New species of predatory dinosaur found

While it may have had a ferocious set of teeth and a terrifying turn of speed, Tyrannosaurus rex is also famed for its absurdly weedy ‘arms’.

Now experts have found the dinosaur’s small forelimbs are perhaps not as unique as first thought according to Daily mail.

Palaeontologists have discovered a new species of dinosaur in northern Patagonia that has similar short arms with two-fingered claws that look similar to those of the famous predator.

However, the newly discovered carnivorous dinosaur is not thought to be closely related to the T. rex, suggesting its stumpy forelimbs may have evolved independently.

It suggests such tiny arms may have evolved several times in dinosaurs and so could have served a useful purpose rather than being vestigual limbs.

Some palaeontologists, for example, have suggested that T. rex used its forelimbs to hold down its food as it tore chunks from it.

The new dinosaur, which like T. rex is a theropod, has been named Gualicho shinyae.

It lived in the Late Cretaceous period, between 100.5 million and 66 million years ago when giants such as Argentinosaurus, measuring more than 130 feet (40 metres) long, roamed the region.

However, Gualicho shinyae belongs to a different branch of the family tree to T. rex, meaning its unusual arms must have evolved independently rather than from a common short-armed ancestor.

‘Gualicho is kind of a mosaic dinosaur, it has features that you normally see in different kinds of theropods,’ said Peter Makovicky, The Field Museum’s Curator of Dinosaurs.

‘It’s really unusual – it’s different from the other carnivorous dinosaurs found in the same rock formation, and it doesn’t fit neatly into any category.’

Gualicho is an allosaurid – a branch of medium-to-large carnivorous theropod dinosaurs.

It would have stood around six feet tall and was 25-30 feet long, weighing around 1,000lbs, about the same as a polar bear.

However, its tiny forelimb arms would have been just two feet long.

While the skeleton discovered is incomplete, palaeontologists estimate it was a medium-sized predator weighing around a thousand pounds, which is about the same weight as a powerful polar bear.

It looked very different from the other dinosaurs that lived near it, most closely resembling Deltadromeus – a leggy, carnivorous dinosaur with slender arms found in Africa, which it appears to be closely related to.

Despite its large size, Gualicho’s forelimbs were the size of a human child’s, and like T. rex, it had just two digits – a thumb and forefinger

While Gualicho does not explain why so many theropods had pint-sized forelimbs, it adds to growing evidence that the trait evolved independently numerous times.

‘By learning more about how reduced forelimbs evolved, we may be able to figure out why they evolved,’ Dr Makovicky explained.

The dinosaur’s name hints at the story of its discovery in 2007, during an expedition to the fossil-rich Huincul Formation of northern Patagonia.

N.H.Kh