April 13, 2011

New Toothsome Fossil Fills Evolutionary Gap

The discovery of a 200-million year old fossil of a reptile with extremely pointed teeth, from an area now known New Mexico, is filling a gap in previously known dinosaur evolution, the Associated Press reports.

Named Daemonosaurus chauliodus, from the Greek words "daimon" meaning evil spirit and "sauros" meaning lizard or reptile. Chauliodus is derived from the Greek word for "buck-toothed" and refers to the species' big slanted front teeth.

This species featured a short snout and angled front teeth, features never before been seen in a Triassic era dinosaur, explains Hans-Dieter Sues of the Smithsonian's National Museum of Natural History. The discovery is reported in the current edition of the British journal Proceedings of the Royal Society B.

Sues explains how the discovery adds details into the evolutionary story between the dinosaurs that lived in what is now the Amazon river basin about 230 million years ago and later theropods such as Tyrannosaurus rex.

"Features of the skull and neck of Daemonosaurus indicate it was intermediate between the earliest known predatory dinosaurs from South America and more advanced theropods. One such feature is the presence of cavities on some of the neck vertebrae related to the structure of the respiratory system," said Sues.

The fossil was discovered near Ghost Ranch, N.M., well known for the thousands of fossilized skeletons found there, notably the small dinosaur Coelophysis. Only the head and neck of Daemonosaurus were unearthed so researchers cannot be certain of its final size but estimate it to be about that of a large dog.

Paleontologist Paul Sereno of the University of Chicago, who was not part of the research team, offered his opinion on the findings so far, "It looks to be a mean character. I can't wait to see if they get any more of the skeleton," Sereno told the Associated Press.

"This fits in quite nicely between the dinosaur groups," Sereno continued, "even though its face is unlike anything that would have been expected in these early dinosaurs, which tended to have more elongated snouts."

This find shows there is still much to be learned about the early evolution of dinosaurs. "The continued exploration of even well-studied regions like the American Southwest will still yield remarkable new fossil finds," Sues concluded.


Image 1: This rendering of Daemonosaurus chauliodus shows its size relative to an American quarter. The species name chauliodus is derived from the Greek word for "buck-toothed" and refers to the species' big slanted front teeth. Credit: Jeffrey Martz

Image 2: The skull of Daemonosaurus chauliodus is narrow and relatively deep, measuring 5.5 inches long from the tip of its snout to the back of the skull and has proportionately large eye sockets. The upper jaw has large, forward-slanted front teeth. Credit: Carnegie Museum of Natural History


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