A Jurassic squid fossil found in Bavaria, Germany in 2012 gives a rare insight into pterosaur hunting behaviours. The region was tropical at the time with lots of small islands in a shallow sea.
Not too much is known about ancient food chains, so this is a rare discovery indeed. The extinct Plesioteuthis squid had a pterosaur tooth embedded in its body when it died. This indicates that the squid was about to be a meal for a Rhamphorhynchus, the largest known pterosaur of its period when the predator’s tooth broke off. Whether this caused the death of the cephalopod or whether it died later of other causes is unknown.
Had the tooth not broken off, another scenario might have been that the relatively large squid could have pulled the pterosaur under water. The flying reptile was probably trying to catch the Plesioteuthis on the wing. The cephalopod either struggled hard or was maybe wrestled away by another predator who then also lost its prey. In any case, at some point, it sank to the oxygen-depleted bottom where it was preserved together with its predator’s tooth.
(Credit R. Hoffmann et al)
The tooth was identified by Jordan Bestwick, a paleobiologist working at the University of Leicester together with German and Swiss colleagues. They had already discounted a variety of other possible marine predators such as ichthyosaurs, pliosaurs, sharks and crocodiles when they finally discovered the tooth belonged to a Rhamphorhynchus, a flying reptile of the pterosaur order.
An examination under ultraviolet light also showed that the tooth was not merely resting on the Plesioteuthis’ remains but that it was properly embedded within the tissue showing the interaction between the two species.
Pterosaurs themselves were often prey of larger fish. We know this because of fossilised pterosaur remains within fish fossils. In 2012 an Aspidorhynchus, a large predatory fish was discovered with his jaws still wrapped around a Rhamphorynchus.
Rhamphorynchus fed primarily on smaller fish, as scales and fish bones have often been found in the throat and stomach of pterosaur remains. We can now add squid to their diet, who themselves fed on smaller fish. This reveals a four-level chain of predation around the Jurassic lagoon.
Many smaller pterosaurs, on the other hand, were filter feeders, much like modern flamingos. This was shown by examining coprolites, i.e. fossil droppings using synchrotron microtomography which works similarly to CT scanners. This technique revealed many microscopic food remains which can be explained through filter-feeding behaviour.
Both, pterosaurs and squids, however, were prey of ichthyosaurs as shown in remains found in an ichthyosaur graveyard in Chile in 2014.