Newly Discovered Giant Predatory Dinosaur Had Tiny Arms, But It's Not Related to T. Rex

The new species of giant dinosaur, called M. gigas, has very short forelimbs, which is similar to the trait of the rex.

T. rex and M. gigas are not the only extinct species on the evolutionary tree.

There are hollow bones and limbs with three main digits in M. gigas. They're some of the biggest predatory animals on the planet.

An artist's impression of Meraxes gigas. (Carlos Papolio)

The arms and legs of the carcharodontosaurid M. gigas were the first parts of the skeleton to be shown to the public.

The dinosaur they found was 45 years old when it died and weighed more than four tons.

What were it used for? The forelimbs had strong muscles, so it's not through a lack of function that the arms shrunk down.

The team behind the study thinks that there must have been some sort of survival advantage, but the large head was most likely the main hunting weapon.

Canale says that the group reached a peak of diversity before they died.

They might have used the arms to support themselves after a break or a fall, or to hold the female during sex.

The excavation site in northern Patagonia, Argentina. (Juan I Canale)

The ornamentations on the skull of M. gigas are thought to have been designed to attract mates.

The team behind the discovery says it's possible that M. gigas will help to answer many more questions about the evolution of dinosaurs.

The fossil is in excellent shape and has a lot of novel information.

The perfect spot was found on the first day of searching. It was one of the most exciting times in my life.

The research has appeared in a journal.