22-11 You are what you eat: evaluating fish tooth morphology as a proxy for food web dynamics in marine sediments

Session: Working Up an Apatite: Teeth as Paleo -Ecological and -Climatological Archives

Presenting Author:

Authors:

Abstract:

Ichthyoliths – isolated microfossil fish teeth and shark scales – are the most numerically abundant vertebrate fossils on the planet and their dissolution-resistant bioapatite composition allows them to be preserved in nearly all marine sediment types. As such, ichthyoliths harbor considerable potential to reveal high-precision records of fish and shark evolution, and the relationship with climatic and environmental changes throughout Earth’s history. Fish and sharks are an integral part of the marine ecosystem, and the abundance and diversity of fish present in a particular location is dependent on a functional marine ecosystem which passes fixed carbon from primary producing phytoplankton, through the food web to these upper-level vertebrate consumers. The vast majority of the marine food web lacks hard parts and is therefore effectively invisible in the fossil record. However, teeth are the primary way that fish interface with their prey, and thus the morphology of teeth preserved in a sedimentary system may provide insights into both the fish community, as well as the zooplankton prey which sustained them. While tetrapod tooth morphology is well constrained with respect to diet in most groups, fish do not have similar tooth morphology-diet relationships to their terrestrial relatives. Here we explore the non-intuitive relationships between fish tooth morphology and target prey by building a comprehensive dataset of detailed tooth morphology and diet for over 800 species of marine and freshwater fish from over 300 taxonomic families across the fish tree of life, representing all extant ecological guilds and fish lineages. We find that tooth morphology has some relation to diet, however the relationship differs between taxonomic lineages. These results demonstrate that ichthyoliths have the potential to shed light not only on fish evolutionary history, but on their ever-changing ecological roles in marine systems, and on the non-fossilized structure of zooplankton communities that underpin the marine consumer populations of oceans past and present.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10998

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.