A Completely New Group Of Reptiles

A reconstruction of Reveueltosaurus callendari

An ongoing argument in biology is the number of species which live on the planet. The estimates range from 2 million to an astounding 100 million plus. Yet these figures pale in comparison to those often quoted for the number throughout the entire history of the Earth. Some say that the species alive today represent just 1% of the total which have ever lived.

Everywhere from the deep jungles of Borneo to ancient rocks in China, unknown organisms are discovered. Such finds represent new species or genera. It is a rare occurrence to be able to name a completely new family. While this does happen occasionally within the world of invertebrates, on account of their long and rich evolutionary history, it is an incredibly unusual for a whole new family of vertebrates to be recognised.

In 2004, no less than eight three foot long specimens from a crocodile-like creature were recovered from the 213 million year old Petrified Forest National Park in Arizona. They were given the name of Reveueltosaurus callendari. 

Excavations were resumed early this year, resulting in 3 more skeletons. A complete study of the remains showed that, rather than being a species of an early plant eating dinosaur, they represented a completely unknown family of ancient reptiles. 'We realized that it wasn't a dinosaur. It was a whole new family of reptile that no one had ever seen before,' said Bill Parker, park palaeontologist. What made the specimens interesting is that they were found very close together in the same geological horizon.

This suggests that the creatures died and were buried at the same time. The entire park 213 million years ago was a semi-desert scarred by streams and rivers. It is possible that a flash flood killed and buried the reptiles, preserving their bones for eternity. A team from Yale have already returned to the formation to extract more fossils from the ancient floodplain. The Triassic was a time of great transition. Who knows that wonders may be recovered from the tombs of red rock?