Researchers have used a CT scanner to peer inside the hollow, fossilized skulls of a group of meat-eating dinosaurs that dominated the Jurassic Period, and found that the Tyrannosaurus rex had another advantage besides its size, speed, and pointy teeth–it also had an excellent sense of smell. Study coauthor Darla Zelenitsky says the scans show the impressions left on the skull by different brain regions, and says the T. rex had the biggest olfactory bulb, which regulates the sense of smell.
Zelenitsky says the findings suggest that the T. rex relied on smell extensively. “It’s probably fairly significant, because the sense of smell was likely used for foraging or searching for food,” Zelenitsky said. “And as well, it could have been used for patrolling relatively large home ranges. So, in that respect, it would have been a significant part of the biology and daily activities of the animal” [Calgary Herald].
Researchers say the results don’t settle the longest running debate about T. rex: whether it was a predator or scavenger. While some paleontologists have suggested previously that a keen sense of smell might indicate that T. rex was a scavenger who relied on its nose to find meals of rotting carrion, Zelenitsky says anatomical findings don’t support this theory. “While this makes it clear that that these species had a better sense of smell than other theropods of the time, it does not support any arguments that Tyrannosaurus was a scavenger, as there are both predatory and scavenging birds today with large olfactory bulbs,” says Zelenitsky [Nature News]. Predators find uses for a good nose, too, Zelenitsky says: For example, a predator T. rex could have hunted at night, and used smell to aid its strikes in the dark.
Other researchers have gotten inside the T. rex‘s head with CT scanners before and have noted the large olfactory bulb, but this is the first study to compare the size of the bulbs across species. In the study, to be published in Proceedings of the Royal Society B [subscription required], researchers performed CT scans on 21 species of the meat-eating dinosaurs, known as theropods, including huge predators, smaller raptors and ostrich-like dinosaurs [Reuters].
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Image: Royal Tyrrell Museum