Dinosaur discovery hints at why T-rex had small arms

A team of scientists in Argentina says they have discovered a new giant predatory dinosaur with a huge head – but arms small for its size.

Writing in the journal Current Biology, Scientists say large skeletal remains of a previously unknown species were excavated in northern Patagonia.

Meraxes gigas was about 36 feet (11 m) long, with a 4-foot skull—but its arms were only 2 feet long.

Scientists believe that the small limbs gave the carnivores a survival advantage.

“I am convinced that those relatively small arms have some sort of function. The skeleton shows large muscles and fully developed pectorals, so the arm had strong muscles,” said Juan Canal, lead author of the study.

“They may have used the arms for reproductive behavior such as holding the female during mating or supporting themselves to stand back after a break or a fall,” he added.

Co-author Peter Makovsky said the dinosaur’s arms were “literally half the length of the skull and the animal wouldn’t be able to get into its mouth.”

Makovicki said he believed the species’ large heads were the main predatory tool, performing functions that weapons would have performed in smaller species.

Meraxes gigas — named after a fictional dragon from the Game of Thrones book series — belong to the carcharodontosaurids, or shark-toothed lizards.

The four-ton reptile is believed to have roamed the Earth about 90-100 million years ago.

Scientists say two other species — tyrannosaurs and abelisaurides — also developed small arms for similar reasons.