Mammal Evolution and Ecology 

 

Analysis of vertebrate remains from Plio-Pleistocene deposits across southern and East Africa (James Brink, Liora Kolska Horwitz)

This research includes analysis of assemblages from sites such as Wonderwerk Cave (involving the identification of vertebrate remains from the old and new excavations covering a geological time period from c. 1.8 Ma up to the Holocene), Drimolen Cave, Bolt's Farm, and Kilombe Acheulean site, central Rift Valley
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Does C4 grass limit the diversity of intermediate-feeding ruminants in Africa? (Daryl Codron, James Brink)

The browser/grazer dichotomy of ungulate herbivores shows an uneven distribution at global scales, with African taxa being primarily specialized browsers or grazers, whereas >50% of taxa from other parts of the world are more generalized mixed-feeders. Metabolic and mechanical costs of processing C4 foods (the dominant grass type in African savannas) is hypothesized to be the major constraint limiting African ungulates to one of two specific dietary niches. African grazers evolved extreme morphophysiological adaptations to enable occupation of the C4 dietary niche, and browsers cannot competitively invade this niche space. Elsewhere, especially in temperate zones where grasses are predominantly C3, the lack of extreme specializations means that ungulates are less constrained to one specific dietary niche. This research investigates relationships between craniodental specializations, gastrointestinal anatomy, and related physiological parameters with species' natural diets, and compares these relationships between African and non-African ungulate faunas. It is predicted that stronger relationships exist in the African component, reflecting their more stringent dietary constraints. Similarly, we are investigating relationships between craniodental and dietary (i.e. stable isotope) changes in the South African ungulate fossil record, where we expect temporal shifts in morphology within lineages to be accompanied by temporal diet shifts.


Early & Middle Pleistocene evolution of large mammal faunas and modern landscapes in southern Africa (James Brink, Daryl Codron, Lloyd Rossouw)

This research includes further excavations and study of the Cornelia-Uitzoek fossil vertebrate locality; the exploration and investigation of the Modder River terrace deposits, including Erfkroon; and a micromorphological study of the fossil-bearing deposits at Florisbad and Cornelia-Uitzoek.


The evolution of enamel volume and hypsodonty in grazing ungulates (James Brink, Daryl Codron)

This research is being carried out over two levels. The first is specific, for which we are studying specialization in the dietary niche of the extinct grazing springbok Antidorcas bondi (Mammalia, Bovidae), as seen in a temporal increase in the enamel volume of third molars. In a more general sense, we are investigating divergent evolutionary routes to grazing in ruminants based on structural adaptation as seen in enamel volume and hypsodonty in Alcelaphini, Hippotragini and Reduncini. Both investigations make use of the digital extraction of tooth enamel from lower dentitions by means of micro-ct scanning at Necsa. Further, correlations with changes in stable isotope composition (variation across taxa, but also spatio-temporally within species) are used to test hypotheses about the functional significance of dental traits.