A Late Pleistocene aridity and vegetation record from stable light isotope ratios of ostrich eggshell in Pinnacle Point
Even when interior regions experienced depopulation during the last glacial, the Southern Cape apparently remained attractive to Middle Stone hunter-gatherers for millennia. The region’s year-round rainfall and generally mesic conditions may have contributed to its attractiveness. Although seasonality and vegetation shifts have been observed in the nearby Crevice Cave stalagmite isotope record, indications for possible shifts in aridity are few. We apply oxygen (δ18O) and carbon (δ13C) isotope ratio analysis to a sequence of ostrich eggshell (OES) fragments from the PP5-6 site spanning a period from late OIS 5 to 3 to explore aridity changes. The OES δ13C and δ18O trends are broadly coherent but differ from the stalagmite. The δ18O data follow similar, but more marked, trends, suggesting a positive shift to more arid conditions during the latter stages of OIS4 compared to early OIS4 (Unit SADBS) and to today. The δ13C record is more muted, and indicaties that ostriches ingested mostly C3 vegetation although slightly higher proportions of C4 or CAM are reflected in moister Unit SADBS. Since the presence of 13C-enriched vegetation is indicated in the stalagmite record, the OES data suggest that ostriches found the taxa unattractive or they did not occur in the breeding season.
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A Late Pleistocene aridity and vegetation record from stable light isotope ratios of ostrich eggshell in Pinnacle Point. Julia Lee-Thorp, Kirsty Penkman, Curtis Marean. Presented at The 80th Annual Meeting of the Society for American Archaeology, San Francisco, California. 2015 ( tDAR id: 396828)
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min long: -18.809; min lat: -38.823 ; max long: 53.262; max lat: 38.823 ;