Rare dinosaur tail uncovered (pictures)

In the northern Mexican state of Coahuila, paleontologists have spent the last three weeks brushing away sand and gravel to slowly reveal a 16-foot dinosaur tail with 50 connected vertebrae intact. The tail is thought to have been buried for up to 72 million years.

The dig site is located in the small town of General Cepeda, in the northern Mexican state of Coahuila. Now an arid desert rich with fossils, the area was much closer to the coast during the Cretaceous Period.

The types of vertebrae observed, caudal and sacral, helped scientists to identify the dinosaur as a hadrosaur, or duck-billed dinosaur, though the exact species is still being determined.

The team working to unearth the giant tail comes from Mexico's National Institute for Anthropology and History (INAH) and National Autonomous University of Mexico (UNAM). Here, paleontologist René Hernéndez compares the dinosaur remains to an image of the hadrosaur scapula, called the crested duckbill.

A side view of the tail.

Angel Ramirez Velasco, a member of the team that has been working to unearth the tail, points to the area where the tissue was cartilage between vertebrae.

A closeup look at the nearly complete tail. The remains were reported to the INAH in June 2012, and excavation began earlier this month.