323-3 Peering into the protoconch: a survey of Nassarius in the Neogene Caribbean

Session: Paleontology, Diversity, Extinction, Origination (Posters)

Poster Booth No.: 123

Presenting Author:

Carmi Milagros Thompson

Authors:

Thompson, Carmi Milagros¹, Leonard-Pingel, Jill², O'Dea, Aaron³, Finnegan, Seth⁴, Klompmaker, Adiël A.⁵r> (1) The Ohio State University, Columbus, OH, USA, (2) The Ohio State University, Newark, OH, , (3) Smithsonian Tropical Research Institute, Panama City, Panama; Sistema Nacional de Investigación, Secretaría Nacional de Ciencia, Tecnología e Innovación, Panamá, Panama, (4) University of California, Berkeley, CA, ; Smithsonian Tropical Research Institute, Panama, (5) Department of Museum Research and Collections, UA Museums, University of Alabama, Tuscaloosa, Alabama, ,

Abstract:

The larval mode of individual gastropods can be inferred from shape, size, and morphological characteristics of the protoconch, or larval shell. The size is tied to larval mode, which is often related to primary productivity. In the Neogene southwestern Caribbean, environmental change initiated by the formation of the Isthmus of Panama impacted oceanographic conditions (warmer temperatures, higher salinity, and a decrease in productivity). Previous work on gastropod ecology shows that there are documented broad-scale decreases in predatory gastropods during this time. However, we still do not have a complete picture of how decreases in primary productivity may have impacted gastropod communities. Beyond changes in trophic structure, gastropod communities may have experienced other ecological or evolutionary changes driven by changes in primary productivity. This protoconch study continues to provide additional insight into individuals that live in the communities of this changing ecosystem.

Here, we look at the protoconchs of Nassarius (family: Nassariidae). This genus was selected because it is abundant across samples collected from fossil localities in the Isthmus and because of its trophic position. We anticipate that larval mode of this genus will switch developmental strategy from lecithotrophic to direct as the Isthmus closes. For our preliminary survey, we have collected some measurements of protoconchs of Nassarius using an AXIO Zoom.V16 microscope and Zen core 3.16 software. Magnification varied from 100x to 250x, depending on the size of protoconch of the organism (and overall size of the shell). Specimens were imaged on a dark background for contrast. Following collection of images, FIJI was used to extract measurements of diameter and number of whorls, which can be used to infer larval mode. These measurements will be used to explore our hypothesis.

Peering into the protoconch: a survey of Nassarius in the Neogene Caribbean

Description

Session Format: Poster

Presentation Date: 10/14/2026

Presentation Room: CCC, Hall F

Poster Booth No.: 123

Author Availability: 9:00 to 11:00 a.m.

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