The reason for the arms of the tyrannosaurus

Why did they have them like this? What is the reason for the tyrannosaurus' arms being so small and useless? This was analyzed for a long time. Researchers at UCL (University College London) and the University of Cambridge in the United Kingdom thought about it. The evolution of tiny arms in several groups of carnivorous dinosaurs was probably driven by the development of strong, powerful heads. These were used to attack prey. The important study is in the journal 'Proceedings of the Royal Society B'.

They thus evolved to use their heads as a better weapon.

Attack method

Data from 82 species of theropods (bipedal dinosaurs, mainly carnivorous) were analyzed. Forelimb shortening was found to occur in five groups. Including tyrannosaurids, the family to which Tyrannosaurus rex belonged.

It turns out that smaller arms were closely related to the development of large, strong skulls and jaws. It has nothing to do with a larger body size in general. Small arms were not simply a byproduct of increasing body size.

The increase in the size of prey, in the form of giant sauropods (herbivores with long necks and tails) and other large herbivores, played a role. It led to a shift towards hunting using the jaws and head instead of claws. Several giant theropod dinosaurs also evolved relatively small forelimbs. The Carnotaurus had ridiculously small arms. Smaller than those of T. rex. There was a strong relationship between short arms and large, robust heads. The head replaced the arms as the method of attack.

The reason for the Tyrannosaurus's arms is in food.

Arms that disappeared

The arms were no longer useful. They reduced in size over time. These adaptations usually occurred in areas with gigantic prey. Trying to grab and hold a 30 meter long sauropod with your claws is not ideal. Attacking and holding with the jaws could have been more effective. Robust skulls most likely preceded shorter forelimbs. It would make no evolutionary sense for it to happen the other way around.

The team claimed that the presence of increasingly gigantic prey could have led to an "evolutionary arms race." Theropods developed strong skulls and jaws to better subdue these prey. In many cases, they themselves reached gigantic sizes. The reason for the arms of the Tyrannosaurus and others of its time is in food.