New giant dinosaur predator discovered with tiny arms

WASHINGTON: Paleontologists said on Thursday they had discovered a new giant carnivorous dinosaur species that had a massive head and tiny arms, just like Tyrannosaurus rex.

The researchers’ findings, published in the journal Current Biology, suggest that small forelimbs were no evolutionary accident, but rather gave apex predators of the time certain survival advantages.

Meraxes gigas — named after a fictional dragon in the Game of Thrones book series — was dug up over the course of four years during field expeditions in the northern Patagonia region of Argentina, starting with the skull which was found in 2012.

“We won the lottery and found it literally on the first morning,” senior author Peter Makovicky from the University of Minnesota said. The fossilised remains were remarkably well preserved. The skull is just over four feet long, while the entire animal would have been some 36 feet long, and weighed four metric tons.

Its arms were two feet long, “so it’s literally half the length of the skull and the animal would not have been able to reach its mouth,” said Makovicky.

T. rex didn’t get its tiny arms from M. gigas. The latter went extinct 20 million years before the former arose, and the two species were far apart on the evolutionary tree.

Instead, the authors believe the fact that tyrannosaurids, carcharodontosaurids — the group Meraxes belonged to — and a third giant predator species called abelisaurids all evolved tiny arms points to certain benefits.