As with Tyrannosaurus rex, paleontologists announced their discovery of a new species of enormous carnivorous dinosaur on Thursday. A study released in Current Biology suggests that tiny forelimbs were not an evolutionary fluke, but rather provided survival benefits to ancient predators.
Meraxes, a new, giant predatory dinosaur from Patagonia had short arms like T. rex
Meraxes is the most complete carcharodontosaurid yet from the Southern Hemisphere
It documents peak diversity of carcharodontosaurids just before they went extinc
Meraxes documents convergent evolution of short arms among megapredatory theropods.
One of the most important discoveries of this four-year expedition in northern Patagonia was that a skeleton of Meraxes gigas, which is named after a dragon in Game of Thrones, was unearthed in 2012. Amazingly, the fossils had survived so long. Little over four feet long (127 cm), the skull of the creature that would have been 36 feet long and about 4 tonnes, is all that is left of it.
So long as its arms were two feet long, the animal couldn’t have gotten its mouth to the animal’s head. M. gigas didn’t provide T. rex with its stubby limbs. They were 20 million years away on the evolutionary tree when they died out, with the latter becoming extinct 20 million years earlier.
It’s a different story, though, when it comes to Meraxes’ small arms. The authors feel that the fact that tyrannosaurids, carcharodontosaurids, and abelisaurids all developed short arms indicates to certain advantages.
As their heads became bigger, Makovicky thinks they became the major instrument in their predatory arsenal, taking on the role of forelimbs in lesser species.
Makovicky estimates that Meraxes inhabited the Earth between 90 and 100 million years ago, when the area was wetter, more wooded, and closer to the sea.
An assortment of contemporaneous sauropods would have been prey to them; many were unearthed at the same spot. There were several crests and bumps on the individual’s head, making it a long-lived dinosaur.