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T. rex had teenage growth – but not all dinosaurs did



But so far, it is not clear whether all dinosaurs shared this growth pattern. Was the period of extreme growth in the style of T. rex the only way for dinosaurs to become full-fledged adults?

A study of fossilized bone samples from 11 different dinosaurs, published Tuesday, found that while some transform during adolescent growth, others grow slowly and steadily.

Like tree trunks, dinosaur bones have rings that show how creatures have grown and aged.

“Most animals have a period each year when they stop growing, it is traditionally recommended to be in times like winter when food is scarcer. It appears in the bones as a line, like a ring on a tree,”

; said Tom Cullen, a research associate. on The Field Museum of Chicago and lead author of a new study in the Proceedings of the Royal Society B.

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“By analyzing these growth lines and examining bones for new growth regions, scientists can get a rough estimate of the animal’s age and how much it has grown each year. There is also evidence of bone structure,” he said in a news statement.

Researchers have found that dinosaur growth patterns depend on their family. T. rex and its relatives, celurosaurs, show a period of rapid growth during adolescence and then growth rate would peter after reaching adulthood.

However, the more distant cousins ​​of T. rex, according to the study, can reach a similar size, but grow more slowly.

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The team took bone samples from Carcharodontosaurus, a newly identified species from Argentina. Its size for adults reaches only 30 and 40 years and has lived to 50 or more years. Despite his advanced age, he had stopped growing only two or three years before becoming part of the fossil record.

For the study, Cullen also took a sample from the most famous dinosaur at the local Sue Museum T. rex. It has lived to about 33 years and is the most complete and best preserved T. rex.

Cullen uses a diamond-tipped drill to cut a battery-sized cylinder from Sue’s femur, a process he describes as a “nerve tear.”

Paleontologist Tom Cullen, a research fellow at the Field Museum in Chicago, cuts into T. Rex's Sue's femur to learn how the massive carnivore grew.

He then cut bone samples so thin that light could pass through them. This allows him to examine the samples under a microscope and analyze the lines showing where new bone has grown year after year. The missing part of Sue’s leg was filled with brown putty.

Mammals, including humans, tend to go through growth when they are young and then remain the same size once they reach maturity. This is not always the case with other animal groups.

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“The growth rate really varies, there’s no one size fits all,” said Cullen, who is now a postdoctoral fellow at the North Carolina Research Museum in Raleigh. (The museum announced last week that it is building the new SECU DinoLab to house and study the fossil pair of Triceratops horridus and Tyrannosaurus rex, which will be on display in 2022. The Dueling Dinosaurs are some of the most complete dinosaur skeletons ever found) which will contribute to further study of dinosaur biology.)

“Birds have super growth spurts and really reach adult size, while reptiles like alligators and various lizards and snakes prolong their growth. With them, a really, really big person is probably really old,” he added.

Rapid expansion can be an advantage, the study said, making it easier for other animals to hunt and harder for predators to hunt.

Conversely, accelerating growth takes a lot of energy and resources and it’s easier to just get a little bigger every year for the rest of your life.

“The amount of calories T. rex it would have to be ridiculous during its growth, “Cullen said.


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