Balaenognathus: Beast of the Week

This week we'll be checking out a very unusual little pterosaur, Balaenognathus maeuseri! 

Balaenognathus was a pterosaur that lived in what is now Germany during the late Jurassic period, between 157 and 145 million years ago.  It was relatively small for a pterosaur, with a wingspan of a little under 4 feet (1.17 meters) from wingtip to wingtip. The genus name translates to "Bowhead whale jaw" after the modern Bowhead whale, one of many kinds of whale that sports structures called baleen in its mouth for filter-feeding on tiny animals.  When alive it is likely Balaenognathus fed on tiny animals in the water with the help of its specialized teeth.

Watercolor life reconstruction of Balaenognathus by Christopher DiPiazza.

Balaenognathus' most distinctive feature is its face, with a long, thin snout that curved slightly upwards toward the tip then flared out in an almost square shape at the very end.  The sides of both the upper and lower jaws were lined with hundreds of extremely thin teeth that were also hooked at the ends.  This appears to be an adaptation for capturing tiny creatures out of the water, much like the baleen of many modern whales.  Many birds, like flamingos and some ducks and geese, also sport structures similar to this in their mouths for filtering food from the water, but not to the extent that Balaenognathus had.  Even stranger is that Balaenognathus had a bony keel that extended from the roof of its mouth downward, which would have prevented it from closing its mouth completely.  This could also have something to do with a filter-feeding lifestyle, since the tips of the teeth could still overlap despite this feature.  

Flamingos and baleen whales, like the Bowhead whale, both independently evolved structures in their mouths to filter tiny animals for food.  Ctenochasmatids, like Balaenognathus, also independently evolved a similar feature for a similar feeding strategy.

Balaenognathus was a member of the family of pterosaurs, called ctenochasmatids, which are characterized by having relatively long necks and long skulls, lined with teeth.  Many members of this group appear to have had unique teeth for filter feeding on small prey in the water, which makes sense since all members of this group are mostly found in areas that would have had an abundance of water when they were alive.  What is interesting, however, is that no two members of this group have extremely similar kinds of filter-feeding teeth, implying they were eating similar prey in life, but probably were going about it in different ways with regards to their postures and movement.  Pterodaustro is an example of another kind of ctenochasmatid pterosaur that also sported baleen-like teeth, but in a different arrangement from Balaenognathus.

Photo of the fossilized skeleton of Baelenognathus.  Because of how complete and well-preserved it is, paleontologists were able to learn a lot about this unique pterosaur.

That's all for this week!  As always feel free to comment below or leave a request fora. future prehistoric beast to cover!

References

Martill, David M.; Frey, Eberhard; Tischlinger, Helmut; Mäuser, Matthias; Rivera-Sylva, Héctor E.; Vidovic, Steven U. (2023-01-21). "A new pterodactyloid pterosaur with a unique filter-feeding apparatus from the Late Jurassic of Germany".