Thursday, 20 October 2011

A New Tyrannosaurid Fossil Is the Best Preserved On Earth

The Tyrannosaurids are the most famous group of dinosaurs on Earth. While they are not the most diverse group on Earth with around 20 different species spread out over 5 groups, they are one of the most incredible, containing a vast array of shapes and sizes from the chicken sized Nanotyrannus lancesis to one of the most famous of dinosaurs Spinosaurus aegyptiacus. The best preserved fossil tyrannosaur is the 85% fossil of Tyrannosaurus rex better known as 'Sue.'

The beautiful fossil of Sciurumimus albersdoerferi from Bavaria
Sue was a truly incredible find. Tyrannosaurid fossils are very rare and the very complete nature of the find made it an instant palaeontological celebrity. However a team of German palaeontologists have discovered a fossil which is even more complete than Sue. It was excavated from a fossil locality near the town of Kelheim in Bavaria about a year ago and unveiled on Wednesday 20th October  by scientists from the Bavarian Palaeontological and Geological Collections (BSPG).

BSPG conservator Oliver Rauhut described it as 'the best preserved dinosaur skeleton to ever be found in Europe.' The fossil was preserved in 135 million year old limestone. This was very fortunate as Bavarian limestone is very fine grained and produces very well preserved specimens. Fossils from the area are some of the most desirable due to their high quality and the creamy, attractive limestone on which they are preserved. The most well known locality is the Solnhofen Plattenkalk where the first Archaeopteryx fossil was discovered.

What makes this fossil special is that, apart from being a completely new species now named Sciurumimus albersdoerferi, it was 98% complete. The best preserved Tyrannosaurid fossils until now were 80 to 85% complete skeletons. This fossil is just 72 centimetres long, but all the bones are present and there are traces of the skin and hair-like structures which may have been proto-feathers. While the species might just be a juvenile member of a known species rather than an unknown one, its complete nature means that this question can be quickly solved.

By studying the bone sizes and development, palaeontologists were able to establish that the dinosaur was young when it died. The fossil was quickly marked as a German cultural asset which ensures it will remain in Germany. It currently resides in the hands of a private collector whose name has not been disclosed. Yet Dan Ravasz, a spokesperson for the Munich Rock, Gem and Mineral Fair, said that it will eventually be loaned to a museum.