Monday, 24 December 2012

The Smiling Ancestor Of Diplodocus

The classic image of a carnivorous dinosaur is of a creature standing proud on two clawed feet with a long, chunky tail connected to a body supporting two stumpy arms and a powerful, brutish head filled with sharp, serrated teeth. Their herbivorous cousins on the other hand were long and large, with whip-like tails, long necks and tiny heads. While some dinosaurs fit these stereotypes, there were many oddballs which lived alongside them.

The 150 million year old skull of Kaatedocus siberi  from Wyoming, showing its distinctive teeth
Some possessed frills and horns, while others had the ability to fly or at least glide using four feathered wings. Recently, another of these reptilian oddities has been unearthed from 150 million year old rocks in Wyoming. While its smile would not have won it any beauty awards, Kaatedocus siberi, had such large teeth, that its mouth would have been open in a perpetual grin. It was immediately apparent that it was a herbivore.

A reconstruction of its 'smile'
The peg-like nature of the teeth meant that they were too delicate to have torn through flesh and muscle. They were used instead to strip leaves and buds from trees. As to the creature itself, it was classically herbivorous, with a long neck and tail. What is interesting is that its distinctive dentures makes it a likely candidate for the ancestor of the giant Diplodocus.

The Kaatedocus fossils pre-date even the oldest Diplodocus specimens, but strangely they do not display any cranial increases between the two species.

Kaatedocus lived in an environment populated by a number of powerful carnivores. So how did it survive? While it was smaller than its descendants, it still  had a long, powerful tail able to deter potential predators. A recent theory suggests that many of the so called dinosaur species were actually the undeveloped, juvenile forms of adults and that dinosaurs were only a third as diverse as previously thought. These new finds of bizarre dinosaurs show that their family tree is still under-explored. Yet Palaeontologists continue to unearth the remains of new species every year, and as they do, add new branches to the tree of life and their story.