Tyrannosaurus rex is the deserved "king of dinosaurs", and they are even larger than the largest terrestrial african elephant today! How many Tyrannosaurus rexes have ever survived on Earth? Paleontologists really figured it out!
T. rex is one of the large carnivorous dinosaurs with the most fossil preservation, and nearly a hundred individuals have been found so far, of which there are more than a dozen of them, which indicates that the number of Tyrannosaurus rex must be quite large.
Note: Fossils of Tyrannosaurus rex, picture from the internet
In order to find out the number of Tyrannosaurus rex populations, paleontologists at the University of California, Berkeley, began the study, led by Charles Marshall, a paleontologist who has always wanted to find answers. Marshall, along with Professor Philip Sandford Boone, director of the Paleontological Museum at the University of California, and his students, counted what is known as T. rex fossils, and then took into account factors such as T. rex sexual maturity, adult body size, and the energy needed by individuals to survive. According to damuth's law, body weight is an important variable related to the density of animal populations.
While focusing on T. rex itself, paleontologists have also noticed that differences in geographic environment can also directly lead to changes in animal population density, and the flatter and opener the terrain, the greater the number of large carnivores, the best examples being jaguars and spotted hyenas. The spotted hyenas that live on the open African savannah far outnumber mountain lions in populations, but the two are about the same size.
Image note: Spotted hyena on the prairie, picture from the internet
When these factors were statistically collated, the researchers used computer models to perform the calculations, where ecological variability is the largest variable that causes the calculation to deteriorate. In the end, the research team obtained data ranging from 140 million to 42 billion Tyrannosaurus rex, and after further calculations and analysis, the number of T. rex was determined to be 2.5 billion!
Illustration: T. rex population calculation model, picture from the paper
According to stratigraphic analysis, T. rex has a range of about 2.3 million square kilometers, and an adult T. rex needs about 100 square kilometers to survive, so the North American environment of the Late Cretaceous can carry 20,000 Tyrannosaurus rex at the same time. Tyrannosaurus rex lived 68 million to 66 million years ago, lasted for about 2.5 million years, and bred a total of 127,000 generations according to the time of the 19-year generation of Tyrannosaurus rex, so the total number of Tyrannosaurus rex is about 2.5 billion!
Caption: Adult T-Rex, image from the web
"If we had limited the fossil discovery rate to the place where the T. rex fossils were found, part of the famous Hell Creek Formation in Montana, we would have found 16,000 T. rex fossils, but that's not the case," Marshall said. This number is surprising, the fossil record's description of organisms is much higher than we initially thought, and in areas where fossils are often found, the fossil preservation rate may reach one in a thousand, while where no fossils are found, the rate is below one in a thousand. It is speculated that the Montana Hell Creek Formation may have lived in 250,000 Tyrannosaurus rex! ”
Image note: The ecological restoration of the Hell Creek Formation where the Tyrannosaurus rex survived, the picture comes from the network
In the process of research, Marshall may have ignored the location of juvenile Tyrannosaurus rex in the ecosystem, although the fossil record is small, but due to differences in body size, body structure, athletic ability, etc., juvenile Tyrannosaurus rex prey and prey are different from adult Tyrannosaurus rex, and this has been confirmed by the university of New Mexico evolutionary biologist Felicia Smith (felicia smith). In the ecosystems of Late Cretaceous North America, adult Tyrannosaurus rex occupied the position of top predators, while juvenile Tyrannosaurus rex occupied the position of high predator, feeding on smaller, agile swollen-headed dragons, oviraptorosaurs, ornithistorans, and so on.
Image note: Comparison of the body size of Tyrannosaurus rex of different ages, picture from the internet
Image note: The food of Tyrannosaurus rex of different ages is also different, and the picture comes from the internet
Although paleontologists have calculated the population of T. rex, this is based on more fossil discoveries and new technologies and methods that have emerged over the decades. Tyrannosaurus rex is one of the dinosaurs we know best, and the use of computer models to measure the number of paleontologists is just beginning to use. In the future, through continuous improvement, it is hoped that the number of paleontologists with shorter living ages and smaller geographical distribution will be calculated.
Related research was published in the recently published journal Science!
thesis:
c.r. marshall el al., "absolute abundance and preservation rate of tyrannosaurus rex," science (2021).
Image / Network (Intrusion and Deletion)
Text / Jiang's Little Thief Dragon (Jiang Hong)
Typography / Jiang's Little Thief Dragon