Sunday, May 18, 2014

Dakosaurus: Prehistoric Animal of the Week

Before we get into this week's creature, let me just remind everyone that the newest installment to the Godzilla franchise came out this past weekend.  I saw the movie in IMAX 3D last night and it was awesome.  It's really cool to see the most famous movie dinosaur of all time on the big screen again.


You may know that we have reviewed a Godzilla dinosaur on here before.  This week we will be looking at yet another prehistoric beast with connections to the "King of the Monsters."  Check out Dakosaurus andiniensis!

Dakosaurus andiniensis by Christopher DiPiazza.

Dakosaurus was an extinct genus of crocodile that belonged to the family called Metriorhynchidae.  Metriorhynchids were prehistoric crocodiles that were specially adapted to living in the ocean.  Their limbs were like flippers and their flattened tails even had flukes on them like sharks, dolphins, and their fellow reptiles, the ichthyosaurs and mosasaursDakosaurus andiniensis lived in the oceans that once covered what is now Argentina during the Late Jurassic to the Early Cretaceous, about 145 to 140 million years ago.  The genus name, Dakosaurus, translates to "biter lizard" in reference to the creature's formidable teeth.  There are actually a few species within the Dakosaurus genus, but I want to focus specifically on the species, Dakosaurus andiniensis, because of its nickname, "Godzilla", given to it by the scientists who discovered its skull.  It earned this name because of its unusual snout, which was short and deep, and extremely long, serrated teeth.  It measured about thirteen feet long from snout to tail and would have been a meat-eater.

Fossilized skull of Dakosaurus andiniensis.  It looks mean!

Dakosaurus' teeth were unique in that they were both laterally compressed and serrated.  This is a feature more commonly seen in certain kinds of meat-eating dinosaurs.  In fact, when the isolated teeth of Dakosaurus were first discovered, they were initially believed to have been from a Megalosaurus, not a crocodile.  The skull of Dakosaurus had openings towards the back, called fenestrae, that would have anchored powerful jaw muscles in life.  This, combined with the fact that its teeth were deeply rooted within the jaws, means that Dakosaurus would have been able to bite down with extreme force.  It is likely that Dakosaurus was a top predator and was able to hunt most other animals it shared its habitat with, including other marine reptiles. 

Nobody is exactly sure how Dakosaurus would have reproduced.  There is evidence that other prehistoric marine reptiles, like mosasaurs and ichthyosaurs, gave birth to live young in the water, much like modern whales.   Dakosaurus' closest relatives, the crocodilians, we know lay eggs in nests, however.  It is possible Dakosaurus could have hauled out onto beaches to lay eggs like modern sea turtles do if it was like the rest of its family.

That is all for this week!  Next week I shall be in London visiting friends.  Tune in for a special English dinosaur of the week!  As always comment below or on our facebook page.

References

Gasparini Z, Pol D, Spalletti LA. 2006. An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia. Science 311: 70-73.

Vignaud P, Gasparini ZB. 1996. New Dakosaurus (Crocodylomorpha, Thalattosuchia) from the Upper Jurassic of Argentina. Comptes Rendus de l'Académie des Sciences, Paris, 2 322: 245-250.

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