Apr 16, 2021 10:40:00

It is estimated that 2.5 billion Tyrannosaurus have lived on the earth so far.

Tyrannosaurus is a large carnivorous dinosaur that lived mainly in North America during the late Cretaceous of the Mesozoic era , from about 68 million years ago to about 66 million years ago. A research team at the Museum of Paleontology at the University of California reports that the total population of Tyrannosaurus in about 2.4 million years is more than 2.5 billion.

Absolute abundance and preservation rate of Tyrannosaurus rex | Science
https://science.sciencemag.org/content/372/6539/284

Two and a half billion T. rex dinosaurs once lived, study finds --Axios
https://www.axios.com/t-rex-billion-dinosaur-population-estimates-study-bbee965b-268c-4afc-9dc7-f9f9901ab080.html

New Tyrannosaurus rex study shows 20k lived at any one time, or 2.5 billion in total
https://www.psychnewsdaily.com/new-tyrannosaurus-rex-study-shows-20k-lived-at-any-one-time-or-2-5-billion-in-total/

Dinosaur fossils are limited in number and have not been found enough to estimate species populations. Therefore, the research team predicted the population of Tyrannosaurus based on the 'Dams' Law' that 'the larger the body size, the lower the population density'.

According to the research team, the average weight of Tyrannosaurus was about 5200 kg. Applying this value to Dams' Law, the population density of Tyrannosaurus was calculated to be 'one per 40 square miles'. This population density means that there are about 6 Tyrannosaurus inhabiting the area of Tokyo's 23 wards.

Then, by multiplying the estimated area of the tyrannosaurus habitat by this population area, it was estimated that up to 20,000 tyrannosaurus lived in one generation. Furthermore, from the lifespan of Tyrannosaurus, it is considered that Tyrannosaurus lasted about 127,000 generations in 2.4 million years, so it is calculated that a total of more than 2.5 billion Tyrannosaurus lived on the earth so far.

However, 'the accuracy of the relationship between body weight and population density is uncertain and the analysis is not very accurate,' said Charles Marshall, author of the paper and senior researcher at the Museum of Paleontology, University of California. According to Mr. Marshall, the total population of Tyrannosaurus is only an estimate, and in reality it is within the range of 140 million at the minimum and 42 billion at the maximum.

Nonetheless, the research team can now estimate the total population of Tyrannosaurus as a framework for estimating extinct populations, and even estimate the number of species that may have been missed in fossil excavation. I expect it to be.

'The results of this study also make it possible to estimate the number of short-lived species that lived in only a small area. We know the estimation method we have developed. It could be a way to quantify what isn't there. '