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The Shungura Formation in the lower Omo River Valley, southern Ethiopia, has yielded an important paleontological and archeological record from the Pliocene and Pleistocene of eastern Africa. Fossils are common throughout the sequence and provide evidence of paleoenvironments and environmental change through time. This study developed discriminant function ecomorphology models that linked astragalus morphology to broadly defined habitat categories (open, light cover, heavy cover, forest, and wetlands) using modern bovids of known ecology. These models used seven variables suitable for use on fragmentary fossils and had overall classification success rates of >82%. Four hundred and one fossils were analyzed from Shungura Formation members B through G (3.4–1.9 million years ago). Analysis by member documented the full range of ecomorph categories, demonstrating that a wide range of habitats existed along the axis of the paleo-Omo River. Heavy cover ecomorphs, reflecting habitats such as woodland and heavy bushland, were the most common in the fossil sample. The trend of increasing open cover habitats from Members C through F suggested by other paleoenvironmental proxies was documented by the increase in open habitat ecomorphs during this interval. However, finer grained analysis demonstrated considerable variability in ecomorph frequencies over time, suggesting that substantial short-term variability is masked when grouping samples by member. The hominin genera Australopithecus , Homo , and Paranthropus are associated with a range of ecomorphs, indicating that all three genera were living in temporally variable and heterogeneous landscapes. Australopithecus finds were predominantly associated with lower frequencies of open habitat ecomorphs, and high frequencies of heavy cover ecomorphs, perhaps indicating a more woodland focus for this genus. [ABSTRACT FROM AUTHOR]

Abstract: The habitat preferences of fauna found at palaeontological and archaeological sites can be used to investigate ancient environments and hominin habitat preferences. Here we present a discriminant function model linking astragalus morphology to four broadly defined habitat categories (open, light cover, heavy cover, and closed) using modern bovids of known ecology. Twenty-four measurements were taken on a sample of 286 astragali from 36 extant African antelope species. These measurements were used to generate ratios reflecting shape. An 11 variable discriminant function model was developed that had high classification success rates for complete astragali. Resubstitution analysis, jackknife analysis, and the classification of several “test samples” of specimens suggest that the predictive accuracy of this model is around 87%. The total classification success rates of 87% (jackknifed) or 93% (resubstitution) are considerably higher than those derived in another study of bovid astragalus ecomorphology (67%; [DeGusta, D., Vrba, E.S., 2003. A method for inferring palaeohabitats from the functional morphology of bovid astragali. J. Archaeol. Sci. 30, 1009–1022]) that used a more limited measurement scheme and a smaller sample of bovids than the present study. Different approaches to operationalizing ecomorphic analyses are considered in order to best extract accurate palaeoenvironmental information from palaeontological and archaeological datasets. [Copyright &y& Elsevier]

Abstract: The middle Pleistocene fossil mammal assemblage from Lainyamok in the southern Kenya rift has previously been considered the oldest (330–392ka) African mammal community consisting entirely of extant species, with the dominant bovid tentatively attributed to the southern African blesbok (Damaliscus cf. dorcas). We show that the blesbok-like fossils from Lainyamok belong to an extinct species, described here as Damaliscus hypsodon sp. nov. The D. hypsodon hypodigm includes the previously unnamed small alcelaphine material known from late Pleistocene sites elsewhere in Kenya and Tanzania. Its dental anatomy, together with an ecomorphological analysis of its postcrania, indicates that D. hypsodon grazed in open and arid grassland environments. Although Lainyamok is no longer represented entirely by extant species, the absence of species common earlier in the middle Pleistocene of East Africa suggests substantial faunal turnover between 500 and 400ka. Damaliscus hypsodon persisted in East Africa until the end of the Pleistocene and its extinction can be attributed to a loss of arid grassland environments at the onset of the Holocene. The fossil evidence from southern Kenya suggests that the development of the taxonomically modern large mammal community was a long-term process characterized by the extinction of grazing specialists, with marked turnover occurring between ~500 and 400ka and near the end of the Pleistocene. [Copyright &y& Elsevier]

Summary The fossil record provides tangible, historical evidence for the mode and operation of evolution across deep time. Striking patterns of convergence are some of the strongest examples of these operations, whereby, over time, similar environmental and/or behavioral pressures precipitate similarity in form and function between disparately related taxa. Here we present fossil evidence for an unexpected convergence between gregarious plant-eating mammals and dinosaurs. Recent excavations of Late Pleistocene deposits on Rusinga Island, Kenya, have uncovered a catastrophic assemblage of the wildebeest-like bovid Rusingoryx atopocranion . Previously known from fragmentary material, these new specimens reveal large, hollow, osseous nasal crests: a craniofacial novelty for mammals that is remarkably comparable to the nasal crests of lambeosaurine hadrosaur dinosaurs. Using adult and juvenile material from this assemblage, as well as computed tomographic imaging, we investigate this convergence from morphological, developmental, functional, and paleoenvironmental perspectives. Our detailed analyses reveal broad parallels between R. atopocranion and basal Lambeosaurinae, suggesting that osseous nasal crests may require a highly specific combination of ontogeny, evolution, and environmental pressures in order to develop. [ABSTRACT FROM AUTHOR]