Porifera and Cnidaria Diversity and Paleoecology in Pleistocene Epoch at Sangiran, Indonesia

The Kalibeng Formation of Sangiran Dome geological outcrop (Indonesia) in is an area where various fossils have been found, including ancient human fossils (Homo erectus), vertebrate fauna, and marine biota such as coral reefs. To date, the species diversity of fossil corals and sponges in Sangiran Dome and Indonesia, in general, is not widely known. The Sangiran stratigraphy is divided into several layers, with the lowest layer being the Kalibeng Formation, which was an ancient shallow sea, according to Brasseur et al. (2015). Further study can be conducted on the ancient corals and sponges’ in Sangiran to reveal the past environmental conditions, particularly during the Pleistocene period in the Sangiran Dome area. Fossilised corals and sponges with well-preserved conditions can serve as a basis for identifying various genera member of the Phylum Porifera and Cnidaria, using specific morphological characteristics for identification. The objective of this study is to determine the genus diversity also to define diagnostic characteristics, and habitat of corals and sponges’ fossils in the Plio-Pleistocene Period at Sangiran. The method used for identifying fossil samples was morphological comparison against type specimens and references. The results indicated that the identified corals and sponges were grouped into seven families that inhabits in the neritic zone. This study concludes that each coral genus (phylum Cnidaria) has distinctive corallite characteristics, while sponge genus (phylum Porifera) has distinctive spicules that are useful for identification.