Monday, June 9, 2014

Quetzalcoatlus: Prehistoric Animal of the Week

This week's prehistoric animal was requested by our good friend, Joe!  Check out Quetzalcoatlus northropi!  If Tyrannosaurus rex was the king of the dinosaurs, then Quetzalcoatlus was definitely the king of the pterosaurs.  Not only was Quetzalcoatlus likely the largest pterosaur, but it was also likely the largest animal to ever fly!  Its wingspan was up to thirty six feet wide and while standing on the ground it could have stood between fifteen to twenty feet tall! It would have been able to stare a Tyrannosaurus rex in the eye (Right before getting its head chomped off but that's besides the point.)  It lived in what is now Texas, USA, during the late Cretaceous, 68 million years ago.  When alive, it coexisted with many dinosaurs such as Ankylosaurus, Anatotitan(Edmontosaurus), Dracorex, Pachycephalosaurus, Anzu, Troodon, Triceratops...*BREATH*...and Tyrannosaurus during a time within the Cretaceous called the Maastrichtian era.   The genus name, Quetzalcoatlus, is in reference to the ancient Central American god, Quetzalcoatl who took the form of a feathered snake. (strangely not the weirdest mythical creature I have heard of)  Feathered snake...flying snake...flying reptile...pterosaur...sounds good to me!  The species name, norhtropi, is in reference to Jack Northrop, the man who's company made large, tailless air crafts which sort of look like giant pterosaurs.

Quetzalcoatlus northropi by Christopher DiPiazza.

Now here's the thing about Quetzalcoatlus...See, all that stuff up there I just told you?  All the measurements like wingspan and height?  I bet you think we have plenty of fossils to work with from this guy.  How could we not?  It is easily one of the most popular pterosaurs by far.  In actuality the big Quetzalcoatlus northropi is only based on one left wing discovered in the 1970s...that's it.  Everything else we think we know about this animal is based on fossil material that has been gathered over the years from related species.  There is another species of Quetzalcoatlus that was a great deal smaller that has some skull material, and then there is a related animal, called Hatzegoptyeryx, from Europe that scientists believe was very similar to Quetzalcoatlus. (Some believe that the two may even be the same species.) So everything that I am going to tell you in this post is actually educated guesswork based on material from all over the world!  Did that hurt?  I know, I'm sorry.  This is even worse than finding out Santa wasn't real.  If you look at artwork of Quetzalcoatlus starting in the 70s you will see drastic changes in the animal's image as the years go on based on new fossil material that was discovered and applied along the way from related species.

Quetzalcoatlus arm on display at the American Museum of Natural History.

Quetzalcoatlus belonged to a family of pterosaurs called Azhdarchidae.  These were the last and largest pterosaurs to exist before going extinct sixty five million years ago.  They also had some of the oddest proportions of any animal.  The heads possessed large, toothless beaks at the end of long, stiff necks.  Their bodies were proportionally tiny, only about a third the length of their heads!  Their wings were also proportionally shorter when compared to those of some other large pterosaurs (the wing finger was less than half the length of the whole arm), but they were still able to fly quite well.  They also likely had crests on their heads considering that so many other pterosaurs had them, but the exact shape is unknown.  According to what we think we know, Quetzalcoatlus would have been a predator in its environment, hunting small animals like mammals and small dinosaurs.  Despite its ability to fly, it would have also been very comfortable walking on the earth on its four stilt-like limbs.  It may have stalked along the ground, striking any prey with its massive beak much like modern storks, hornbills, and herons do today.  However, the neck of an azhdarchid was not very flexible, and the motion was probably more similar to that of a dipping bird toy...a twenty foot tall dipping bird toy from hell!

Sketch of Quetzalcoatlus walking.

Like I said earlier, Quetzalcoatlus did fly.  You may be wondering how an animal that big was able to ever get off the ground, though.  In fact, only a few years ago there was a proposal by some paleontologists saying Quetzalcoatlus and some of its relatives were actually flightless.  This was later proven to be wrong, however.  See, the arm bones of Quetzalcoatlus were extremely robust and would have anchored HUGE muscles on the chest, back, and bicep areas (experts think about 110 lbs of muscle in these areas to be exact).  We actually see this in a lot of pterosaurs and even modern analogs like bats and birds.  Why would an animal still have all that extra muscle in those places if it wasn't flying?  As it turns out, using the latest technology and fossil information, it was found that Quetzalcoatlus would have actually been a really good flyer, able to stay aloft for several days at thousands of feet above the ground!  The way it would have taken off from the ground also lies in its arms.  Unlike birds, who use their hind legs to launch themselves into the air, pterosaurs had four limbs to do this with, so that's more power right there.  Paleontologists theorize that a taking off Quetzalcoatlus would have looked like someone playing leap frog or pole vaulting.    Check out this video below.  The model isn't Quetzalcoatlus, but it gives the same idea.


That's all for this week!  Hope you enjoyed the largest, yet mysterious, pterosaur!  If you have another request feel free to comment below or on our facebook page!  Also special thanks to Dr. Mark Witton for providing his expert insight on this most grand of pterosaurs!

References

Henderson, D.M. (2010). "Pterosaur body mass estimates from three-dimensional mathematical slicing." Journal of Vertebrate Paleontology, 30(3): 768-785. doi:10.1080/02724631003758334

Kellner, A.W.A., and Langston, W. (1996). "Cranial remains of Quetzalcoatlus (Pterosauria, Azhdarchidae) from Late Cretaceous sediments of Big Bend National Park, Texas." Journal of Vertebrate Paleontology, 16: 222–231.

Witton, Mark P., and Michael B. Habib. "On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness." Ed. Vincent Laudet. PLoS ONE 5.11 (2010): E13982. Web.

Witton, M.P., Martill, D.M. and Loveridge, R.F. (2010). "Clipping the Wings of Giant Pterosaurs: Comments on Wingspan Estimations and Diversity." Acta Geoscientica Sinica, 31 Supp.1: 79-81

Witton, M.P., and Naish, D. (2008). "A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology." PLoS ONE, 3(5): e2271. doi:10.1371/journal.pone.0002271

Witton, Mark P. Pterosaurs: Natural History, Evolution, Anatomy. N.p.: n.p., n.d. Print.

2 comments:

  1. "In fact, only a few years ago there was a proposal by some paleontologists saying Quetzalcoatlus and some of its relatives were actually flightless. This was later proven to be wrong, however."

    Which papers are those (in reference to both the proposal & the proof showing otherwise)? Many thanks in advance.

    -Hadiaz

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    Replies
    1. Sure thing. The proposal that large azdarchids were flightless was by Donald Hendersen from 2010. "Pterosaur body mass estimates from three-dimensional mathematical slicing." It was in the Journal of Vertebrate Paleontology. The response proving that they probably could fly after all was in the same year by Marc Witton and Michael Habib. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013982

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