In Depth
In the simplest terms, Aspidorhynchus was very similar to the modern day gar (a.k.a. garpike) fish that inhabit Central and North America as well as the Caribbean, and are noted for being very successful predators. The body is very long and slender with fairly small fins for the size but a fairly well-developed tail. Together the body has a form suited to relying more upon sudden acceleration towards a prey target, closing the distance before it was able to respond to the threat. The snout is elongated and thin, though it remains uncertain as to why it was this form. It may have been an aid in striking at fish either with a direct thrust or a side to side slashing motion like a modern day sword fish. A slashing motion would probably not kill a fish outright, but could potentially stun of grievously wound one so that it could not swim away. One of the most fascinating discoveries involving Aspidorhynchus involves the pterosaur Rhamphorhynchus. With the description published in 2012 by Frey and Tschlinger, specimen WDC CSG 255 is a slab that contains the remains of a Rhamphorhynchus with two fish, Aspidorhynchus and Leptolepides. The Leptolepides was found within the throat of the Rhamphorhynchus. The left wing of the Rhamphorhynchus is pulled back in an unusual posture, and it seems that in life the membrane of the left wing was speared by the long snout of the Aspidorhynchus.
The scenario is expected to have played out along the lines of a Rhamphorhynchus swooping in low to snatch a Leptolepides from the water. A roaming Aspidorhynchus then lunged towards the pterosaur, spearing its wing with the pointed snout. It is uncertain which creature the Aspidorhynchus was targeting, it may have actually been in the process of attacking the Leptolepides when Rhamphorhynchus just got in the way, or it may have even tried for Rhamphorhynchus as a target of opportunity. Either way it seems that with the pterosaurs wing wrapped around the fish’s snout the two sank down to a lower level of anoxic (oxygen depleted) water. Since pterosaurs couldn’t breathe underwater, the Rhamphorhynchus simply drowned, but the oxygen depleted water of the anoxic zone meant that the Aspidorhynchus would have suffocated and died before it could free itself from the pterosaurs wing membrane. The Leptolepides, still in the throat of the Rhamphorhynchus while this was happening would have had no chance of survival either. The same anoxic conditions that proved fatal to the Aspidorhynchus however were also responsible for the high level of preservation in the specimen.
This is not the first example of a fish vs pterosaur interaction. An example of the fish genus Saurichthys has been found with the remains of the pterosaur Preondactylus arranged in a bolus (a pellet of bones that would be spat out instead of digested) found in close association to Saurichthys. It is uncertain however if this was a case of active predation or scavenging.
Further Reading
- On some new genera and species of fossil fishes. - P. Egerton - 1854. - The Late Jurassic pterosaur Rhamphorhynchus, a frequent victim of the ganoid fish Aspidorhynchus? - E. Frey & H. Tischlinger - 2012.
