Paleontologists in North America estimate that the Earth has hosted 2.5 billion Tyrannosaurus rex in its history

2.5 billion from King Tyrannosaurus It is a large number. This number is what paleontologists in North America have come up with, according to their calculations about the existence of one of the most powerful predators on the planet.

The study revealed that it may be around 20,000 metric tons. Adult rex at any time, A plus or minus factor of 10, which falls within the range of what most researchers have assumed. According to lead researcher Charles Marshall, what few paleontologists have fully understood is that this means it About 2.5 billion lived and nearly died 2 and a half million years The dinosaur walked on Earth.

“The project started, in a way, just as a joke,” said Marshall, director of the UCSF Paleontology Museum, Philip Sandford Boone Chair of Paleontology and Professor of Integrative Biology and Earth and Planetary Sciences at the University of California, Berkeley. CWhen I have a fossil in my hand, I can’t help but wonder why it’s not likely that this same monster has been alive for millions of years. And here I am carrying a portion of his skeleton … seems very unlikely. The question that comes to my mind is: “How likely is this to happen? Is it one in a thousand, one in a million, one in a billion? Then I began to realize that maybe we can estimate the number of people who were alive and thus I can answer this question. “

Until now, no one has been able to calculate the numbers of long-extinct animals.

Marshall explained that the uncertainties in the estimates are significant. While the residents of ‘T. rex most likely from 20,000 adults at one time, 95% confidence range The population range in which there is a 95% chance of finding the true number – ranges from 1,300 to 328,000 individuals. Therefore, the total number of individuals who have been present throughout the life of the species could be between 140 million and 42,000 million.

The specialist said: “In our study, we focused on developing strong constraints on the variables that we need to perform our calculations, rather than focusing on providing the best estimates.”

Marshall notes that the biggest uncertainties in these numbers center around questions about the exact nature of dinosaur environment, including the score of T. Rex. The study is based on data published by John Damuth, of the University of California, Santa Barbara, Linking the body mass and the population density of live animals, a relationship known as Damoth’s law.

Although the relationship is strong, remember that environmental differences lead to large differences in the population density of animals that have the same physiology and ecological stature. For example, jaguars and hyenas are roughly the same size, but hyenas are found in their habitat at a density 50 times higher than that of leopards in their habitat.

Our calculations are based on this relationship of living animals between their body mass and population density, but the uncertainty in the relationship extends to two degrees of volume. “It is surprising that the uncertainty in our calculations is dominated by this environmental variability and not the uncertainty in the fossil data we use,” Marshall said.

The question of the place occupied by ‘T. rex ‘in the ecosystem led researchers to ignore juvenile specimens, which were not sufficiently represented in the fossil record and that, in fact, would have lived separately from adults and chased different prey. Like ‘T. rex ‘had reached maturity, and its jaws increased in strength, by order of size, This allowed him to crush the bones. This indicates that the young and the adults ate different prey and were almost like different predator species.

This possibility is supported by a recent study, led by evolutionary biologist Felicia Smith, of the University of New Mexico, which posits that the absence of medium-sized predators along with the T. rex ‘predator during the late Cretaceous period is due to the events occupying this ecological place.

Scientists at the University of Berkeley extracted from the scientific literature and the experience of their colleagues data that they used to estimate the likely age of sexual maturity of T. Rex 15.5 years old; Perhaps her maximum lifespan was until her late twenties; His average adult body mass – so-called environmental body mass – was around 5,200 kilograms, or 5.2 tons. They also used data on how fast a ‘T. rex’ has been throughout their lives: They’ve spawned a leap in sexual maturity and could weigh 7000 kg.

From these estimates, they also calculated that each generation lasted about 19 years and that the average population density was one dinosaur per 100 square kilometers.

Next, estimate that the total geographic distribution area of ​​’T. rex ‘was about 2.3 million square kilometers, and that the species had survived for nearly 2.5 million years, they calculated a permanent population size of 20,000. In a total of about 127,000 generations this species lived, that translates to about 2.5 billion individuals in total.

They wondered what, with so many post-event dinosaurs throughout the history of the species, let alone the most numerous events, where did all these bones go? To date, fewer than 100 individuals have been found, many of them represented by a single fossil bone.

“If we limit our analysis of the rate of fossil recovery to where T. rex ‘fossils are more common, which is part of the famous Hell Creek Formation in Montana, we estimate that we have recovered around it Of one in every 16,000 ‘T. rex’ that lived in that area During that period of time during which the rocks were deposited, “the researchers write.

“This number surprised us Marshall admitted, this fossil record contains a much higher representation of living things than I initially assumed. It could be as good as one in 1000, if you barely live there, Or it could reach one in a quarter of a million, given the uncertainty in the estimated population of the monster. “

And closed:With these numbers, we can begin to calculate the number of short-lived and geographically specialized species We might lose the fossil record. This may be a way to start identifying what we do not know. “

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