized stone tool assemblage of Middle Stone Age (MSA) character, and human skeletal remains. Two principal depositional units are recognized: 1) a disturbed ex situ component that was likely displaced from 2) an otherwise relatively undisturbed in situ component from which the human skeletal material was recovered. The in situ depositional unit is bracketed by 2 flowstone layers, with U-series dates of 62.9 (±1.3)ka for the capping flowstone and 88.7 (±1.6)ka for the underlying flowstone. A single isochron ESR date of 75.6 (±5.6)ka corroborates the U-series dates. This paper presents an analysis of the mammalian, bird, and reptile faunas recovered from these two units. The two faunal assemblages show close correspondence in taphonomic, taxonomic, and ecological composition, supporting a common origin for both the ex situ and in situ components. Although human skeletal material, cut-marked bone, and stone tools have been recovered, these indications are too rare to consider Plovers Lake a human occupation site. Instead, a high abundance of carnivores, coprolites, and carnivore damaged bones point to brown hyenas as the principal, though not exclusive, bone accumulating agent. In the absence of a significant taphonomic bias relating to accumulating agent, Plovers Lake allows us to document an environment occupied by MSA humans, even if the humans were not resident in the cave itself. We reconstruct the paleoenvironment of Plovers Lake as predominantly grassland, though it was colder, moister, and more wooded than at present. Paleoclimatic conditions appear to have been as different from historic norms as those seen in several fossil localities in the Western Cape, pointing to greater environmental heterogeneity than has previously been documented for the region in the later Pleistocene. [Copyright &y& Elsevier]