The study of fossil faunas in the Walanae Basin, Indonesia

The main purpose of my research was to reconstruct the morphology and phylogenetic history of Celebochoerus heekereni, an endemic pig species known from Pliocene fossil deposits in the Walanae Basin of Southwest Sulawesi, Indonesia. An important part of this research was to refine the age range of C. heekereni and to reconstruct its paleogeographic context on the basis of Southeast Asian plate tectonics and eustatic sea-level changes. This study has implications for the history of other animal species on Sulawesi, and for Southeast Asian biogeography generally. Associated fieldwork in the Walanae Basin included the description of fossil sites, the recording of stratigraphic sections, two excavations, and the collection of sediment samples for palaeoenvironmental reconstruction and dating. Associated analyses included qualitative and quantitative morphological analysis of C. heekereni cranial and dental remains collected either by previous researchers or during my fieldwork. Comparative data was also obtained on other extant and extinct pigs, including those of the before genus Sus and Babyrousa. This data was obtained from the published literature, as well as from my analyses of material held in the collections of the Indonesian Geological Survey Institute in Bandung, the Zoological Museum in Bogor, and the Australian National University in Canberra. Concerning phylogeny, C. heekereni shows a combination of primitive and advanced skull characteristics. Comparative analyses indicate that the ancestor of this species was most likely close to Palaeochoerus, a primitive suid genus known from the Lower Miocene of the Siwaliks in the Indian subcontinent, which gave rise to various Eurasian and African suid lineages, including extant warthogs. In contrast, dental morphology in C. heekereni underwent little change except for a reduction of the anterior premolars and an increase in the size of the upper canines. A synthesis of the available geological evidence indicates that since the Middle Eocene, no part of Sulawesi has been connected to the Asian mainland. As the ancestor of C. heekereni cannot have entered Sulawesi before the Lower Miocene, it had to have crossed a sea barrier. This could have occurred during the Middle Miocene, when deltaic progradation on the east coast of Borneo extended further east than at present, and crossing the Makassar Strait to reach Sulawesi would have been less difficult