Abstract
BackgroundFollowing extreme climatic warming events, Eocene Lagerstätten document aquatic and terrestrial vertebrate faunas surprisingly similar to modern counterparts. This transition in marine systems is best documented in the earliest teleost-dominated coral reef assemblage of Pesciara di Bolca, northern Italy, from near the end of the Eocene Climatic Optimum. Its rich fauna shows similarities with that of the modern Great Barrier Reef in niche exploitation by and morphological disparity among teleost primary consumers. However, such paleoecological understanding has not transcended trophic levels above primary consumers, particularly in carcharhiniform sharks.ResultsWe report an exceptionally preserved fossil school shark (Galeorhinus cuvieri) from Pesciara di Bolca. In addition to the spectacular preservation of soft tissues, including 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 roots in the Eocene. A growth curve of the living species of Galeorhinus fitted to G. cuvieri suggests that all specimens of G. cuvieri from the lagoonal deposits of Bolca represent sexually and somatically immature juveniles.ConclusionThe modern trophic association between higher-degree consumers (Galeorhinus and Sphyraena) has a counterpart in the Eocene Bolca, just as Bolca and the Great Barrier Reef show parallels among teleost primary consumers. Given the age of Bolca, trophic networks among consumers observed in modern coral reefs arose by the exit from the Climatic Optimum. The biased representation of juveniles suggests that the Bolca Lagerstätte served as a nursery habitat for G. cuvieri. Ultraviolet photography may be useful in probing for exceptional soft tissue preservation before common acid preparation methods.Electronic supplementary materialThe online version of this article (doi:10.1186/s40851-016-0045-4) contains supplementary material, which is available to authorized users.
Highlights
Fossil record documents profound changes in both marine and terrestrial ecosystems across the PaleoceneEocene Thermal Maxima (55.8 and 53.7 million years ago) [1,2,3,4]
Pesciara di Bolca Konservat–Lagerstätte from northern Italy occupies a special place in understanding the shift toward modern marine ecosystems
Documenting the earliest occurrences of many acanthomorph lineages, the Bolca fishes represent the earliest of clearly defined coral reef fish assemblages [6, 15,16,17]. This assemblage resembles modern coral reef faunas in its remarkably high functional diversity of primary consumers, which in large part was facilitated by significant increase in morphological disparities among acanthomorph teleosts during the Paleocene-Eocene interval [3, 18,19,20,21]
Summary
Fossil record documents profound changes in both marine and terrestrial ecosystems across the PaleoceneEocene Thermal Maxima (55.8 and 53.7 million years ago) [1,2,3,4]. Pesciara di Bolca Konservat–Lagerstätte from northern Italy occupies a special place in understanding the shift toward modern marine ecosystems This late Ypresian Lagerstätte with more than 250 vertebrate species (approximately 90 families) [5,6,7] coincides chronologically with the latest phase of the Early Eocene Climatic. Following extreme climatic warming events, Eocene Lagerstätten document aquatic and terrestrial vertebrate faunas surprisingly similar to modern counterparts This transition in marine systems is best documented in the earliest teleost-dominated coral reef assemblage of Pesciara di Bolca, northern Italy, from near the end of the Eocene Climatic Optimum. Such paleoecological understanding has not transcended trophic levels above primary consumers, in carcharhiniform sharks
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