In order to estimate the population, paleontologists and teams of scientists must sum up all the research on Tyrannosaurus rex, and then combine ecological principles, which describe the relationship between population density and biological size.
According to the microscopic growth pattern in the bones, the researchers concluded that the age of Tyrannosaurus rex's first mating was around 15 years old. With the growth record, scientists can also generate a survival curve-the possibility that Tyrannosaurus Rex will live to different ages. Using these two numbers, the team of scientists estimated that the generation interval of Tyrannosaurus Rex was 19 years. Finally, Tyrannosaurus Rex has existed as a species for 1.2 to 3.6 million years. Based on all this information, we calculate that Tyrannosaurus Rex has existed for 66,000 to188,000 generations.
From the fossil record alone, we have produced the replacement rate of Tyrannosaurus Rex. If we can estimate the number of individuals in each generation, we can know how many Tyrannosaurus Rex once lived.
In ecology, there is a recognized relationship between body weight and population density, which is called Darmouth's law. Larger animals need more living space-a square mile of grassland can support many more rabbits than elephants. This relationship also depends on metabolism-animals that burn more energy need more space.
Paleontologists have put forward a series of good estimates of Tyrannosaurus Rex's weight, and also estimated its metabolic rate-slower than that of mammals, but faster than the modern large lizard family Modosaurus. According to Dartmouth's law, we estimate that there was a Tyrannosaurus Rex every 109.9 square kilometers in the ancient world. This is equivalent to having two in Washington, D.C. ..
Now we have all the parts we need. Multiplying the density by the area where Tyrannosaurus rex lived, we can estimate that there are 20,000 individuals in each generation.
Once we calculate the average population size, we can calculate the fossil rate of Tyrannosaurus Rex-the possibility that skeletal fossils will be discovered by humans after 66 million years. The answer is: about one in 80 million. In other words, every time humans find a Tyrannosaurus rex fossil, 80 million fossils disappear.
This figure highlights the incompleteness of the fossil record and makes researchers realize how rare it is that a species has not completely disappeared from the fossil record.
In addition to calculating the fossil rate of Tyrannosaurus rex, the new method can also be used to calculate the population of other extinct species.
Estimates of extinct animals always contain certain uncertainties. Our estimates of the population density of Tyrannosaurus rex range from 7 square kilometers to 1724 square kilometers. But surprisingly, the biggest source of this uncertainty is Darmouth's law. There are many variables in the existing animal cause method. For example, the mass of Arctic fox and Tasmanian devil Tasmanian devil is similar, but the population density of the latter is six times that of Arctic fox.
We also don't know the fossil rate of other extinct dinosaurs. If we find many fossils of some dinosaurs, does this mean that they are more common than Tyrannosaurus Rex, or that we just find their fossils more easily?
The latest research may reveal other hidden facts about the biology and ecology of Tyrannosaurus Rex.
For example, we may know whether the number of Tyrannosaurus rex fluctuates with the change of Triceratops+similar to the predation relationship between wolves and moose today.
If scientists want to apply this powerful estimation technique to other extinct animals, we need more excavation work.
Reference/How much-Tyrannosaurus Rex-Go Earth-15904 1