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When it came to the sense of smell among meat-eating dinosaurs, Tyrannosaurus rex nosed out the competition.
Scientists at the University of Calgary and the Royal Tyrrell Museum in Alberta, Canada, compared the size of their olfactory bulbs - the part of the brain regulating the sense of smell - in a wide range of carnivorous dinosaurs.
The researchers performed CT scans and measured fossilized skulls of meat-eating dinosaurs, known as theropods, including huge predators, smaller raptors and ostrich-like dinosaurs. They also looked at the primitive bird Archaeopteryx.
Tyrannosaurus, the scourge of North America at the end of the age of dinosaurs, was the undisputed king. Its olfactory capabilities surpassed that of the other huge predators the researchers examined, including South American giant Giganotosaurus and African killer Carcharodontosaurus.
"T-Rex had a very good sense of smell," Francois Therrien of the Royal Tyrrell Museum, one of the researchers, said in a telephone interview. "Probably that's how they located prey and patrolled a large territory."
The researchers were not the first to describe T-Rex's strong sense of smell, but were the first to rate the beast in comparison to other meat-eating dinosaurs.
Other experts have pointed to T-Rex's stellar smeller as evidence that it must have been more of a scavenger than an active hunter. Therrien disagreed.
"It has been suggested that the very good sense of smell of T-Rex indicated that it was a scavenger because it would have used its sense of smell to locate putrefying carcasses on the landscape," said Therrien, whose findings were published in the British journal Proceedings of the Royal Society B.
"But when we look at modern animals, we see that's not the case. Scavengers don't necessarily have a better sense of smell. You have some like the turkey vultures that have a good sense of smell. But you have other scavengers like the Old World vultures that actually have a typical sense of smell because they use sight instead of smell to locate prey."
Vicious little Velociraptor and its raptor relatives also had an excellent sense of smell, the researchers said. But the ostrich-like dinosaurs like speedy Ornithomimus and the toothless Oviraptor apparently had very poor senses of smell.
Archaeopteryx, the earliest known bird with fossils dating to 150 million years ago, turned out to have a good sense of smell in line with that of the small meat-eating dinosaurs from which paleontologists believe birds evolved, they said.
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