Close up of "Sue" - one of the most complete T.rex fossils ever found. Researchers have used the skeleton to develop models that show the dinosaurs may have grown bigger and faster than previously believed.
Credit: ScottRobertAnselmo/wikimedia
CHICAGO: The iconic Tyrannosaurus rex may have grown even bigger than previously estimated, and at a faster rate, new models have shown.
Using actual skeletons rather than scale models, British and U.S. scientists digitally modeled flesh on five mounted T. rex skeletons.
Their findings, published in the open access journal PLoS One, show that the fearsome meat-eaters were up to one-third bigger and grew upwards of twice as fast into adults than previous research had suggested.
"We estimate they grew as fast as 3,950 pounds (1,790 kilograms) per year during the teenage period of growth, which is more than twice the previous estimate," said lead author John Hutchinson from the Royal Veterinary College, London.
Studying Sue
One of the skeletons included in the study was "Sue," the largest and most complete T. rex specimen ever found, on display at The Field Museum of Natural History in Chicago.
The 67-million-year-old dinosaur was discovered in 1990 in South Dakota by American palaeontologist Sue Hendrickson.
Named after its finder, "Sue" was previously thought to be about the size of a big elephant or rhinoceros, standing 3.5 metres tall and stretching 13 metres from head to tail.
Bigger than previously believed
Her living weight was guessed to be around 6,400 kilograms, or about six tonnes. But the latest methods for modelling growth found she would have tipped the scales at well over nine tonnes.
"We knew she was big but the 30 percent increase in her weight was unexpected," said co-author Peter Makovicky, curator of dinosaurs at the Field Museum in Chicago.
The technique used mounted skeletons to derive body mass estimates, instead of models created to scale.
The team made three-dimensional laser scans of the skeletons to form a template for digital models that would add simulated flesh.
Skeletal models more accurate
They devised three different levels of the approximate amount of flesh the creatures likely had, to figure the size of a thin, hungry animal up to a well-fed one.
"Previous methods for calculating mass relied on scale models, which can magnify even minor errors, or on extrapolations from living animals with very different body plans from dinosaurs," said Makovicky.
"We overcame such problems by using the actual skeletons as a starting point for our study."
By establishing new sizes for the other four specimens studied, the researchers also found that the creatures likely grew faster than initially thought, adding roughly five kilograms per day during their peak growth spurt.
The same team had estimated in 2004 that T. rex gained only 2.1 kilograms per day.
