THE ISOTOPIC ECOLOGY OF LATE PLEISTOCENE MAMMALS IN NORTH-AMERICA - PART 1 - FLORIDA

Mammoths and mastodons are common in Pleistocene deposits, yet these p roboscideans and many other animals disappeared suddenly approximate t o 10,000 years ago. In this study, we reconstruct the diets of probosc ideans and associated mammals through isotopic analysis of carbonate i n tooth enamel apatite in order to test nutritional hypotheses for lat e Pleistocene extinction. We analyzed specimens from six sites in Flor ida, ranging from full glacial (> 21,000 BP) to late glacial (14,750 t o 10,000 BP) age. The oxygen isotope composition of mammalian apatite covaries with meteoric water composition, which in turn varies with cl imate. Consequently, oxygen isotope analysis can be used to assess the potential for time-averaging or mixing of specimens from different ge ographic regions within fossil assemblages. The carbon isotope composi tion of an herbivore is controlled by the isotopic composition of the plants that it ingests. Carbon isotope analysis reveals that mastodons ate chiefly C-3 plants, presumably trees, shrubs and herbs, whereas m ammoths consumed chiefly C-4 grass. Several nutritional hypotheses for late Pleistocene extinction entail the assumption that extinct taxa h ad specialized diets. The resource partitioning and focused feeding pr eferences of Florida's proboscideans corroborate this assumption, but they do not, in themselves, prove that nutritional stress was the caus e of the late Pleistocene extinction. (C) 1998 Elsevier Science B.V. A ll rights reserved.