Temnodontosaurus bromalites from the Lower Jurassic of Germany: hunting, digestive taphonomy and prey preferences in a macropredatory ichthyosaur

Fossilized food items found in or passed through the digestive tract of an animal (bromalites) offer a window into the dietary habits and ecological role of the producer taxon. Bromalites have been documented from several small to mid‐sized parvipelvian ichthyosaurian species from the Lower Jurassic, but are seldom documented for the largest taxa. Temnodontosaurus trigonodon is an iconic Lower Jurassic macropredator, but the few bromalites attributed to this taxon have never been cumulatively reappraised. Here we provide a detailed revision of three specimens from the Toarcian Posidonienschiefer Formation interpreted as bromalites attributable to T. trigonodon . The first specimen is represented by a coiled‐up juvenile Stenopterygius skeleton, interpreted as a regurgitalite. Similarly, a second clustered mass of fractured and etched skeletal elements of an adult Stenopterygius has been also attributed to a regurgitalite. The peculiar taphonomy of these specimens supports this interpretation, and T. trigonodon is recognized as the only feasible producer of the gastric pellets. Last, a T. trigonodon skeleton preserving a large area of stomach contents (consumulite) composed of coleoid remains and neonatal ichthyosaur bones is re‐described here. Different stages of preservation are recognized in the ingested vertebrae, suggesting separate timing of prey ingestion. A detailed microstructural and chemical characterization of some bone fragments extracted from the consumulite highlights the action of gastric secretions on the ingested skeletal elements. The three surveyed bromalites support the interpretation of T. trigonodon as a nekton macropredator, but also highlight a specific targeting of neonatal to juvenile Stenopterygius individuals as prey items.