DIVERSITY OF MARINE INVERTEBRATE COMMUNITIES IN THE NEOGENE OF THE DOMINICAN REPUBLIC

Exposures of Late Miocene and Early Pliocene marine strata in the Cibao Valley of the northern Dominican Republic preserve an abundance of invertebrate fossils (particularly mollusks and corals) and evidence of shifting paleoenvironments, making this study area ideal for exploring the relationships between habitat change and associated biotic responses over geological timescales. The Neogene fossil record of the Cibao Valley has been intensively studied and documented in a series of taxonomic monographs published in the Bulletins of American Paleontology. High-resolution spatio-temporal occurrence data derived from these monographs were assembled into a new species-level database in order to: quantify overall diversity patterns; determine whether communities exhibit stasis over time and across paleoenvironmental settings; and explore the relationships between biogeographic distributions and other species-level traits.

Here, we provide a new characterization of species-level diversity patterns for 119 species of mollusks (76 gastropods, 43 bivalves) and 28 coral species from this system. Published collection locality information from 18 monographs was combined into a single stratigraphic framework that spans the Miocene-Pliocene boundary (~6.5-3.5 Ma). This 3 Myr interval was divided into six time bins to characterize patterns of origination, extinction, and turnover in this system for the study species across five temporal boundaries, some of which correspond with shifts in the paleoenvironment. Analysis of the dataset reveals several interesting preliminary conclusions. First, gastropods, bivalves, and corals all show similar average species durations in this system (~1.2-1.3 Myr). Second, temporal diversity patterns appear to be controlled—at least in part—by the shifting environment, with deeper habitats often supporting a greater number of species than shallower habitats. Finally, overall rates of species origination equaled or exceeded rates of extinction across all but one of the five temporal boundaries, with mollusks showing higher rates of extinction relative to corals across a majority of the temporal boundaries.