A Tyrannosaurus rex would have had great
difficulty getting its jaws on fast, agile prey, according to a
2007 study. A US team used detailed computer models to work out
the weight of a typical 'king of the dinosaurs', and to determine
how it ran and turned.
The results indicated that a 6-8 tonne T rex
was unlikely to have topped 40km/h (25mph) and would have taken a
couple of seconds to swivel 45 degrees. The researchers reported
their findings in the Journal of Theoretical Biology.
They built on previous work detailing the
biomechanics of the famous dinosaur, but added in new refinements.
The team found they had a pretty good estimate of its weight -
over which there had previously been some controversy according
to lead author Dr John Hutchinson. He and his colleagues were able
to show that there was no way it could weigh 3-4 tonnes as some
people had suggested. It had to have weighed between 6-8 tonnes.
The team's computer modelling system estimated
the centre of mass position and the inertia (resistance to turning),
both of which had ramifications for how T rex would have
stood and moved and what it would have looked like. As well as
predicting the dinosaur's likely body mass and top speed (25-40km/h
or 15-25mph), the computer calculations gave the team an idea of
the turning ability of a T rex. This had never before been
The study indicated that the animal would have
changed direction incredibly slowly due to its massive inertia,
taking one or two seconds to make a quarter-turn. The species
certainly could not have pirouetted rapidly on one leg, as
popular illustrations have sometimes pictured it and other large
dinosaurs doing. More agile prey would have given the slip to a
marauding T rex quite easily, it seems.
The researchers believed that their work would
help palaeontologists build up a more realistic picture of how
the large dinosaurs lived. These were big, rather clunky things
- T rex and also the animals it probably preyed on. The
perceived view of that ecosystem needed to be slowed down. It
wasn't like the Serengeti today, where everything is done at top
Dr Paul Barrett, of London's Natural History
Museum, commented that this was another finding that undermined
the idea of T rex as a super-predator. The main reason
for that is that it was a lot slower than we used to think it
was; but it has this huge mouth filled with sixty-odd, 30cm-long
teeth, so it was still a formidable animal.