Research suggests that teenage Tyrannosaurus and other carnivorous dinosaurs may have crowded out smaller species like lions or bears, which explains why so few species are preserved in the fossil record.
Although dinosaurs have ruled the land for more than 150 million years, they are not particularly diverse, and most known species are giant animals weighing 1,000 kg or more, including giant carnivorous giant theropods such as Tyrannosaurus.
Particularly missing from the fossil record are small dinosaurs weighing less than 60 kilograms. This is very different from other vertebrate communities, which usually have a wide distribution of body types.
Now, a study published in the journal Science Provides an explanation: giant arthropods may have adopted a “rapid growth, young and dead”
To test this theory, Katlin Schroeder of the University of New Mexico and colleagues analyzed a data set of dinosaur records, which represents 43 geographically located communities across seven continents, spanning 136 million years. . This confirms that communities containing giant theropods basically do not have medium-sized carnivores in the 100-1,000 kg range, and those communities without giant theropods do contain these species.
Using existing information about the growth rate and age of death of these dinosaurs, they also calculated that juveniles must account for a large part of the total number of giant theropods, enough to outperform adult animals of similar size of different sizes.
Schroeder said: “Not only are there more juveniles than adults, but in this quality range that we lack from other species, they are correct.” These young theropods are likely to have occupied adult animals. An ecological niche-just like today’s Komodo dragons, their larvae hatch from eggs and scramble to climb trees, eat insects and lizards, until they grow too large and fall to the ground. Start hunting larger creatures, from rodents to buffaloes.
Schroeder said: “One thing about giant arthropods is that as they grow, they change a lot.” “An adult Tyrannosaurus This is a huge, sturdy, compact animal, but when they were young they were quite lightweight, down to earth, and did not have deep skulls. They may be the same genetic species, but they are completely different in appearance and function. “
Steve Brusatte, professor of paleontology and evolutionary chemistry at the University of Edinburgh, said: “This study provides us with data that we have long suspected but have not really confirmed: the largest carnivorous dinosaurs occupy different positions in the food chain because they have grown from micro-incubators to adult animals that are larger than buses.
“This seems to be a consistent pattern during the dinosaur reign, especially those in the Cretaceous period. There are few species of carnivorous dinosaurs of moderate size for adults. This is because juveniles, juveniles and sub-adults of bruised dinosaurs are controlling these. Wall ni. This is an ecological structure, very different from our habit of mammals today.”