Tyrannosaurus rex, one of the most feared predators in the dinosaur era, may have been built for endurance, not speed.
AN paper published Wednesday in the scientific journal PLOS ONE, recent research on how mammals move and apply it to dinosaurs. His conclusions support the theories that large carnivores hunt in packs and open a window to the ecology of the ancient forests that roamed.
"We are trying to find out how much energy enters and flows through paleo ecosystems," said Hans Larsson of McGill University in Montreal, one of the article's co-authors.
"If we can't get an estimate of what is needed to feed predators from the summit, we have no chance to estimate anything else."
To find out how much T. Rex needed to eat, scientists first had to figure out how he moved, including how fast he could run.
In the past, this was done using a formula based on hip height.
"This, combined with body mass, can tell us a lot about speed," said Larsson.
The problem is that an animal's speed comes from many factors – the relative length of certain leg bones; if it runs on the toes or the heels; and its size.
Consider the elephant. Its hip height is long, but a gazelle can wrap rings around it.
"Many other things come into play," said Larsson.
Recalibrating with a focus on body mass
"What we wanted to do was recalibrate … the speed of the dinosaurs, using some really cool roles that came up using mammals, especially really big mammals."
Larsson applied these roles to dinosaurs, bringing body mass to the calculation.
Previous articles have proposed that T. Rex could reach speeds of up to 70 km / h – a lightning pace for an animal that would weigh more than 10 tons. Larsson suggests that its upper end would be closer to 20 km / h.
But, he adds, T. Rex's long legs would have done 20 km / h very efficiently, a pace that could be maintained for a long time.
AN summary report The research notes that, for theropod dinosaurs weighing more than a ton, the maximum running speed is limited by body size; therefore, longer legs correlate with low-energy walking, while predators prowl for prey.
Larsson asked what that could mean.
Comparing pack animals
"If that was your way of hunting, being able to travel much greater distances with a very good clip, what kind of lifestyle would that be? The animals that do that today are those like wolves that hunt in packs."
Near Red Deer, Alta., A group of many meat-eating large dinosaur fossils appears to belong to members of a single herd.
"It is very good evidence," said Larsson.
Understanding how the main predator of Cretaceous-era forests moved and hunted allows scientists to ask better questions about this ancient ecosystem as well.
How much food would T. Rex need to move that immense body at this rate? How much prey would have to be available? What would that prey need to eat?
Answering these questions will have direct benefits for modern biology, said Larsson.
"Some of the fundamental questions about today's ecosystems still don't exist. In most cases, we don't even know what the food chain is."
Rebuilding an ancient food network from scarce fossil records could give science a roadmap for finding its way through the incredible complexity of a living forest, he said.
"We can start with a paleo ecosystem and start to develop ideas that can be used to start solving these issues in living ecosystems. The data becomes much simpler."