The Fossil Herpetofauna of the Pindai Caves, New Caledonia: With Implications for the Effect of Human Habitation on Island Faunas.

摘要

Excavations in the Pindai Caves of New Caledonia, a large island in the South Pacific, have yielded a fossil assemblage rich in squamate remains. The fossiliferous deposits at Pindai Caves are restricted to six caves along the northwest coast of the Grand Terre. The fossils examined in this study are from four of the caves and are derived from degraded Barn Owl ( Tyto alba) pellets. Radiocarbon dating suggests dates of 1640+/-40-4743+/-44YBP spanning the deposits. As humans are thought to have reached New Caledonia about 2800YBP, this assemblage provided a unique opportunity to examine the effect human arrival had on the herpetofauna of New Caledonia. Approximately 25,000 squamate fossils, comprising chiefly maxillae, premaxillae, prefrontals, frontals, parietals, quadrates, dentaries, surangulars, and vertebrae were recovered from Pindai. All are attributable to Diplodactylidae, Varanidae, and Scincidae, with the diplodactylid gecko species Rhacodactylus trachyrhynchus most common. Similar to the New Caledonian avifauna, which experienced elevated extinction rates upon the arrival of humans, the Pindai fossil herpetofauna includes at least three extinct or extirpated species. Additionally, R. trachyrhynchus is rare in the region today, being known from only a single recent specimen, and gekkonid geckos, which are widespread in coastal New Caledonia today, are lacking in our samples. Gekkonids may have been introduced as recently as 237 years ago with the arrival of Europeans, but the arrival of Melanesians nearly 3000 years ago may have precipitated ecological changes that changed patterns of lizard abundance if not species composition. However, in this study, no statistically significant changes in the composition or diversity of the herpetofauna were detected immediately following the initial colonization of the Pindai region.