It is common in many animals for the growth of the young to follow a specific rhythm, which does not vary much from one individual to another. However, faced with a shortage of food, the young can suffer serious developmental disorders and die. Dinosaurs of the species Massospondylus carinatus had a very flexible growth cycle, according to the results of recent research.
The Massospondylus was a medium-sized dinosaur, weighing up to 500 kilograms, that lived in the early Jurassic, that is, about 200 million years ago. It fed on plants such as ferns.
By looking at the fossil thigh bones under the microscope, researchers can count the growth rings, comparable to the annual growth rings of a tree. This allows them to find out how much the studied animal grew each year.
By observing the growth rings in Massospondylus carinatus bones, the team at Kimberley Chapelle, the American Museum of Natural History in New York City, and the University of the Witwatersrand in South Africa, have been able to show that their growth varied from season to season. to another, more like a tree than a cub or a human baby.
“One year they could gain 100 kilograms of body weight and the next year they could only grow 10 kilograms,” says Chapelle. “
Reconstruction of a Massospondylus carinatus. (Image: Dorling Kindersley)
The study suggests that the growth of Massospondylus responded directly to environmental conditions. In a good year, with plenty of rain and food, the baby would grow a lot, for example to almost double in size. In a bad year, in which the nutrients were scarce, it hardly grew.
Chapelle and his colleagues suggest that this growth strategy may have helped Massospondylus cope with the harsh environmental conditions that followed the Late Triassic Mass Extinction 200 million years ago, when more than half of the species succumbed. (Source: NCYT from Amazings)