Eating dinosaurs defends themselves by growing fast

Without a hard shell like iron to protect the body, plant-eating dinosaurs are forced to increase their body sizes to survive. In adulthood, they grow faster than carnivorous dinosaurs at least three times.

In the 10th year of life, the body length of Hypacrosaurus stebingeri - a plant-eating dinosaur - reaches 9 m from the nose to the tail tip. Meanwhile, the body length of tyrant Tyrannosaurus rex is relatively modest when they reach the same age. Their bodies only reach that length when they are between the ages of 20 and 30 years.

According to scientists at Kent State University (USA), the size difference forces predators to attack unborn adults Hypacrosaurus stebingeri .

Lisa Noelle Cooper, a doctoral student at Kent State University, said: 'When a Hypacrosaurus stebingeri reaches adulthood, I think it won't be afraid of predators. But when Tyrannosaurus rex's body reaches its maximum size (about 12 m), that's not true anymore. '

Hypacrosaurus (left) has a faster rate than Tyrannosaurus rex carnivores (Photo: LiveScience)

Cooper and her colleagues compared data on the evolution of Hypacrosaurus stebingeri with three predatory dinosaurs. They all lived in the late period of White Pollen - 65 to 100 million years ago.

For the Hypacrosaurus stebingeri , Cooper's team analyzed their leg bones and counted their growth rings (about one year each in life). The dinosaur Cooper studied at age 13 when he died.

'The Hypacrosaurus stebingeri grew three to five times faster than carnivorous dinosaurs of its age. When the leaf-eating animal grows fully, the body of the new Tyrannosaurus rex reaches its maximum size. That is a big difference in size. '

Hypacrosaurus also entered the estrus age earlier, in the second or third year of life, the researchers said.

'It is a beneficial point in survival warfare with predators. If the plant-eating dinosaurs were killed, the Hypacrosaurus species would not fall into extinction, because the females would have given birth to other children. '