Scientists explain why some dinosaurs have shrunk
In a new study, scientists found that alvaressaurs quickly shrank to the size of chickens. It turned out that it was all about their diet: at some point, dinosaurs only ate ants.
Alvaressaurs lived in many parts of the world – they inhabited China, Mongolia and South America. This dinosaur species lived in the period from the Late Jurassic to the Upper Cretaceous (from 160 to 70 million years ago). They were slender bipedal predators who spent most of their time on Earth feeding on lizards, the first mammals, and the offspring of other dinosaurs.
“Competition with other dinosaurs probably intensified in the Cretaceous. The Cretaceous period was an era of rapidly evolving ecosystems, and the biggest change was the gradual conquest of land by flowering plants. They changed the nature of the landscape and led to the active growth of various species of insects, for example, ants. Dinosaurs didn’t eat new plants, but they did eat ants, ”said Professor Michael Benton.
Initially, alvaressaurs were not small in size and were not even anteaters. Their ancestors, such as Haplocheirus, were relatively large dinosaurs, about the size of a small ostrich, with sharp teeth, flexible forelimbs, and large eyes. All of this suggests that before the dinosaurs began to consume only ants, their diet was mixed.
Scientists’ calculations have shown that the body weight of alvaressaurs has decreased from 30-40 kg to 5 kg in 95 million years. Also, due to the diet, the shape of their claws has changed.