Saturday, 20 September 2014

An Incredible Fossil Of A New Species Of Sauropod

In the late 19th century the frenzy of the Bone Wars, fought between Charles Othniel Marsh and Edward Drinker Cope, uncovered fossils of some of the largest animals to have walked the Earth - Titans which inhabited a lost world now preserved in the rocks of North America. In most cases the fossils were fragmentary, but occasionally they were complete displaying these creatures' full majesty. At least 20 metres in length, if not more in some species, Diplodocus is perhaps the most well known. Yet when palaeontologists conducted digs in South America, from the deserts of Argentina came whispers of dinosaurs which dwarfed their North American cousins.

The larger a creature is, the more likely its remains are scattered after death. Scavengers cause damage to the soft tissue holding the bones together or even remove these altogether. Decay breaks down the skeleton further. The bones become buried and Erosion turns them to dust, whilst simultaneously bringing them to the surface.

As a result, the largest sauropod dinosaurs are known only from fragments. By comparing their bones to those in more complete specimens of smaller species, palaeontologists can extrapolate back to the scale of the original, fragmentary species.

A diagram indicating the bones present in the Dreadnoughtus specimen
Many of the so called largest dinosaurs, such as Futalongkosaurus, have been extrapolated from specimens which are less than 30% complete. Yet now, a new species of giant sauropod has been discovered from a fossil which is an incredible 45% complete, giving us an unprecedented insight into the anatomy of this behemoth.

The 45% skeleton represented 70.5% of the different bone types in sauropod skeletons, but it is the size that is truly astonishing, taking four years to excavate from 2005 to 2009, and a further five years of study. The vertebrae in the neck alone were a metre in diameter, the femurs two metres. Overall the creature was nearly 30 metres in length and weighed in at 65 tonnes; equivalent to a herd of elephants.

Palaeontologists in the field excavating the skeleton of Dreadnoughtus
Yet analysis indicated that it was not fully grown. Exactly how big an adult would be is unknown. Indeed the only reason why it had survived in such good condition is that it was quickly buried by a flash flood before it could be dismembered.

'Every day is about taking in enough calories to nourish this house-sized body. I imagine their day consists largely of standing in one place,' said Dr Kenneth Lacovara from Drexel University. 'You have this 37-foot-long neck balanced by a 30-foot-long tail in the back. Without moving your legs, you have access to a giant feeding envelope of trees and fern leaves. You spend an hour or so clearing out this patch that has thousands of calories in it, and then you take three steps over to the right and spend the next hour clearing out that patch.'

Its size, combined with a weaponised tail, inspired the name of Dreadnoughtus schrani, after the Dreadnought class of battleship; the species name honours the entrepreneur Adam Schran, who helped fund its excavation and study. The actual analysis was done using 3D scans to enable the dinosaur's reconstruction. Digital modelling is the future, especially when dealing with creatures the scale of Dreadnoughtus. It is likely that 3D scans will become increasingly commonplace alongside future research; from lost world to virtual world.