PARIS (AFP) - Tyrannosaurus Rex could sniff out distant prey even at night, yet another reason the flesh-ripping predator reigned supreme as king of the dinosaurs, according to a study published Wednesday. Earlier research had shown that the towering T-rex could see better than an eagle and would have been able to run down the fastest of humans. The new study now unveils a previously unheralded weapon in the fearsome theropod's arsenal: a dangerously keen sense of smell. Any trace of the brains of dinosaurs, which roamed Earth for tens of millions of years up to the end of the Cretaceous Period 65 million years ago, has long since disappeared. But a trio of scientists led by Darla Zelenitsky at the University of Calgary in Alberta, Canada found a novel way to gage the sniffing prowess of T-rex and a couple dozen other meat-eating dinosaurs and primitive birds. By examining fossil skull bones, the researchers were able to measure the size of indentations made by olfactory bulbs, the part of the brain associated with the sense of smell. "Living birds and mammals that rely heavily on smell to find meat have large olfactory bulbs," Zelenitisky said in a statement. The same animals also tend to prowl for prey at night, and cover vast areas, he added. Of all the dinosaurs examined, the T-rex had the largest olfactory bulb relative to its overall size. The study, published in the British journal Proceedings of the Royal Society B, also found that primitive birds had high-performance odor detectors, challenging a long-held assumption about the evolution of winged vertebrates. "It has been previously suggested that smell had become less important than eye sight in the ancestors of birds, but we have shown that this wasn't so," said Zelenitsky. Archaeopteryx, for example, which took to the skies during the Jurassic Period some 150 million years ago, had a sense of smell comparable to meat-eating dinosaurs along with excellent eye sight, the study said. Somewhere along the way birds began to lose their sense of smell, but the decline probably happened far later than previously thought, the study concludes.