Research shows how T. Rex’s eye evolved to deal with increased bite force
It seems as though Tyrannosaurus Rex and other mighty carnivorous dinosaurs might have developed smaller eyes as they evolved. So say researchers at the University of Birmingham. According to a new study, their eyes became more oval or elliptical while reducing in size to deal with the impact of crunching those jaws into their prey.
Herbivores retained circular large eyes while T.Rex changed to smaller eyes. The researchers say this is good, as an increase would have led to massive eyeballs that had to deal with too much stress. Here are more details on the matter.
Image credit: Dr Stephan Lautenschlager
Why T. Rex and other carnivores developed smaller eyes
In one of our recent news articles, we discussed a discovery as to why T. Rex and other similar carnivore dinosaurs had short arms while the skull increased in size. According to the University of Birmingham, that’s not the only evolutionary change that helped these hunters feast on their meals. Apparently, the bite force caused stress on the eyeballs if they were circular or large. As the skulls became larger over time, the eyes became smaller.
The scientific study
Dr Stephan Lautenschlageris is a Senior Lecturer for Palaeobiology. He performed a study at the University of Birmingham that involved analyzing the eye sockets of about 500 dinosaur species. What he found was interesting indeed, realizing a possible theory as to why carnivores had much smaller eyes with varying shapes towards the latter part of the Mesozoic era.
He published his findings in Communications Biology, which is where other researchers go to check new studies and confirm or dispute them. The details are similar to what I’ll summarize below, explaining why carnivores like T. Rex and Giganotosaurus had such small, oval eyes.
Herbivores were different
Part of his computations and analysis determined that herbivore dinosaurs had circular eyes. Of course, the larger the ancient beast was, the greater the eye socket’s diameter. You would think that a carnivore would have bigger eyes to hunt down its prey, but it appears not.
Dr Stephan Lautenschlageris indicates that there’s stress caused on the eyes while eating, especially when biting down into a hard surface. With T. Rex hunting down massive creatures with hardened skin or armor, he would need a massive bite force compared to a herbivore. If it had a large circular eye, that bite would cause severe strain on the eyeball.
Part of the study reveals that all of the carnivores he analyzed had either oval, elliptical, or key-hole eyes. It seems that those with larger bite force had smaller eyes, or a completely different shape. He theorizes that it may have been larger or more circular in the earlier period, but it evolved over time to deal with the impact of biting down on prey.
In Dr Lautenschlager’s own words:
“In these species, just the upper part of the eye socket was actually occupied by the eyeball. This also led to a relative reduction of eye size compared with skull size.”
It’s all in the looks
It’s definitely an interesting study into why T. Rex had such a massive head with small eyes. It really seems that the large skull had everything to do with the arms and eyes becoming smaller over time. I wonder how it managed to see so well, but perhaps it had better eyesight than others in this way, being able to home in on its target.