Intact Hadrosaur Tail Found
July 23, 2013

First Intact Hadrosaur Tail Discovered In Mexican Desert

Lee Rannals for - Your Universe Online

Paleontologists have uncovered 50 vertebrae of the only complete, articulated hadrosaur tail to be found in the desert of Coahuila in Mexico.

The scientists carefully removed sedimentary rock that covered the vertebrae to discover the skeleton of a 72 million-year-old hadrosaur tail that reaches nearly 16-feet in length. The 50 vertebrae excavated remain bound together the same way as when the dinosaur inhabited the planet.

Felisa Aguilar, a paleontologist from INAH-Coahuila Center who directed the excavation, said the tail is less than half the skeleton, which means the hardosaur could have reached a total body length of 40-feet. Aguilar added that the recovery of this skeleton is of great importance because it is rare for paleontologists to find this type of specimen with most of its bones still intact.

"For the biological study of dinosaurs this finding is important because we will have a sequence that will reveal the characteristics of the vertebrae. How they will be seen differentiating in size depends on their position in the spine," said science teacher Angel Ramirez Velasco, paleontologist and team member of this project.

Velasco said that the space where the cartilage was, between vertebrae, would help them to study the biomechanics of the massive dinosaur's tail.

In order to preserve the tail, paleontologists had to remove the sedimentary rock fossils along a horizontal plane of layers. Aguilar said the rescue started by cleaning the surface and setting the excavation grid.

They originally thought their work area would be 3 by 6 meters (10 by 20 feet), but as the skeleton emerged, they realized that they  needed to extend the area to 4 by 8 feet, in order to unearth the complete tail.

He said they took photographic records, drawings and video of the whole process to preserve all details of the project. According to Aguilar, it is necessary to analyze the type of environment in which they found the hadrosaur in order to help scientists determine the cause of his death. So far, Aguilar and his team believe the hadrosaur died of natural causes.

In previous studies, scientists found that the hadrosaur had an unusual jaw in that it wasn't hinged in the same way as modern animals, allowing for simple up and down movements. Instead, they had a hinge between the upper jaws and the rest of the skull so that when they bit down on their food the upper jaws were forced outward, flexing along this hinge so that the tooth surfaces slid sideways across each other to grind the food. They were able to chew up and down, sideways and front to back, allowing the animal to be a dominant herbivore.