The remains of a lizard in the German specimen's thoracic cavity show that "Compsognathus" preyed on small vertebrates. Marsh, who examined the specimen in 1881, thought that this small skeleton inside "Compsognathus" belly was an embryo, but in 1903, Franz Nopcsa concluded that it was a lizard. Ostrom identified the remains as belonging to a lizard of the genus "Bavarisaurus", which he concluded was a fast and agile runner owing to its long tail and limb proportions. This in turn led to the conclusion that its predators, "Compsognathus", must have had sharp vision and the ability to rapidly accelerate and outrun the lizard. The "Bavarisaurus" is in a single piece, indicating that the "Compsognathus" must have swallowed its prey whole. The French specimen's gastric contents consist of unidentified lizards or sphenodontids.