Bryozoan diversity in the Miocene of the Kutai Basin, East Kalimantan, Indonesia

Publication Type:Journal Article
Year of Publication:Submitted
Authors:E. Di Martino, Taylor, P. D., Johnson, K. G.
Keywords:abundance, growth-forms, preservation, Richness, substrates

Miocene bryozoans from the Indonesian Archipelago have been poorly investigated in the past. Several factors combine to explain their poor fossil record, including difficulties in locating good exposures in areas characterized by lush vegetation, dominance of inconspicuous encrusting species, and the adverse effects of diagenesis on fossil preservation. A large collection of samples from the Kutai Basin (East Kalimantan) made during the Marie Curie Initial Training Network ‘Throughflow’ has allowed new insights into the diversity of Miocene bryozoans in this region. The bryozoan assemblage as a whole consists of 123 species, which represents a remarkable increase in diversity compared to previous knowledge. Substrate availability appears to be the main factor controlling bryozoan distribution, the majority of encrusting species being associated with plate-like scleractinian corals. Collecting curves allow sampled sites to be divided into three groups characterized by high, medium and low species richness. The site of highest diversity is a mesophotic reef slope, environment influenced by strong input of terrigenous sediment. Ordination plots show no clear patterns of distribution among sites, with putatively endemic species accounting for most of the discrimination. A similar level of endemism and habitat heterogeneity characterizes modern, tropical bryozoan faunas. However, many more intermediate sites need to be sampled to achieve a fuller understanding of the true pattern of bryozoan species distribution in the Miocene of the Kutai Basin.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith