中国科学院南京地质古生物研究所机构知识库

Bromalites are important indicators of dietary habits and potential predator-prey relationships, therefore, they largely enhance our comprehension of trophic interactions within marine ecosystems. A multi-disciplinary investigation was conducted on conodont-bearing bromalites discovered from the 'fish-bearing nodule layers' of the uppermost Lower Qinglong Formation (Longtan section, Nanjing, South China) that typifies one of the peri-Pangean distributed 'Triassic early Fish Faunas' (TEFF). The conodont species Scythogondolella milleri within some bromalites, visualized using X-ray microtomography, pinpoints the latest Smithian (Olenekian, Early Triassic) in age. These bromalites are described and classified into six distinct morphotypes: M1 (slender), M2 (raindrop-like), M3 (tadpole-like), M4 (kidney-like), M5 (folded), and M6 (plate-like). Morphological, inclusionbased, and geochemical analyses allow us to identify three morphotypes as coprolites with carbonaceous or phosphatic matrices. Conversely, the other three morphotypes, characterized by a scarcity of matrix material, are inferred to be regurgitalites. They were inferred to be likely produced by ammonoids, thylacocephalans, actinopterygians, and coelacanths. Subsequently, a trophically multileveled (at least 5 levels) end-Smithian marine ecosystem is reconstructed, in which multiple predators within higher trophic levels, including predatory invertebrates (e.g., ammonoids, crustaceans) and predatory fishes of different taxa, have heavy predation on conodonts. Under these conditions, conodonts, who are ecologically diverse, small-sized macrophagous predators or scavengers with a benthic or pelagic lifestyle, are posited to be an important food source for higher trophic level predators in this ecosystem. Furthermore, multiple predators of higher trophic levels preying on conodonts, alongside the consensus that conodonts have suffered modest losses during the end-Permian mass extinction (EPME) and dramatically re-diversified thereafter, implies that conodonts had most likely served as a key trophic linkage between pelagic and benthic food webs in the Early Triassic marine ecosystem, which was dominated by nektons, particularly fishes.