ANTECEDENTS OF THE MODERN TROPICAL AMERICAN CONE SNAIL FAUNA: PHYLOGENETIC DIVERSITY AND BIOGEOGRAPHICAL HISTORY OF LATE MIOCENE TO PLIO-PLEISTOCENE CONIDAE IN THE CONTEXT OF MAJOR REGIONAL ENVIRONMENTAL CHANGE

Recent advances in molecular systematics have greatly clarified the phylogenetic relationships of extant cone snail species, which comprise one of the most diverse clades of marine invertebrates (Conidae). This robust phylogenetic framework also sheds light on the combinations of shell features that characterize individual clades, allowing extinct taxa known only from the fossil record to be incorporated into the phylogenetic context of extant Conidae. Incorporation of ancient species into phylogenetic hypotheses of extant taxa provides minimum age estimates for the clades to which the extinct taxa are assigned, thus adding new temporal information about the pace and history of cone snail evolution.

The phylogenetic positions of Neogene tropical American cone snail species from the southeastern United States (Plio-Pleistocene), Dominican Republic (Late Miocene and Early Pliocene), and Panama (Late Miocene) are predicted based on multiple shell features, including preserved coloration patterns revealed using ultraviolet light. Special attention is focused on fossils from the Late Miocene Gatun Fm. of Panama that were collected in July 2015 as part of the National Science Foundation-supported Great American Biotic Interchange-Research Experiences for Teachers (GABI-RET) project.

Preliminary results demonstrate that: 1) Neogene tropical American cone snails are phylogenetically diverse; 2) they have a complex regional biogeographic history; and 3) some extant lineages diverged earlier than has been suggested by previously published work. These results are considered within the context of major environmental changes associated with the Neogene closure of the Central American Seaway.