Brachiosaurus were sauropods, the largest and heaviest dinosaurs that ever existed

The remains of thecodontosaurus caducus were discovered in 1952 in a sandstone quarry at Pant-y-ffynnon in Bonvilston in the Vale of Glamorgan.

It is now believed to be the early ancestor of the sauropods - the large four-legged herbivores, like the brontosaurus, with small heads and long necks and tails, and some had body armour.

Originally, the Welsh dinosaur was thought to be a young specimen of another species, but new research by Bristol University has led to it being reclassified.

The dinosaur died in a fall in the south Wales quarry around 210 million years ago.

Tom Sharpe, curator of palaeontology and ancient material at the National Museum of Wales, said a lot of material and bones have been found in the quarries in south Wales

"The deposits in south Wales are well known because at the time south Wales and the Mendips areas were a range of limestones and some of the earlier dinosaur footsteps have been found here," said Mr Sharpe.

"Early dinosaur and mammal bones have also been found in south Wales - because during the late triassic and early jurassic period - both dinosaurs and small shrew like mammals existed here at the same time."

Mr Sharpe is currently working with other groups searching for deposits in quarries in the Vale of Glamorgan.

Having lived during the late triassic and early jurassic period, it's thought the Welsh dinosaur may help to solve the mystery of the origin of the giant sauropods such as brontosaurus, brachiosaurus and diplodocus.

Experts are uncertain how small, fast, two-footed dinosaurs around 230 million years ago evolved into massive 20 tonne creatures millions of years later.