Sunday, December 29, 2013

Giraffatitan: Prehistoric Animal of the Week

It's the last Prehistoric Animal of the Week of the year!  Lets go out BIG!  Enter Giraffatitan brancaiGiraffatitan was a sauropod dinosaur that lived in what is now Tanzania, Africa during the late Jurassic about 150 million years ago.  This plant-eater was huge, amongst the largest land animals of all time.  The largest known specimen of Giraffatitan would have been about eighty five feet long!  The name, Giraffatitan, translates to "Giraffe Titan/Giant".  This is in reference to its long neck and front limbs which are similar to those of the comparably puny and unrelated modern giraffe.

Giraffatitan brancai life reconstruction by Christopher DiPiazza.

This dinosaur's long neck and legs would have been used to help it gain access to more vegetation high in the trees, which it would have eaten using its chisel-shaped teeth lining the front of it's mouth.  Since it didn't have any teeth designed for chewing in the back of its mouth, Giraffatitan, like many sauropods, would have swallowed mouth-fulls of foliage whole.  Unlike other kinds of sauropods like Apatosaurus or Barosaurus, Giraffatitan wouldn't have been able to rear up on its hind legs because it's center of gravity was near its chest and shoulders, not its hips.  This anatomical characteristic is common to all members of Giraffatitan's family, called Brachiosauridae.

Giraffatitan skull.  See the nostril holes?

Another interesting characteristic of Giraffatitan's anatomy is it skull, which possesses nostril holes on its forehead that form a crest.  Scientists used to believe that Giraffatitan, along with all other sauropods, lived a semi-aquatic lifestyle and that the nostril placement was for snorkeling.  We now know this is false since the water pressure would likely prevent the dinosaur who's chest was that far beneath the surface from breathing.  Another idea suggested that Giraffatitan would have had a trunk since modern mammals with high nostril placement, such as tapirs and elephants, have trunks.  This hypothesis is likely false as well because a sauropod's teeth were designed for grasping food and some fossilized specimens even show wear from it.  Why would it need a trunk?  Both elephants and tapirs have chewing teeth in the backs of their mouths.  According to the most recent studies, it is most likely that Giraffatitan would have had fleshy nostrils near the tip of its snout when it was alive.

Giraffatitan skeletal mount on display in Germany.

Giraffatitan used to be called Brachiosaurus and was one of two known species within its genus.  In fact, most reconstructions labelled as "Brachiosaurus" are based on Giraffatitan remains.  It was realized that the animal now referred to as Giraffatitan and the other animal that used to share a genus with it, Brachiosaurus altithorax, had enough morphological differences so the genus was split.  Giraffatitan was named and Brachiosaurus is now only a single species. 

That's all for this week!  As always comment below or on our facebook page.  See you inn 2014!

References

Russell, D., Béland, P. and McIntosh, J.S. (1980). "Paleoecology of the dinosaurs of Tendaguru (Tanzania)." Mémoires de la Societé géologique de la France, 59: 169-175.

Taylor, M.P. (2009). "A Re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropod) and its generic separation from Giraffatitan brancai (Janensh 1914)." Journal of Vertebrate Paleontology, 29(3): 787-806.

Witmer, L.M. (2001). "Nostril position in dinosaurs and other vertebrates and its significance for nasal function". Science 293 (5531): 850–853. doi:10.1126/science.1062681. PMID 11486085.

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