How can the bite of this little ground finch be more powerful than a T. rex's?

January 11, 2019, 8:20 a.m.
The large ground finch has a comparatively more powerful bite for its body size than a T. rex.
Photo: Lip Kee Yap/Wikimedia Commons

The large ground finch's bite is bigger than its chirp — or a T. rex's bite, for that matter.

That's the news from an analysis published in the Royal Society journal Proceedings B that looked at bite forces across evolution. The tiny Galapagos large ground finch, which weighs just over 1 ounce (33 grams) has a bite force of 70 Newtons, an impressive showing for such a lightweight animal. The T. rex, by comparison, weighed around 8 tons and had a bite force of 57,000 Newtons, which is merely average for a creature of that size.

This makes the finch's bite 320 times more powerful, pound-for-pound, than the T. rex's.

"The image of T. rex with its fierce jaws has helped it become the most iconic of dinosaurs, but our research shows its bite was relatively unremarkable," Manabu Sakamoto, biological scientist at the University of Reading and lead author of the study, said in a statement. "Bite force was not what gave T. rex its evolutionary advantage, as was previously presumed.

"Large predators like T. rex could generate enough bite force to kill its prey and crush bone just by being large, not because they had a disproportionately powerful bite. This counters the idea that an exceptionally strong need for a powerful bite drove these ancient beasts to evolve bone-crushing bite forces."

Sakamoto and his colleagues used supercomputers to match the bite force data from more than 400 species, both living and extinct, across the animal kingdom. The researchers were attempting to determine whether or not animals with more powerful bites were forced to evolve more rapidly in that manner due to their diets.

Instead, researchers found that the bite power of many animals developed proportionally to the changes in their body size over time. Only in a few instances did the bite force develop faster than other changes. Sometimes these changes took a while, like the T. Rex's bite took tens of millions of years to evolve. The finch evolved its bite in less than 1 million years, according to the researchers.

In the case of human beings, our bite force decreased rapidly as our brains grew.

"Once we learnt to cook food, bite power became even less important," Sakamoto said. "In effect, we evolved the cooking pot as our way of making our food easier to swallow. This is in line with other studies showing that humans chew their food less than other animals."

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