Monday, February 2, 2015

Cryolophosaurus: Prehistoric Animal of the Week

Here in New Jersey we are going through a bitter cold week.  When I walk outside, the air hurts my face.  The air shouldn't be hurting my face.  This week we will be looking at a dinosaur which was discovered in one of the coldest places on earth, enter Cryolophosaurus ellioti.

Cryolophosaurus lived in what is now Antarctica during the early Jurassic Period, between 194 and 188 million years ago.  It measured about twenty one feet long from snout to tail and ate meat.  When alive, Cryolophosaurus was likely the largest predator in its environment.  

Cryolophosaurus ellioti feeding on a young prosauropod, Glacialisaurus.  The bones of Glacialisaurus were found in the same area as those of Cryolophosaurus.  Restoration by Christopher DiPiazza.

One of the things that makes Cryolophosaurus interesting is its unique crest.  Lots of theropods had crests, but almost all of these run parallel to the dinosaur's skull.  Cryolophosaurus was the only known theropod with a crest that runs perpendicular to the rest of the skull, resembling a sort of hairdo.  Lots of people say it looks like it has a pompadour, like women wore in the 18th century.  I think it looks more like Miley Cyrus last year. (You can even hear her pretending to be a Cryolophosaurus in this short video!)  The genus name, Cryolophosaurus, translates to "Ice Crested Lizard-Reptile" in reference to this crest, and to where its bones were discovered...which has lots of ice from what I hear.

Skeletal mount of Cryolophosaurus on display in a Museum in Japan.  Most of the skeleton is based on guesswork, including most of the snout.  This model has a very deep snout, likely inspired by AllosaurusCryolophosaurus may not have looked like that, however.

The biggest misconception about this dinosaur comes from the fact that it was discovered in Antarctica.  Because of this you can find scores of life restorations of it on the internet completely covered in thick feathers to keep warm as it trudges across a wasteland of ice and snow.  The thing that some people forget is that the land mass we now call Antarctica was a lot closer to the equator during the early Jurassic so the environment Cryolophosaurus was living in was significantly warmer than it is today.  In fact, thanks to many plant fossils that were also unearthed from the same rock formations, we know Cryolophosaurus' world was mostly forest and likely was not that cold.  During certain parts of the year it did become chilly, sure, but not nearly as frigid as Antarctica is today.  Also remember that during the early Jurassic, Antarctica was attached to Australia, India, Africa and South America, in a giant supercontinent, called Gondwana.  So even when it did become colder, there was nothing stopping dinosaurs like Cryolophosaurus from migrating north where it was warmer.  There is no evidence suggesting this, but there is a lot we don't know about Cryolophosaurus in general.  We can, however, deduct that it wasn't likely a dinosaur specially adapted for a frigid ice world.

This is a photo of the skull material of Cryolophosaurus that was actually found.  As you can see, most of the snout is missing so the exact shape of this dinosaur's head is a mystery for now.

There is debate as to where exactly Cryolophosaurus lands on the theropod family tree.  At first it was believed to be some sort of early ceratosaur, closely related to Coelophysis and Dilophosaurus.  Ceratosaurs were very successful during the Triassic and Jurassic, and it did sport a crest, like many ceratosaurs did.  Later, upon closer inspections of the few bones paleontologists had to work with, Cryolophosaurus was then thought to be a very early member of the more advanced group of theropods, called tetanurans.  Tetanurans include all theropods beyond the ceratosaurs, basically.  This includes many famous dinosaurs like Megalosaurus, Spinosaurus, Allosaurus, Tyrannosaurus, Velociraptor, Sturthiomimus, Therizinosaurus, all modern birds...and all the dinosaurs in between them.   Cryolophosaurus would have been the earliest known member of this group of dinosaurs.  If more material is discovered and studied, however, views on Cryolophosaurus' identity may change again.

That is all for this week!  As always feel free to comment below or on our facebook page!

References

Chandler, M.A.; Rind, D.; Ruedy, R. (1992). "Pangaean climate during the Early Jurassic: GCM simulations and the sedimentary record of paleoclimate". Geological Society of America Bulletin 104 (5): 543–559. doi:10.1130/0016-7606(1992)104<0543:PCDTEJ>2.3.CO;2.

Hammer, W. R.; Hickerson, W. J. (1994). "A Crested Theropod Dinosaur from Antarctica". Science 264 (5160): 828–830. doi:10.1126/science.264.5160.828. PMID 17794724

Smith, N.D.; Makovicky, P.J.; Hammer, W.R.; Currie, P.J. (2007). "Osteology of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution". Zoological Journal of the Linnean Society 151 (2): 377–421. doi:10.1111/j.1096-3642.2007.00325.x.

 Smith, N. D.; Makovicky, P.J.; Pol, D.; Hammer, W.R.; Currie, P.J. (2007). "The Dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: Phylogenetic Review and Synthesis". US Geological Survey Open-File Report 2007 (1047srp003). doi:10.3133/of2007-1047.srp003.

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