How many tyrannosaurs have ever existed on Earth?

Scientists have recalculated the total number of tyrannosaurs (Tyrannosaurus rex) that have ever existed on Earth .

New research shows that 1.7 billion of these dinosaurs have existed throughout our planet’s history.

How many tyrannosaurs have ever existed on Earth?
There are about 1.7 billion T-rex that once existed on our Earth.

In April 2021, a study published in the journal Science estimated that as many as 2.5 billion T. rex individuals lived between 68 and 65.5 million years ago on Earth. But, according to new research, published in the journal Palaeontology, the actual number could be closer to 1.7 billion .

Study author Eva Griebeler, an evolutionary ecologist at Johannes Gutenberg University in Mainz (Germany), said the new model took into account information about T. rex that the authors of the original study overlooked. . That leads to a decrease in the number of calculated dinosaurs.

Charles Marshall, a paleontologist at the University of California, Berkeley (USA) and lead author of the 2021 study, said the new results are more comprehensive.

In the original study, Marshall’s team created a complex model that took into account a number of different variables. Variables included mean body mass, population density, approximate geographic range, reproductive age, number of eggs laid, average lifespan, survival rate, and generation time.

From there, to estimate how many T. rex can survive together. Modeling reveals that each generation of T. rex may include about 20,000 individuals. In addition, there are about 125,000 generations in the 2.5 million years they exist, which means a total of 2.5 billion T. rex.

However, researcher Griebeler disagrees with some of the data included in this model. She believes that Marshall’s team overestimated T. rex’s survival and spawning rates, as well as the number of generations that survived during this time. Those are the factors that skew the results.

Griebeler’s research shows that these values appear to be similar to those found in more modern birds and reptiles . When these values were fed into an updated model, it revealed that there were 19,000 individuals in each T. rex generation. Meanwhile, there are only about 90,000 generations, meaning the maximum number of T. rex in existence is 1.7 billion.

Regardless of the exact number, both studies raise an interesting question. That is: Where are all the T. rex bones? If Griebeler’s prediction is correct, that means we’ve only found fossils of 0.0000002% of these giant dinosaurs . According to both researchers Griebeler and Marshall, this is an important question that needs further investigation.