New Findings at Andrahomana Cave, Southeastern Madagascar

A remote eolianite cave and sinkhole complex on the southeast coast of Madagascar has played a major role in the history of paleontology in Madagascar. Andrahomana Cave has yielded a rich fossil record of the extinct megafauna. Expeditions in 2000 and 2003 produced a wealth of new material and provided the first systematic information concerning the genesis, stratigraphy, and taphonomy of the site. Recovered bones of one of the most poorly understood extinct large lemurs, Hadropithecus stenognathus, include many skeletal elements previously unknown. Radiocarbon dates show that the site has sampled this disappeared fauna in the midto-late Holocene, but that bone-bearing layers are stratigraphically mixed, probably owing to the effects of reworking of the sediments by extreme marine events. The diverse biota recovered contains elements of both eastern rain forest and southwestern arid bushland, reflecting the cave’s position in the zone of transition between wet and dry biomes. Bones of two unusual small mammals add to the previously long faunal list for the site: 1) the first fossil evidence for Macrotarsomys petteri, a large-bodied endemic nesomyid rodent previously known only from a single modern specimen; and 2) the type specimen and additional material of a newly described extinct shrew-tenrec (Microgale macpheei). Evidence for prehistoric and colonial-era humans includes artifacts, hearth deposits, and remains of human domesticates and other introduced species. Although previously protected by its extreme isolation, the unique site is vulnerable to exploitation. An incipient tourist industry is likely to bring more people to the cave, and there is currently no form of protection afforded to the site.