'Chicken from Hell' skeleton sheds light on 250kg feathered dinosaur Anzu wyliei

Saturday, May 23, 2015

A 250-kilogram 'chicken from hell' with features similar to the cassowary is the latest dinosaur discovery by US scientists, who have named the "scary and absurd" creature after a mythical bird-like demon.

Almost a full skeleton of the sharp-clawed, crested raptor that roamed the Hell Creek rock formation in North and South Dakota 66 million years ago was pieced together from three different specimens.
They have named it Anzu wyliei: "anzu" after a bird-like demon in Mesopotamian mythology, and "wyliei" after Wylie J Tuttle, the dinosaur-loving grandson of a Carnegie Museums of Pittsburgh trustee.

"It was a giant raptor, but with a chicken-like head and presumably feathers. The animal stood about 10 feet tall, so it would be scary as well as absurd to encounter," says University of Utah biology postdoctoral fellow Emma Schachner, a co-author of a new study of the dinosaur.

Pieces of a strange-looking puzzle
Three partial skeletons of the dinosaur – almost making up a full skeleton – were excavated from the uppermost level of the Hell Creek rock formation in North and South Dakota, a formation known for abundant fossils of Tyrannosaurus rex and Triceratops.

At a scientific meeting in 2005, Matthew Lamanna of the Carnegie Museum of Natural History in Pittsburgh, Tyler Lyson of the Smithsonian in Washington and Dr Schachner realised they had fossils of the same new species of dinosaur.

They soon began collaborating on the new study and asked Hans-Dieter Sues to join them because he was an expert on this type of dinosaur.

"It took years since all of us had busy schedules, and I moved to Utah in 2010 to work on reptile respiratory evolution," says Dr Schachner.

Having a nearly complete skeleton of Anzu wyliei sheds light on a category of oviraptorosaur theropod dinosaurs named caenagnathids, which have been known for a century, but only from limited fossil evidence.

"I am really excited about this discovery because Anzu is the largest oviraptorosaur found in North America," she said.

"Oviraptorosaurs are a group of dinosaurs that are closely related to birds and often have strange, cassowary-like crests on their heads."

A dangerous life
Lead researcher Dr Lamanna says they call the creature the "chicken from hell".

And while it might look rather strange, the bones collected show that Anzu needed to be tough to survive.

Not only did it share the Hell Creek formation with the most notorious carnivore of all time, the T-rex, but Anzu seems to have been in some scrapes.

Two of the three specimens show clear evidence of injuries: one has a broken and healed rib, while the other has an arthritic toe bone that may have been caused by an avulsion fracture (where a tendon ripped a piece off the bone to which it was attached).

"These animals were clearly able to survive quite a bit of trauma, as two of the specimens show signs of semi-healed damage," says Dr Schachner.

"Whether these injuries were the result of combat between two individuals or an attack by a larger predator remains a mystery."

Much to learn
As much insight as the Anzu skeletons provide, paleontologists still have much to learn about North American oviraptorosaurs.

"We're finding that caenagnathids were an amazingly diverse bunch of dinosaurs," says Dr Lamanna.
"Whereas some were turkey-sized, others - like Anzu and Gigantoraptor - were the kind of thing you definitely wouldn't want to meet in a dark alley. Apparently these oviraptorosaurs occupied a much wider range of body sizes and ecologies than we previously thought.

"After nearly a century of searching, we palaeontologists finally have the fossils to show what these creatures looked like from virtually head to toe. And in almost every way, they're even weirder than we imagined."

By Cristen Tilley


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