On the 5th December scientists reported in the journal Biology letters that fossils of an arm bone and pieces of bone from the back and hips, unpacked from the drawers of London's Natural History Museum, could belong to the earliest dinosaur ever found.
Named Nyasasaurus parringtoni, the ancient animal was the size of a Labrador dog with a tail more than a metre long. It lived about 245 million years ago, which is 10 to 15 million years before any previously known dinosaur or dinosaur-like creature. This means that dinosaurs evolved much earlier than previously thought, in the Middle rather than Late Triassic.
The fossils were unearthed in the 1930s by Cambridge University’s Rex Parrington, from the Manda Beds near Lake Nyasa (now Lake Malawi), Tanzania, hence the species name. They were studied by former curator Alan Charig in the 1950s during his PhD, and then donated to the Museum. Although he intended to publish this work, he passed away before finishing it.
Dinosaur features
An international team, including Museum dinosaur expert Dr Paul Barrett, decided to take another look at the fossils. They found dinosaur features in the bones, as Barrett explains. 'Although the material is limited, it is very distinctive and completely unlike that of other contemporary reptiles.'
'In particular, a prominent crest, found on the upper arm bone, is a feature found only in Nyasasaurus and other dinosaurs. This crest would have supported large muscles, associated with strong grasping forelimbs.'
The microscopic structure of the bone tissue also shows a woven texture and large spaces for blood vessels, which indicates that the animal grew quickly, typical of dinosaurs.
The team also studied a second fossil from Iziko South African Museum, Cape Town, South Africa. It contained several bones from the neck of another Nyasasaurus individual that also shows many dinosaur-like features. It was originally described by South African palaeontologist Sidney Haughton in the 1930s, but had been largely overlooked until now.
Dinosaur or closest relative?
Because the remains of Nyasasaurus are incomplete, there is still room for debate over its exact relationship with other Triassic reptiles.
The team's analysis suggests that is it is most likely a very early dinosaur, as it shares most features with this group. Barrett adds, 'It is not clear if it belongs to any particular dinosaur subgroup such as the meat-eating theropods or plant-eating sauropodomorphs.'
It is possible that instead of being a true dinosaur, Nyasasaurus might have been a very close relative, lying just outside the dinosaur group. ‘If the newly named Nyasasaurus parringtoni is not the earliest dinosaur, then it is the closest relative found so far,' says Lead author Dr Sterling Nesbitt from the University of Washington.
For more information visit:
http://www.nhm.ac.uk/about-us/news/
No comments:
Post a Comment