Reconstruction of the Relative Abundance of Fossil Shark Teeth in the Gatun Formation (Late Miocene), Panama.

This project focuses on the paleoecological characterization of the San Judas locality within the Gatun Formation, Middle Gatun (Late Miocene, 7.88 - 10.28 Ma (based on updates from GTS2020) on Panama’s Caribbean coast. The study aims to analyze taxonomic composition, relative abundance, diversity indices, and methodological biases associated with collecting fossil shark teeth. Through fieldwork conducted in 2025, including surface sampling across three expeditions with 53 participants, specimens were recovered, identified, and compared to previous studies from the region using more systematic techniques such as screenwashing and handpicking. Laboratory classification of 70 teeth allowed genera and species identifications using reference guides from STRI and the Florida Museum of Natural History. Genera identified include †Otodus, Carcharhinus, Negaprion, †Hemipristis, and Sphyrna. This study uses declared effort and diversity metrics to evaluate sampling completeness through rarefaction and contrasts fossil data with modern shark distributions. The results contribute to the understanding of the Late Miocene neritic shark ecosystems in the region and highlight the value of replicable, effort-reported surface collection methods for community science and paleoecological research in the Gatun Basin.