September 9, 2010

Hump-backed Dinosaur May Confirm Link To Birds

Paleontologists in Spain have discovered a near-complete fossil of a bizarre new hump-backed dinosaur they believe predates the well-known dinosaurs that once ruled the Earth.

Francisco Ortega of Spain discovered the fossil, and named it Concavenator corcovatus, meaning "the hunchback hunter from Cuenca."

The remains were uncovered in the Las Hoyas formation in Spain's Cuenca province. The area has produced a treasure trove of finds dating back 120 to 150 million years ago during the Lower Cretaceous period.

Ortega said the hump might have been used to store fat, or to regulate body temperature.  However, it might have been used as a way for the dinosaurs to differentiate themselves or communicate with each other, he added.

The fossil is as pristine as the dinosaur is "bizarre," said Fernando Escaso of the Autonomous University of Madrid.

"This dinosaur is very remarkable," he said during an interview with the AFP news agency.

"It is a unique specimen. It is the most complete dinosaur ever found in the Iberian Peninsula and is a new species of theropod," he said.

A theropod is a carnivore that moves on two rear limbs.

At nearly 20 feet long from snout to tailtip, the new dinosaur is the oldest-discovered member of a branch of Carcharodontosauria, the largest predatory dinosaurs that ever lived.  Scientists had long believed these massive dinosaurs were confined to southern continents, until now.

The lineage expanded dramatically over the eons in both size and number of species, and includes the 47 ft. long Giganotosaurus and the 44 ft. long Carcharodontosaurus, each of which weigh up to eight tons.

The new fossil has jaws and small, clawed forelimbs resembling those of the Tyrannosaurus rex, which is part of different dinosaur family.

However, the similarities end with the spine, which is shockingly curved and includes a small hump, Ecaso said.

"It is the first time we have ever seen a structure like this on the spine of a dinosaur, although it is common on some animals today, such as cows."

"At the moment, the function of this structure is unclear. We believe that the animal was not diseased because the spine shows no sign of being cracked or broken, we think it is a feature of this species. One hypothesis is that it was a reservoir of fat."

The hump is not the only bizarre feature of the Concavenator.  Its limbs have knobs resembling proto-feathers -- further evidence of the connection between early theropods and birds, Ortega said.

The study is published Thursday in the journal Nature, and can be viewed at http://www.nature.com/news/2010/100908/full/news.2010.455.html.


Image Caption: Concavenator corcovatus may have had quills and a mysterious hump. Credit: Raúl Martín/Nature