This Is How Many T-Rex Ever Existed

The Tyrannosaurus Rex. An iconic, instantly identifiable species. And according to a recent study, there were approximately 1.7 billion of them roaming the Earth prior to the asteroid that wiped them out.

A lot of factors had to be included to get this number, including average lifespan, sexual maturity and the amount of T-Rex eggs that survived.

While 1.7 billion is a large number, it is 800 million less dinosaurs that the estimate reached in 2021. 

"Unlike my model, the generation time as well as life expectancies, gross reproduction rates, and reproductive values of individuals calculated from the previous model all strongly contradicted our current understanding of the biology of T-Rex and of other theropods," Evolutionary ecologist Eva Griebeler from the Johannes Gutenberg University of Mainz in Germany said.

"Their values also disagreed with those of large extant reptiles, birds, and mammals. All of these shortcomings of the previous model favor the assessment of individual and population characteristics of T-Rex and of other extinct species using my model."

This new research was able to use updated models of T-Rex survival and maturity rates.

This new calculation shows a lower T-Rex survival rate, a reduced amount of egg-laying. This recent data factored on detailed fossil studies and comparisons with modern-species.

Griebeler tested her model against data on 23 different extant species among reptiles, birds, and mammals.

She found it predicted population numbers amazingly compared to the previous model, and it suggests it should work for the Tyrannosaurus Rex too.

This research also suggests humans have a minuscule percentage of the T-Rex remains.

Griebeler model focuses on maximum lifespan, sexual maturation age, and maximum annual offspring numbers and suggests this can also help estimate population numbers for other extinct species.

"All of these shortcomings of the previous model favor the assessment of individual and population characteristics of T. rex and other extinct species using my model."