Late Quaternary terrestrial vertebrates from Palawan Island, Philippines
Abstract Analysis of the Philippine fossil record is crucial in understanding the complex vertebrate distribution in this region and its relationship to Wallace's Line. The island of Palawan is of particular importance due to its westerly position within the Philippines, associating it more closely with islands on the Asian continental shelf, especially during the lowered sea levels of the Pleistocene. Palawan undoubtedly provided an important stepping stone for dispersing animals and humans into the Philippines. Humans first colonized Palawan ca. 40,000 year B.P. and likely had a dramatic impact on the distribution of indigenous floras and faunas. This study is the first to analyze the micro-vertebrate fossil assemblage of Palawan and to assess anthropogenic impact for the past 11,000 years. From May to July, 1997, we conducted five, small test excavations in Quezon Municipality, Palawan Province to locate productive sites for future, expanded excavations. We identified 753 terrestrial vertebrate bones (22 amphibian, 125 reptile, 35 bird, 571 mammal) resulting in 28 precisely identified species. Three species identified in the fossil assemblage are previously unrecorded from Palawan (scops-owl, Otus sp., swiftlet, Collocalia salangana , and shrew Crocidura sp.), while one, the Mountain White-eye ( Zosterops montanus ), lives only at high elevations today. Most species were recovered in a cultural site (Tarung-tung Cave) and are indicative of human consumption. Comparing these results to Borneo (a true continental island) provides insight into the affinity of the Palawan vertebrate fauna and may show the existence of a land bridge during the Pleistocene. The absence of large carnivores and primates from the Palawan fossil assemblage suggests a more insular affinity compared to Borneo. On the other hand, Palawan's fauna is relatively rich (with small carnivores and a pheasant) compared to truly oceanic islands. Future expanded excavations will focus on sampling vertebrates that lived during the first human colonization, as well as reconstructing the prehistoric ecology of the island.