This small rhamphorhynchid was once classified as a specimen of Rhamphorhynchus, but was reclassified in 2012 by David Hone and colleagues. Hone saw the holotype specimen in the Solnhofen Museum in 2007 when he attended the Flugsaurier conference on flying reptiles.
Hone observed that the specimen, a juvenile, while named under Rhamphorhynchus was actually starkly different from this more popular pterosaur. Thus the specimen was reevaluated and reclassified as the new genus Bellubrunnus rothgaengeri. The new paper was published in the journal PLOS by a team comprising Hone, Helmut Tischlinger, Erberhard Frey and colleagues.
Among the differences the team noticed was the lesser number of teeth in its jaws. It was still a fisherman of course, dipping into the shallow waters for its slippery prey just like Rhamphorhynchus. The animal's tail was also more flexible than its relatives, although whether this had something to do with the animal's age is unknown. Also because the holotype was a youngster, its skull was short and its eyes were very large in comparison to its body. Thus the adult animal might have had very different facial and bodily features.
Bellubrunnus also had a strange feature that set it apart from its relatives. The tips of its wings curved forward, although the exact reasons for this curvature are unknown. It is possible that this feature allowed for more maneuverability in the air while also stabilizing the soft tissue membranes of its wings. Unfortunately though, no such membranes had been uncovered on the holotype specimen.
The species name honors Monika Rothgaenger, a member of the team that uncovered the specimen and gave it to the museum. The genus name translates as "beautiful one from Brunn." Unlike Rhamphorhynchus, Bellubrunnus is not from Solnhofen. It is instead from the slightly older Brunn quarry. This quarry was 151 million years old, dating back to the Kimmeridgian Stage of the Late Jurassic.
Brunn lacks the massive array of wildlife that Solnhofen does but it was probably similar in composition. It too was a marine formation that preserved parts of the warm, shallow seas that covered great parts of Jurassic Europe.