The fossil history of Grévy's zebra (Equus grevyi) in equatorial East Africa

Abstract

Aim Within the last several decades, Grévy's zebra (Equus grevyi) has undergone a massive reduction in geographical range and population size, largely as the result of human impacts. To place its recent decline in a deeper prehistoric context, and to understand the factors mediating its range and abundance over geological time frames, this study examines the fossil history of Grévy's zebra in equatorial East Africa.Location Equatorial East Africa.Methods Presence/absence data for ungulates recovered from fossil sites spanning the last c. 400,000 years in Kenya and Ethiopia were compiled from the literature and from previously unreported palaeontological sites. Associations between Grévy's zebra and other taxa were examined using principal coordinates analysis and non-random species pairs were identified using a Bayesian approach. Changes in rainfall were reconstructed using the average hypsodonty index of ungulate species from fossil assemblages.

Late Pleistocene age and archaeological context for the hominin calvaria from GvJm-22 (Lukenya Hill, Kenya)

“…The faunal assemblages from both occurrences indicate a dry, grassy, savanna environment. They are dominated by the extinct alcelaphine bovid Damaliscus hypsodon, with arid-adapted taxa, such as Grevy's zebra (Equus grevyi) and oryx (Oryx beisa), found well outside their historic ranges (21,27,28). Our analysis of the identified microfauna (number of identified specimens = 9) revises Gramly's analysis (20) and indicates a semiarid savanna environment (Gerbilliscus sp., Tachyoryctes cf.…”

Taxonomy and paleoecology of fossil Bovidae (Mammalia, Artiodactyla) from the Kibish Formation, southern Ethiopia: Implications for dietary change, biogeography, and the structure of the living bovid faunas of East Africa

“…For example, the record of Grevy's zebra (Equus greyvi) and beisa oryx (Oryx beisa) at Lukenya Hill and Lake Victoria is evidence for range expansions of both taxa during arid phases of the Pleistocene. Grevy's zebra and beisa oryx are united by adaptations to arid habitats and significantly co-occur in East African sites during the Pleistocene (Faith et al, 2013). The presence of Damaliscus hypsodon in the Kibish Formation provides evidence that this taxon was more widely distributed during the Middle to Late Pleistocene than previously recognized.…”

Variability in the Middle Stone Age of Eastern Africa

“…Modern distributions of a variety of plant and animal taxa consistently indicate eastward dispersal of forest taxa into and across the LVRM from heavily forested regions in central Africa during humid (i.e., interglacial) phases (e.g., Kingdon 1981;Rodgers, Owen, and Homewood 1982;Wronski and Hausdorf 2008). Conversely, LVRM MSA archaeological sites consistently include aridadapted fauna such as oryx (O. beisa) and Grévy's zebra (E. grevyi) that are characteristic of the SMCRE, suggesting westward dispersal during dry (i.e., glacial) conditions (Faith et al 2013;Tryon et al 2012). Hominin populations may well have followed a similar environmentally mediated pattern of range shifts.…”