No, they weren’t all giants. Some dinosaurs were small. They even got smaller and smaller. For example the dinosaurs that ate ants. This is the case with the unusual alvarez dinosaurs.
The new work is led by Zichuan Qin. He is a student at Bristol University and the Department of Paleontology in Beijing. He measured the height of dozens of specimens. In this way he showed that for most of their life they weighed between 10 and 70 kilos, the size of a large turkey to a small ostrich. And 100 million years ago they quickly reached the size of a chicken. At the same time, they adopted a new diet: eating ants.
Alvarez dinosaurs lived 160 to 70 million years ago. They were slender, two-legged predators for most of their existence. They had lizards, mammals, and baby dinosaurs for food.
“Perhaps competition with other dinosaurs intensified during the Cretaceous.” That is what it says in a statement by Professor Michael Benton of the Bristol School of Earth Sciences. “It was a time of rapidly evolving ecosystems. Flowering plants completely changed the nature of the landscape. However, most of the dinosaurs did not feed on these new plants. But they caused an explosion of new species of insects, including ants and termites.
This restructuring of ecosystems has been known as the Cretaceous Revolution. Forests and insects emerged that pollinated the new flowers.
“Heights rose and fell during the first 90 million years of its existence. The average was 30 to 40 kg,” says Zichuan. “95 million years ago his size suddenly dropped to 5 kg. The shape of his claws changed from grasping and cutting to hit.
“All the other dinosaurs kept getting bigger. But a group of carnivores has been miniaturized. It was the dinosaurs that ate ants. And over time, they became birds.