T-rex ancestor found in China

 

The earliest known forerunner of the Tyrannosaurus rex, Guanlong wucaii, has been found in China.

AFP/Zhongda Zhang-IVPP

Fossil hunters in China say they have found the earliest known forerunner of the Tyrannosaurus rex, the mighty flesh-ripping dinosaur beloved of children and Hollywood.

Uncovered in Wucaiwan in the western province of Xinjiang, the species has been dubbed Guanlong wucaii, "crowned dragon of the five-coloured rocks", a reference to the tint of the earth in which it was found.

It hails from the Late Jurassic Period, around 161 million to 156 million years ago, according to the discoverers, led by Xu Xing of the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing.

By comparison, the T-rex lived much later, in the Late Cretaceous era, enjoying a 20-million-year reign of terror that ended with the extinction of the dinosaurs some 65 million years ago.

Nose to tail, T-rex measured up to 13 metres in length, whereas the best preserved of the two fossils unearthed in Wucaiwan suggest a creature that was about three metres long.

Despite these differences, the "crowned dragon" shows all the key ancestral hallmarks of the tyrannosaurids.

It shares their enlarged skull, two powerful rear feet, stubby forelimbs that end in a powerful three-fingered hand and long, blade-like teeth that suggests it too was a predator to be reckoned with.

But palaeontologist believe the "primitive" look of the pelvis also suggests something else.

It supports a theory first put forward in the 1990s that the tyrannosaurids, despite their great size, evolved from a species of swift, small-bodied dinosaurs called coelurosaurs.

Guanlong also had a highly elaborate, fragile crest, a "crown" that ran almost the entirely length of its long upper jaw.

This crest is "surprising," given that it would have surely hampered the beast in its hunt for food, the palaeontologists say.

They speculate that it was an ornament that may have been used to lure a mate or show off status. Many vertebrate species today use these tools, such as peacocks with their tails and elks with their antlers, even if the device carries a cost in movement.

Xu has earned a reputation for being the world's most successful fossil finder, unearthing extraordinary specimens that have shed light in particular on birds, spurring the theory that modern birds are the descendants of dinosaurs.

Most of his big finds have come from lake deposits in Liaoning province, in the north east of China, that are between 128 and 110 million years old.

Their study is published in Nature, the British weekly science journal.

 

Carnivorous baby dinosaurs were born with teeth and 'ready to hunt', scientists find

 

A baby tyrannosaur from the Cretaceous Period of North America, based on partial fossils unearthed in the US. (Reuters: Julius Csotonyi)

Silhouettes of two baby tyrannosaurs based on partial fossils unearthed in the US state of Montana and in the Canadian province of Alberta.(Reuters: Greg Funston/University of Edinburgh)

Scientists for the first time have found embryonic remains from a group of ferocious meat-eating dinosaurs that includes the Tyrannosaurus rex.

They found fossilised jaw and claw bones that show these record-size babies looked a lot like adults and were "born ready" to hunt.

The fossils, the researchers said, represented two species from the tyrannosaurs group, the apex predators in Asia and North America during the Cretaceous Period toward the end of the dinosaur age.

The bones indicated these were bigger than any other known dinosaur babies — 1 metre long, or the size of a medium dog — and hatched from what must have been enormous eggs, perhaps exceeding the 43-centimetres in length of the largest dinosaur eggs currently known.

University of Edinburgh palaeontologist Greg Funston, lead author of the research published in the Canadian Journal of Earth Sciences, said the scientists were amazed at how similar the embryonic bones were to older juvenile and adult tyrannosaurs.

He also noted that the jaws boasted functional teeth.

"So although we can't get a complete picture, what we can see looks very similar to the adults," Mr Funston said.

He added it appears that tyrannosaurs were "already possessing some of the key adaptations that gave tyrannosaurs their powerful bites".

"So it's likely that they were capable of hunting fairly quickly after birth, but we need more fossils to tell exactly how fast that was," he said.

The roughly 77 million-year-old jawbone, about 3 centimetres in length, was unearthed in the US state of Montana, and may belong to a species called Daspletosaurus.

The roughly 72 million-year-old wedge-shaped claw came from Canada's Alberta province and may belong to a species called Albertosaurus.

Both are slightly smaller cousins of Tyrannosaurus rex. The largest-known tyrannosaurs topped 12 meters-long and 8 tonnes in weight.

However, the jaw possesses distinctive tyrannosaur traits, including a deep groove inside and a prominent chin.

Reuters