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This article comes from the official account of Wechat: SF Chinese (ID:kexuejiaodian), author: SF

Original title: "how long can dinosaurs live?" The answer is beyond the expectations of scientists. "

Through dinosaur fossils, scientists can learn a lot about dinosaurs. This picture shows scientists based on fossils, the scene of a fight between a dinosaur and Protoceratosaurus. (photo Source: Raul Martin) We are all too familiar with dinosaurs. What dinosaurs looked like, what dinosaurs ate, how dinosaurs hunted, what environment dinosaurs lived in, and even why dinosaurs became extinct. Even children can talk about similar questions about dinosaurs. We already know so much about dinosaurs, but there is a problem that many people may not understand or even think about: how long dinosaurs can live.

(Steve Broussart (Steve Brusatte) / tr. by Robert Taylor)

Editor | Zhao Jiaming

Paleontologists once believed that dinosaurs grew so big because they lived for a long time, with an average of more than 100 years, and like crocodiles and iguanas, dinosaurs grew slowly and continuously all their lives. But now we know that this is not the case. Most dinosaurs grow fast and die when they are young.

How to judge the life span of dinosaurs? The life span of dinosaurs was also obtained by studying fossils. The fossilized bones of dinosaurs are cut open and the growth lines are counted so that scientists can judge the age of dinosaurs and then speculate on the life span of dinosaurs. As we all know, the age of trees can be judged by their rings. Like trees, dinosaur bones form a "ring" every year.

Every year a tree grows, the trunk grows in a circle, which is called a ring. The same is true of dinosaur bones. Scientists can judge the age of dinosaurs by studying the "rings" of fossilized dinosaur bones. (photo source: Dietmar Rabich / Wikimedia Commons / "D ü lmen, Hausd ü lmen, Baumwurzel-2021-7057" / CC BY-SA 4.0) in this way, we know that Tyrannosaurus rex takes 16-22 years to reach adulthood and usually dies at 27-33; another large carnivorous dinosaur, shark-toothed dinosaur, lives between 39 and 53 years. Sauropod dinosaurs with long necks, such as leptosaurus and Diplodocus, seem to have a similar lifespan to sharktooth dinosaurs, and some sauropods live to the age of about 70.

The life span of dinosaurs seems to be so different from what we think. How can such extraordinary dinosaurs have such an ordinary life span? Even compared with the lifespan that paleontologists once guessed, the lifespan of several decades is slightly shorter. Some friends may ask, what factors affect the life span of dinosaurs? What causes dinosaurs to live only a few decades?

Why didn't dinosaurs live too long? The first factor affecting the life span of dinosaurs is the growth pattern. Animals have two growth patterns: unrestricted growth and limited growth. Some animals grow all their lives, and as long as they live for one day, the growth will not stop. This growth pattern is unrestricted growth. On the contrary, it is limited growth.

As mentioned earlier, dinosaurs, like iguanas and crocodiles, grew all their lives and therefore belonged to animals with unlimited growth. In the animal kingdom, animals with unrestricted growth usually have a longer life span. By comparing living animals with unrestricted growth, scientists have speculated the lifespan of various types of dinosaurs: small dinosaurs can live for 30 to 40 years, medium-sized sauropod dinosaurs can live for 80 to 110 years, and large dinosaurs can live for more than 100 years.

This is still a far cry from the life span of dinosaurs judged by scientists through "annual rings". What factors make dinosaurs that should have lived a long life become short-lived?

The first is metabolism. In general, thermostats with higher metabolic levels live shorter lives than thermostats with lower metabolic levels. Seeing this, friends may say that dinosaurs belong to reptiles, reptiles should be warm animals, life should be longer ah. In fact, scientists have found that most dinosaurs are thermostat animals, so higher metabolic levels reduce the life span of dinosaurs.

In the age of dinosaurs, the poor living environment made many dinosaurs not live long. (photo source: Nobu Tamura) second, the environment also has an impact on the life span of dinosaurs. Dinosaurs lived in an era when the environment was suitable for dinosaurs, but it was still bad compared with the earth today: the amount of oxygen in the atmosphere, the amount of sulfur oxides in the atmosphere and water, and the amount of radiation from the universe were all very different from what they are now. Such a harsh environment, coupled with the hunting and competition among dinosaurs, many dinosaurs will die if they don't live long.

All in all, dinosaurs didn't live very long. How can such an ordinary life span make dinosaurs become the overlord of the Mesozoic era and dominate the earth for about 140 million years? This needs further research by scientists.

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