- T. rex is often described as the king of all killing machines, but some scientists question that description.
- According to one theory, T. rex was too clumsy and slow to do its own hunting.
- Given other dinos that were around at the time, one researcher argues, T. rex couldn't have survived on scavenging along.
Palaeontologists fought back on Wednesday in a spirited debate over the Tyrannosaurus rex, saying revisionists who branded the great dinosaur a shameless scavenger have got it all wrong.
For more than a century after its discovery, many scientists routinely described the Tyrannosaurus as the king of the killing machines -- six tons of teeth, muscle and sinew, designed to run down dinos several times its size and shred them.
But over the last decade, a new wave of T. rex scholarship has painted another, less flattering, picture.
T. rex, according to this theory, was just a 12-meter (40-foot) freeloading lizard that was too clumsy and slow to do its own hunting.
It simply barged in on a meal after nimbler predators had done all the dirty work -- in other words, it was more hyena than lion.
The first broadside on the carnivore's predatory credentials came in 2003, when American expert Jack Horner concluded that T. rex's clawless forearms, beady eyes and lumbering legs meant it was "100 percent scavenger."
In 2007, John Hutchinson of the Royal Veterinary College in Britain dished out another blow, demonstrating the "clunky" dinosaur needed more than two seconds to pivot 45 degrees, making it easy for would-be prey to evade capture.
But a new study, published in the Proceedings of the Royal Society B: Biological Sciences, may help redress the balance.
Chris Carbone of the Zoological Society of London and colleagues say that some of the traits that raised doubts about T. rex's predatory prowess are larded with ambiguity.
An enhanced sense of smell, inferred from enlarged olfactory bulbs, is a common trait among scavengers such as vultures -- but it can help a hunter too, they note.
T. rex's eyes, it turns out, are not that small after all, and its binocular vision -- along with its crushing bite and impact-resistant teeth -- are all well adapted for killing.