Pterodaustro: Beast of the Week

This week we will be taking a look at a bizarre pterosaur.  Let's check out Pterodaustro gulnazui!

Pterodaustro was a pterosaur that lived in what is now Argentina, during the Cretaceous, about 105 million years ago.  Adults had a wingspan between eight and nine feet long and they would have likely eaten meat in the form of very small animals (more on that in a bit).  The genus name translates to "Wing from the South" and the species name honors paleontologist, Roman Gulnazu.

Pterodaustro life reconstruction I produced in watercolors.  Because this creature was likely a filter feeder it is often restored with pink coloration, like a modern flamingo, but many other animals that filter feed, like ducks, do not become this color and there is no reason to think Pterodaustro was more likely pink than not.  

Pterodaustro is a well-studied pterosaur.  It is known from multiple complete skeletons, including adults, juveniles, and even eggs with embryos still inside.   Thanks to this array of specimens paleontologists know a lot about this strange creature's life appearance and growth pattern.  

 By far the most striking feature about Pterodaustro is its face, particularly its mouth.  This pterosaur sported a long, thin beaklike mouth that gently curved upwards.  Growing up from the lower jaws were over a thousand bristle-like structures.  These structures, although hair-like, were actually highly specialized teeth.  It is thought that Pterodaustro used these modified teeth for filter feeding tiny creatures out of the water, much like a modern flamingo, or some whales do with baleen.  Pterodaustro also had very small, teeth on the upper jaws, possibly for processing its food after trapping it in the mouth with its unusual lower teeth.  A few Pterodaustro skeletons were found to have tiny rocks in their stomach cavities.  Many reptiles, including dinosaurs, lizards, and even modern birds, are known to swallow tiny rocks, called gastroliths, which help aid in crushing up food inside the stomach or crop once eaten.  Pterodaustro is the first example of a pterosaur that also did this.  Because of these rocks, it is implied that the food Pterodauestro was eating wasn't soft, so it was probably specifically filtering tiny crustaceans that sported exoskeletons that needed to be crushed and broken after capture.

Pterodaustro skeletal cast on display at the Museo Argentina de Ciencias Naturales in Burinos Aires, Argentina.

Pterodaustro had a long, thin neck and a relatively long torso for a pterosaur.  Its hind legs were proportionally short so it may not have been a very fast walker.  In order to get into the air to fly, takeoff also would have been relatively difficult because its short legs would have hindered it from launching very far from the ground.

The Pterodustro eggs on the fossil record are similar to other known pterosaur eggs in that they would have had somewhat soft shells, more similar to those of modern turtles than birds.  The babies would have only been a few inches long when first hatched and would have grown very quickly for their first two years of life until they became sexually mature.  They would have continued to grow at a slower pace for four to five more years.

That is all for this week!  As always please leave a comment below!

References

Chinsamy, A., Codorniú, L., and Chiappe, L. M. (2008). "Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui". Biology Letters. 4 (3): 282–285.

Codorniú, L., Chiappe, L.M., Arcucci, A., and Ortiz-Suarez, A. (2009). "First occurrence of gastroliths in Pterosauria (Early Cretaceous, Argentina)". XXIV Jornadas Argentinas de Paleontología de Vertebrados

John D. Currey (1999). "The design of mineralised hard tissues for their mechanical functions". Journal of Experimental Biology. 202 (23): 3285–3294.
Witton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.