Although it would have looked superficially similar to the present day gars, it was not related to them, belonging to the Aspidorhynchiformes, an extinct group of fish noted for their elongated rostrums.

[2] Aspidorhynchus contains the following species:[3] A. antarcticus is known from Jurassic remains reworked into the Albian Whisky Bay Formation, and was the oldest neopterygian fossil discovered in Antarctica at the time.

In a 2012 description of WDC CSG 255, researchers proposed that the Rhamphorhynchus individual had just caught a Leptolepides while it was flying low over a body of water.

As the Leptolepides was travelling down its pharynx, a large Aspidorhynchus would have attacked from below the water, puncturing the left wing membrane of the Rhamphorhynchus with its sharp rostrum.

The encounter resulted in the death of both individuals, most likely because the two animals sank into an anoxic layer in the water body, depriving the fish of oxygen.