At the time, the area would have been hot and humid with lots of waterways and vegetation, including tall trees, Juan Canale, project manager at the Ernesto Bachmann Paleontological Museum in Neuquén, Argentina, told CNN.
The carnivore belongs to the Carcharodontosauridae group of dinosaurs, which lived in the Cretaceous, 145 to 66 million years ago, according to the study.
A raft of Carcharodontosauridae fossils have been found over the past 30 years, but little was known about their skulls, forearms, or feet.
That changed with the discovery of M. gigas, thanks to the remarkably complete fossil.
“For the first time, we know, in great detail, parts of the anatomy of these giant carnivorous dinosaurs,” Canale said.
The researchers found an almost complete forelimb, which led them to conclude that M. gigas had tiny arms for such a large dinosaur, a physical feature shared with T. rex that has long puzzled paleontologists.
They also found an almost complete skull and foot, which allowed them to shed light on the evolution of this group of dinosaurs, Canale said, explaining that there was a trend toward larger body sizes, larger skulls and smaller arms in proportion to the body.
“There was a kind of arms race”
The fossil was found in the Huincul Formation, where the study indicates that remains of one of the largest known land animals of all time, Argentinosaurus huinculensis, have been discovered and date to the same time period as the fossil. Mr gigas.
The area is also known to have been home to other carnivorous dinosaurs, albeit smaller than M. gigas, as well as other species of long-necked herbivores.
Canale said it’s usually very difficult to establish what dinosaurs ate, but loose teeth found at dig sites where herbivorous dinosaur fossils have been found have been matched to carnivorous dinosaurs.
This means we can say that M. gigas would have hunted, at least in part, such long-necked herbivores such as Argentinosaurus huinculensis, he added.
“It’s no coincidence that giant herbivorous dinosaurs and giant carnivorous dinosaurs lived in the same environments,” said Canale, who explained that as herbivores developed larger bodies as a form of defense, the carnivores did it too so they could go after them.
“There was a kind of arms race,” he said.
“No direct relationship” with T. rex
But the team says M. gigas evolved separately into T. rex and died out nearly 20 million years before T. rex walked on earth.
Canale said that although the two dinosaurs both have large heads and small arms, their bone structure is very different.
“There is no direct relationship,” Canale said.
M. gigas’ ancestors had longer arms and smaller heads, and their arms would have been important for hunting, Canale said, but that changed over time.
Previous research has found that dinosaur species such as M. gigas and T. rex developed smaller arms as their heads grew larger.
This shows that the weapons were not used for hunting, but rather they used their heads to kill their prey, Canale said.
“What I think is that in the most evolved forms… predation-related activities, like catching or holding the prey, would have been performed right away with the head,” he said. declared.
However, the fossil shows that although the arms were short, they were muscular and the chest muscles were also well developed, Canale said.
“It’s not consistent with a limb that has no function,” he said, adding that they could have been used to help get off the ground, or as a support on the female when lugging. ‘coupling. Researchers don’t know if this fossil belonged to a male or female dinosaur.
The team also found that M. gigas had ornaments such as ridges, furrows, bumps and small hornets on its skull, which were likely used to attract potential mates.
There is still work to be done on Mr. gigas, Canale said, and a colleague at the museum is writing a thesis on his feet and arms.
Additionally, there are plenty of fossils yet to be excavated in the area, as well as dinosaur footprints to be analyzed, he said.
“We have a lot of work ahead of us,” added Canale.
