Radiocarbon dating and stable isotopes analyses of Caiman latirostris (Daudin, 1801) (Crocodylia, Alligatoridae) from the late Pleistocene of Northeastern Brazil, with comments on spatial distribution of the species

摘要

Caiman latirostris is a crocodilian reptile widely distributed in South America. The fossil records for this species are limited in the continent and radiocarbon dating, plus isotope analysis, has not been performed to the existing records, which prevent accurate paleoecological reconstructions. Thus, the present study aimed to record the occurrence of a fossil of C. latirostris in Sergipe state, Northeastern Brazil, providing the first data of radiocarbon dating and stable isotopes (δ~(13)C and δ~(18)O) for this species, as well as maps of the potential distribution for the present time and for the Last Glacial Maximum (21 ka). Our results indicate that the analyzed specimen occurred in Sergipe, Brazil, between 11,068-11,211 cal BP (9680 ± 30 BP), and fed on mixed-feeder animals (δ~(13)C = -3.00‰), possibly insects, shrimp, snail, fish, and birds. It appears that its body temperature was ～26 ℃, similar to the extant crocodilian species Crocodylus niloticus, indicating that the species lived in the nearby rivers, or in tanks (ancient lagoons). A map displays the current distribution, while the map for 21 ka indicates a restricted distribution for this species in South America, perhaps caused by the dry and cold climate in the Last Glacial Maximum, which affected the distribution of water sources for this organism.