Patterns in Amino Acid Delta 15N Values of Lemurs Are Inconsistent with Aridity Driving Megafaunal Extinction in Southwestern Madagascar

Summary

Early human colonists of Madagascar encountered a diverse endemic fauna during the late Holocene that included elephant birds, pygmy hippos, and giant lemurs. All fauna >10 kg went extinct in the past 1,000-2,000 years. Direct human predation and anthropogenic landscape change help explain aspects of the extinction pattern. Increasing aridity may have also played a role in some regions, but its contribution remains controversial. We track changes in aridity during the past 4,000 years in southwestern Madagascar using nitrogen isotope (delta 15N) values of individual amino acids preserved in bones from extinct Pachylemur and extant Propithecus from two subfossil sites: Tsirave and Taolambiby. We use the delta 15N values of source amino acids as a proxy for aridity and the spacing of delta 15N values between source and trophic amino acids to quantify the trophic position of these lemurs. Despite paleohydrological evidence for a lowering water table and paleoecological evidence for the expansion of relatively arid savanna between 4,000 and 1,000 years ago, the isotope data indicate that extinct lemurs did not live in increasingly arid habitats. Thus, aridity cannot be the primary driver of lemur extinction in southwestern Madagascar.

This Resource is Part of the Following Collections

• Society for American Archaeology 82nd Annual Meeting, Vancouver, BC (2017)

Keywords

Spatial Coverage

Record Identifiers

Abstract Id(s): 16819