Alvarezsaurus is a type of dinosaur that lived during the Late Cretaceous period, around 86 to 83 million years ago. This small dinosaur was discovered in Argentina.
Alvarezsaurus measured about 1 to 1.4 meters long, which is around 3.3 to 4.6 feet. It weighed approximately 3 kilograms, similar to the weight of a small dog. The name “Alvarezsaurus” means “Alvarez’s lizard,” and it was named after a historian named Don Gregorio Alvarez by the paleontologist José Bonaparte in 1991. The specific type of Alvarezsaurus is called A. calvoi.
This dinosaur walked on two legs, which makes it a bipedal theropod. Its long tail helped it with balance, and its body shape suggests that it was a quick runner. The structure of its tail and backbones shares similar features with other dinosaurs in its family, known as alvarezsaurids, like Shuvuuia.
Alvarezsaurus had a unique leg structure where one of the toe bones, called metatarsal III, was the longest. It might have eaten insects, making it insectivorous.
In terms of its classification, Alvarezsaurus is seen as a more primitive relative of better-known dinosaurs like Mononykus and Shuvuuia. Some scientists have debated whether alvarezsaurids are related to modern birds, but the evidence is still being studied. In fact, new fossils from China showed that there are even older relatives of these dinosaurs.
Overall, Alvarezsaurus was a fascinating small dinosaur with many unique features that help scientists understand the diversity of life on Earth millions of years ago.