The Paleontologists of the California University calculated the number of tyrannosaurs, which lived in the chalk period, and received an approximate value of 2.5 billion individuals. At the same time, the land inhabited about 20 thousand adult predators. It was previously thought that to calculate the size of the population of extinct prehistoric animals is impossible. Results are published in the SCIENCE journal.
The assessment is based on the Damuta law, which binds the body weight of the form with the density of animal population. Although, with other things, equal relationship is very strong, environmental factors can affect the population, as well as niches that occupies. For example, with the same mass of the body of jaguars and hyenas, the latter form populations with a density of 50 times higher than the cat populations. That is why the uncertainty for the size of the tyrantosaurus population was two orders of magnitude.
Scientists have made that energy needs for the adult individual of the Tyrannosaurians lie in the middle between Lv and the Dresser Varan. From the calculation, young tyrannodosaurs were excluded, since they could differ significantly from more mature predators who have enough powerful jaws to crush the bones. According to modern views, the dinosaur had sex at 15 years old, the average mass reached 5.2 tons, and the life expectancy reached about 30 years. At the same time, a sharp increase in body weight occurs during the period of sexual maturity. For a change of generation, about 19 years left.
Scientists came to the conclusion that the average population density reached about one individual per hundred square kilometers, and the total area of habitat area is 2.3 million square kilometers. A total of 127 thousand generations of tyrantozavirov lived. This gives an approximate idea of how the remains of dinosaurs and other prehistoric animals are well preserved in the form of fossils: today there is less than one hundred tyrantovarov in the world, while only one bone remained. Thus, for every 80 million individuals account for only one – whose bones find scientists. It remains to guess how many geographically specialized and short-lived species of animals could be missed in the chronicles of fossils.
Nevertheless, the researchers emphasize that the uncertainty is quite high, and the range of the possible number of tyrannosaurs who lived in the whole chalome period varies from 140 million to 42 billion, and the whole population living at a certain point in time could achieve size from 1 , 3 thousand to 328 thousand individuals.