Helveticosaurus: Beast of the Week

This week we will be checking out an unusual reptile with anatomy that continues to stump paleontologists.  Let's check out Helveticosaurus zollingeri!

Helveticosaurus was a marine reptile that lived during the Triassic period, about 242 million years ago, in what is now Switzerland.  From snout to tail it measured a little over six feet long.  The genus name translates to “Swiss Reptile” in reference to where this creature used to live.

Life reconstruction of Helveticosaurus in watercolors by Christopher DiPiazza.

Helveticosaurus is known from an almost complete articulated skeleton.   Because of this we have know a lot about its anatomy.  However, its combination of features is so unusual that scientists are still unsure as to what Helveticosaurus was, beyond a kind of diapsid reptile.  Diapsids have two openings in their skulls beyond their nostrils and eye sockets.  It's a vast grouping of animals, so it doesn't really narrow down what Helveticosaurus was closest related to.

Helveticosaurus skeleton on display in the Paleontology Museum of Zurich, in Switzerland.

Helveticosaurus had a long tail that was flattened laterally.  This would have been ideal for swimming.   It probably used its tail, powered by large muscles at its base, as its main mode of propulsion in the water.  However, unlike a lot of other marine reptiles, Helveticosaurus also had proportionally long, and very powerful arms.  It may have used these arms, tipped with long fingers which may have been webbed in life, to help steer while swimming.  It has also been suggested that these arms could have been another source of propulsion.

Close up of Helveticosaurus' skull.  It was broken and crushed sometime in the 242 million years since the animal died, but you can clearly make out the extremely long teeth.

The skull of Helveticosaurus is also uniquely short, almost box-shaped and its teeth were long, curved, and pointed.  The longest teeth growing from the front of the snout.  This is an especially odd combination of adaptations since most marine animals with teeth like that possess long snouts to better capture swimming prey.  Most marine animals with short snouts, like Marine Iguanas, have small teeth, that when paired with the blunt snout, are ideal for clipping underwater plants and algae.  It has also been suggested that the short snout, which allows for more concentrated power when biting down, was an adaptation for eating shelled mollusks and crustaceans, like modern walruses do.  However, animals that eat that kind of prey have blunt, wide teeth, for crushing.  Helveticosaurus' long, narrow teeth look like they'd break if they were trying to crush hard shells.  Does this mean Helveticosaurus was an evolutionary failure?  Absolutely not.  It simply means we haven't figured out how it was feeding yet.  Hopefully a new discovery or idea will help us find out in the future!  As of now, most scientists agree that Helveticosaurus was eating meat in some form, based on its teeth.  Exactly which kind and how is still a mystery.

That is all for this week!  What do you think Helveticosaurus was using its odd combination of traits for?  Leave your ideas in the comments below!

Refereces

Bernhard Peyer (1955). "Die Triasfauna der Tessiner Kalkalpen. XVIII. Helveticosaurus zollingeri, n.g. n.sp.". Schweizerische Paläontologische Abhandlungen. 72: 3–50.

Naish, D. (2008). "One of so many bizarre Triassic marine reptiles." Weblog entry. Tetrapod Zoology. 13 September 2008. Accessed 24 July 2009.

Neenan, J. M.; Klein, N.; Scheyer, T. M. (2013). "European origin of placodont marine reptiles and the evolution of crushing dentition in Placodontia". Nature Communications. 4: 1621