Saturday, 8 October 2011

A New Hoard Of Dinosaur Tracks

One of the tracks and a plaster cast of Acrocanthosaurus atokensis
Large fossilised bones and shells are all very well, but trace fossils are just as interesting. They give us the key to unlock how creatures lived, fed and reproduced. Perhaps the most famous trace fossils are tracks. They can yield a surprising amount of information. A recent discovery of a collection of Australian polar dinosaur tracks gave palaeontologists an insight into the migration patterns of polar dinosaurs. A second series of tracks from a large predatory dinosaur have been discovered in south west Arkansas, USA.

Researchers from the University of Arkansas, Fayetteville, found the tracks on private land that covered an area equivalent to 2 football fields. The fossils were made primarily by Acrocanthosaurus atokensis while a small portion were made by giant, plant-eating sauropods, possibly Pleurocoelus or  Paluxysaurus. The predator's footprint was 60 centimetres long by 30 centimetres wide, showing that it was made by a large member of the species, which itself was one of the largest predatory dinosaurs to have ever lived.

Interestingly, the tracks date to between 115 and 120 million years old. At this point in the Cretaceous, giant sauropods were in decline due to rising sea levels and would only make a return, albeit for the last time, with the giant Titanosaurs. The tracks of a large predators and plant-eating giants in the same place show that there was still a strong predator/prey relationship between these two dinosaur groups. 'Through tracks, we can learn all sorts of things about dinosaur biomechanics and behavior,' said Brian Platt of the University of Kansas. 'Dinosaur bones can be dragged away by animals or swept out to sea. But we know that about 120 million years ago, dinosaurs walked right through here.'