The Small Mammals of Callao Cave: Preliminary Taxonomic Identifications and Insights into Environments from the Late Pleistocene Until the Late Holocene

Patricia S. Cabrera1*, Juan C. Rofes1,2, Janine Ochoa1, Lawrence Heaney3, and Armand Salvador B. Mijares1

The Callao Cave in Peñablanca, Cagayan, Philippines has a record of human presence, activities, and faunal remains in the vicinity from three discrete phases that span the Late Pleistocene (ca. 134,000 BP and ca. 28,000 cal. BP) until the Late Holocene (ca. 3600 cal. BP). Remains of the extinct Homo luzonensis and endemic giant cloud rats (Muridae: Phloeomyini) were discovered in the cave, highlighting the potential of Callao Cave for studying human evolution and past biodiversity. Tropical environments are increasingly coming into focus in contextualizing the evolution of humans in Island Southeast Asia. As such, the inference of past environmental conditions using small mammals as proxies is our primary objective. Preliminary taxonomic identifications of the Callao Cave 2020 small mammal assemblage to the lowest possible level and insights into the environments they potentially represent will be discussed. Across the sequence, the assemblage represents three mammalian orders, specifically bats (six families), rodents (three tribes), and shrews (one genus). This is an ongoing research project from which human interactions with and impacts on the environment can later be explored. The lowland forest of Peñablanca hosts both native and non-native mammals, the latter of which are believed to have arrived in Luzon during the Late Holocene, in contrast to millions of years for the former; the current archaeological evidence hints at the possibility that the extinction of certain taxa may have coincided with the intensification of anthropogenic activities and the arrival of non-native species.