New species of small-armed dinosaurs such as T. rex . have been discovered

That changed with the discovery of M. gigas, thanks to the remarkably complete fossil.

“For the first time we know, in such detail, certain parts of the anatomy of these giant carnivorous dinosaurs,” Kanal said.

The researchers found a nearly complete forelimb, allowing them to conclude that M. gigas had arms as small as this large dinosaur, a physical feature shared with T. rex that has long puzzled paleontologists.

They also found an almost complete skull and foot, Canal said, shedding light on how this group of dinosaurs evolved, explaining that there was a trend towards larger body sizes, larger skulls and smaller arms in proportion to the body.

‘There was some kind of arms race’

The fossil was found in the Huincul Formation, where the study said the remains of one of the largest known land animals of all time, Argentinosaurus huinculensis, were found in the same period as the fossil of M. gigas.

The area is also known to have been home to other carnivores, albeit smaller than the M. gigas dinosaurs, as well as other types of long-necked herbivores.

It’s often very difficult to determine what dinosaurs ate, Kanal said, but loose teeth have been found at excavation sites where fossils of herbivorous dinosaurs were discovered alongside carnivorous dinosaurs.

He added that this means that we can say that M. gigas was preying, at least in part, on these long-necked herbivores such as Argentinosaurus huinculensis.

“It is no coincidence that giant herbivorous dinosaurs and giant carnivorous dinosaurs lived in the same environments,” Kanal said, who explained that as herbivores evolved larger bodies as a form of defense, the carnivores did so in order to prey on them.

“There was some kind of arms race,” he said.

“No direct relationship” with T. rex

But the team says that M. gigas evolved separately from T. rex and became extinct about 20 million years before T. rex walked on Earth.

Kanal said that while both dinosaurs had large heads and small arms, their skeletons were very different.

“There is no direct relationship,” Kanal said.

Kanal said that the ancestors of M. gigas had longer arms, smaller heads, and arms that were important in hunting, but that has changed over time.

Previous research found that dinosaur species such as M. gigas and T. rex developed smaller arms the larger their heads.

The channel said that this indicates that the weapons were not used for hunting and instead used their heads to kill their prey.

“What I believe is that in more advanced forms… activities related to predation, such as capturing or carrying prey, could have been done immediately with the head,” he said.

However, the fossil shows that while the arms were short, they were muscular and the chest muscles were well developed, Kanall said.

“This does not correspond to a limb that has no function,” he said, adding that it could be used to help raise the ground or support the female in mating. Researchers do not know whether this fossil belonged to a male or a female dinosaur.

The team also found that M. gigas had decorations such as bumps, grooves, protrusions and tiny spikes on its skull, which were likely used to attract potential mates.

Canal said there is still more work to be done on M. gigas, and a colleague at the museum is writing a letter on his feet and arms.

In addition, there are many fossils that have not yet been excavated in the area, as well as dinosaur footprints for analysis, he said.

“We have a lot of work to do,” Kanal added.