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According to scientists who analyzed slices of fossilized bones, large carnivorous dinosaurs reached their great size through very different growth strategies, with some taking a slow and steady path and others experiencing a teenage growth spurt.
The researchers examined annual growth rings – similar to those in tree trunks – in the bones of 11 theropod species, a large group that encompasses all large carnivorous dinosaurs, including Tyrannosaurus Rex and even birds. The study provides insight into the lives of some of the most fearsome predators to ever walk the Earth.
The team examined samples from museums in the United States, Canada, China and Argentina and even received permission to cut bones from one of the most famous in the world. T. Rex fossils, known as Sue and housed at the Field Museum in Chicago, using a saw and diamond-tipped drill.
Sue’s leg bones – a huge femur and fibula – helped illustrate this T. Rex and his relatives – known as tyrannosaurs – experienced a period of extreme growth during their teens and reached full adult size by around 20. Sue, who measured about 13 meters, lived about 33 years.
Sue inhabited South Dakota about a million years before dinosaurs and many other species were wiped out by an asteroid impact 66 million years ago.
Other groups of large theropods tended to have more constant growth rates over a longer period of. That growth strategy was detected in lineages that arose around the world at the beginning of the dinosaur era and subsequently concentrated on the southern continents.
Examples included Allosaurus is Acrocanthosaurus from North America, Cryolophosaurus from Antarctica and an as yet unnamed species from recently discovered Argentina that rivaled T. Rex to an extent. The Argentine dinosaur, from a group called carcharodontosaurs, did not reach its full adult size until age 40 and lived to be around 50.
Congratulations to the lab alum @ cullen_thomas, lt; / a, gt; & amp; @ PeteMakovicky, lt; / a, gt; on an interesting new history article: T. rex had a teenage growth boom – but not all dinosaurs did – CNN https://t.co/n1eXXcTGbK,lt;/a,gt;
& mdash; @DavidEvans_ROM
Large theropods share the same overall body design, walk on two legs, and boast large skulls, strong jaws, and menacing teeth.
“Before our study, it was known T. Rex grew very rapidly, but it was unclear whether all theropod dinosaurs reached gigantic sizes in the same way, or if there were multiple ways to do so, “said paleontologist and lead author of the study Tom Cullen of the North Carolina Museum of Natural Sciences. and North Carolina State University, also affiliated with the Field Museum.
The research was published this week in the journal Proceedings of the Royal Society B.
“Theropod dinosaurs represent the largest bipedal animals that have ever lived and have also been the dominant predators in terrestrial ecosystems for over 150 million years – more than twice as long as mammals have been dominant,” said the University of Delphi paleontologist. Minnesota and study co-author Peter Makovicky.
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