Anzu wyliei

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Anzu wyliei

Anzu (an-zoo) is a recently described oviraptorosaurian dinosaur that lived in the latest Cretaceous of what is now North Dakota and South Dakota. Oviraptorosaurs are theropod dinosaurs, but unlike most theropods such as Tyrannosaurus, their teeth have been replaced with a bird-like beak, and although they ran on their hind legs, their front limbs were very large. Many excellently preserved oviraptorosaurs collected in Asia are covered in feathers, and Anzu almost certainly was as well. All this makes them superficially more similar to a large flightless bird (like an ostrich) than a theropod dinosaur, although birds evolved from an entirely different branch of theropod dinosaur. Rather, its bird-like features are classic examples of convergent evolution. Anzu is named for a feathered demon in ancient Mesopotamian mythology.


Genus and Species

Classification: Theropoda, Family Caenagnathidae

Anzu wyliei, only species


Characteristics

Anzu wyliei is a large oviraptorosaur with toothless jaws bearing a bird-like horny beak, and a large, fragile crest on the top of the head. It is bipedal (runs on its hind legs). Both front and hind limbs are long, but slender. The tail is quite short, and its structure indicates that it supported a fan of feathers at its end.


Size

Anzu is the largest known North American oviraptorosaur.

Length: 3-3.5 meters (about 10-11 feet)

Height: 1.5 meters (almost 5 feet) at the hips

Weight: 200-300 kg (440-660 pounds)


Behaviour

It is believed that Anzu was a fast running animal that did not specialize to any particular ecological niche. Its jaw structure indicates that it was capable to eating a wide variety of foods, from vegetation to small animals, and perhaps even eggs. Although Anzu is not related to birds, its bird-like features suggest that it showed many bird-like behaviours. For example, the large crest on its head is made of extremely thin bone, so must have been used only for display, perhaps using it to attract mates, just like the living Australian cassowary does with its crest.


History of Discovery

The first two skeletons of Anzu were discovered in 1998 in South Dakota, and a third specimen was found soon after in North Dakota. Together, about 80 percent of the skeleton is represented. In 2006, Emma Schachner of the University of Utah, Matthew Lamanna of the Carnegie Museum of Natural History and Tyler Lyson of the Smithsonian in Washington realized that each of them was working on partial skeletons of the same species, and decided to work together to reconstruct the skeleton. They were soon joined by Hans-Dieter Sues, an expert in theropod dinosaurs at the National Museum of Natural History of the Smithsonian Institution. The results of their study was published in 2014.


Paleoenvironment

Anzu lived in a well-watered river floodplain, which would have provided a wide variety of food. This is a very different environment than that occupied by Asian oviraptorosaur relatives, which preferred arid to semi-arid conditions.


References

Fawcett, Kirstin, March 19, 2014. Scientists Discover a Large and Feathered Dinosaur that Once Roamed North America. Smithsonianmag.com.
Lamanna, M. C., Sues, H. D., Schachner, E. R.,and  Lyson, T. R. 2014. A new large-bodied oviraptorosaurian theropod dinosaur from the latest Cretaceous of western North America.  PLoS ONE. 9 (3): e92022.doi: 10.1371/journal.pone.0092022