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Billions of T. rex may have roamed the world, paleontologists report.



If you go back 67 million years ago to ancient Montana, you will enter the kingdom of tyrants: the iconic hunter. Tyrannosaurus RexBefore you enter that lost world, you may want to know how close it is on average. T. rex To you?

That may sound like something impossible to know. But after two decades T. rex New study research provides estimates of animal population densities. In all possibilities T. rex It will be no more than 15 miles from you.

The new study, published last Thursday in scienceAlso translate these population densities into estimates for the number T. rex Used to live On average, the researchers estimated that about 20,000 people. T. rex Lived at a particular time and about 1

27,000 dinosaurs lived and died. These averages represent 2.5 billion. T. rex It lives in the species’ continental North, which can be as far north as Alaska and as far as Mexico for a few million years.

This research is not the first time scientists have tried to evaluate it. T. rex Figures, in fact, the average population density in the new paper – about one T. rex Every 42 square miles – this is close to the previous estimate published in 1993, but the new study uses the latest data. T. rex Biological research to try to determine high-precision upper and lower limits for the entire population.

After millions of computer simulations, each with slightly different possible combinations, all studies have shown. T. rex The number could be as low as 140 million and as high as 42 billion, averaging about 2.5 billion the same everywhere from 1,300 to 328,000. T. rex May live at any time, with 20,000 being an average.

“It’s exciting to have someone try… use everything we know. T. rex “It’s interesting and fun that it hasn’t been involved in the new study,” said Hollywood Ward, a paleontologist at the Oklahoma State University Health Sciences Center. Have done this at this level. ”(Learn more about Woodward’s research on how T. rex Spent teenage years)

T. rex Accounting

Over the past 20 years, researchers have made numerous discoveries about T. rexThis includes a lifespan (approximately 28 years) at maturity (approximately 15.5 years) and weight when fully grown. (On average, about 15,000 pounds) these data for scientists to calculate. T. rexEstimated build time is 19 years given or received – and the average body mass of T. rex At any time

To go to T. rexThe researchers’ population numbers take advantage of the correlation between body mass and population density in live animals. On average, when body mass increases 10 times, the population density decreases by more than four-fifths, a pattern known as damat’s law.

Damuth, an ecologist at the University of California, Santa Barbara, discovered the pattern for the first time, collecting 30 years of ecological data on living mammals. However, Damuth’s Law is not a shield, as animals vary greatly according to specific lifestyles and habitats. For example, hyenas and jaguar found have similar body masses, and both are predators. But the population density of hyenas is 50 times higher.

When applied to T. rex (After editing according to the fact that T. rex Not a mammal) Damuth’s Law hints that the true total dinosaurs are likely to decline within 140 million and 42 billion individual dinosaurs.

“In the fossils it was very difficult to approximate things… so what I started was thinking less and more of estimating something about the bracketing it. Can I put a healthy upper and lower bound? ”Said lead author Charles Marshall, the study’s lead author, paleontologist at the University of California, Berkeley.

From life to stone

In addition to better understanding how many elephant-sized predators are trampling around, Marshall and his team were able to analyze the numbers to better assess how often fossils formed. Possibly of T. rex Figuring out the amount of fossils in the same way we can calculate the likelihood of a lightning strike?

There are hundreds of known examples. T. rexBut about two-fifths are in personal or commercial hands and cannot be reliably studied. Therefore, to determine the minimum total number of fossils for the purposes of the study, Marshall’s team limited the fossils to 32 post-juvenile fossils. T. rex Held in public institutions

If all T. rex That used to be alive – about 2.5 billion – gave those 32 fossils, then only 1 in 80 million. T. rex Fossils after they died Even though the animal’s fossil percentage is higher and we have yet to find the remains. But the uncertainty of these odds shows how rare it is for the remains to be buried quickly enough and in the optimum chemical conditions for mineralization and fossil formation. T. rex There is less than a thousand times in abundance if the total was not 2.5 billion, but 2.5. million– We may never have encountered it before, ”Marshall said.

The methods the Marshall team stated could be applied to other extinct species, too. Among the dinosaurs, researchers say one of the best choices was Cretaceous herbivores. MaiasauraIt is known by hundreds of samples, from newborn babies to adults.

For Woodward, one of the most exciting effects of the study is the really rare dinosaur fossils. If these rates hold for a species other than T. rexResearchers may be able to estimate how many dinosaurs did not turn into fossils – and are now irrevocably lost over time. How much we have, ”she said.




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