A diverse assemblage of corals from the Late Oligocene of eastern Sabah, Borneo: pre-Miocene origins of the Indo-West Pacific marine biodiversity hotspot.

Abstract

Abstract:
A diverse collection of corals has been collected from Sabah in Malaysian Borneo. The fossil localities studied have been accurately dated using a combination of nannofossils, larger benthic foraminifera and strontium isotopes, placing them within the mid to Late Oligocene, where previously they were thought to be of Miocene age. The corals have been taxonomically identified to genus-level and placed into likely species groups within each genus, descriptions and photographs of the majority of species are presented here. There are approximately 55 genera present in the collection, and about 100 species. The diversity of this region has been analysed compositional groupings of genera at each locality have been identified. Sampling methods have been identified as important in fossil diversity analyses. This fauna has been compared to other Cenozoic coral faunas from the Indo-West Pacific (IWP) and also from the Mediterranean and Caribbean. The origins of high diversity in the Indo-West Pacific region can now be said to have occurred at least as far back as the late Oligocene, but the region did not become the global hotspot for scleractinian diversity until the Miocene. The study area contains a majority of extant, zooxanthellate genera, suggesting that the Indo-West Pacific region may be a “centre of survival” (Hoeksema, 2007; Wilson and Rosen, 1998) for zooxanthellate corals.