Meeting Abstract
Following extreme climatic warming events, the Eocene epoch saw a shift toward modern marine faunas characterized by the prevalence of acanthomorph teleosts and a trophic network crowned by carcharhiniform sharks. However, the reliance on isolated teeth has limited the systematic and paleoecological understanding of the early Cenozoic sharks, and predator-prey dynamics in the Eocene marine food web remain poorly understood.
We report an exceptionally preserved fossil school shark (Galeorhinus cuvieri) from Pesciara di Bolca, Italy — a lagerstätte documenting a coral reef fish assemblage near the end of the Early Eocene Climatic Optimum. In addition to the spectacular preservation of soft tissues including the brain, muscles, and claspers, this male juvenile shark has stomach contents clearly identifiable as a sphyraenid acanthomorph (barracuda). This association provides evidence that a predator-prey relationship between Galeorhinus and Sphyraena in the modern coral reefs has an Eocene root.
A growth curve of the living species of Galeorhinus fitted to G. cuvieri indicates that all six specimens of G. cuvieri from the lagoonal deposits of Bolca represent juveniles younger than 5 years in age. This biased representation is consistent with the living species of Galeorhinus in which juveniles occupy ‘nursery’ habitat.
We suggest that, following the early Cenozoic thermal events, modern trophic relationships between acanthomorph fishes and carcharhiniform sharks developed in the recovering scleractinian coral reef communities. Predator-prey relationships across multiple trophic levels likely played a role in shaping the modern coral reef communities.
