Temporal range: Late Cretaceous
An artist's illustration of A. calvoi
Scientific classification
Kingdom: Animalia
Phylum: Chordata
clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Alvarezsauridae
Subfamily: †Alvarezsaurinae
Genus: Alvarezsaurus
Bonaparte et al., 1991
Species: A. calvoi
Binomial name
Alvarezsaurus calvoi
Bonaparte et al., 1991

Alvarezsaurus (meaning "Alvarez's lizard") is a genus of small alvarezsaurid dinosaur from the Late Cretaceous Argentina from 86 to 83 ma. It was found in the Bajo de la Carpa Formation. The type species is A. calvoi, and is the only known species of the genus so far.


Alvarezsaurus was a small theropod with a single claw on each hand, a long tail, and a very feathery coat. Its leg structure also suggests a lifestyle of fast running, either used for evading predators or chasing prey; it is unknown which of these two uses the speed was prioritized for. Estimates measure the creature at about 2 meters (6.5 ft) in length and weighed approximately 20 kg (45 lbs).

Given its morphology and related genera, it was likely an insectivore, but may have also hunted small animals as well.


After being named by paleontologist José Bonaparte in 1991, it was placed in the family alvarezsauridae (being the namesake of the family). Other related members include Mononykus and Shuvuuia, but Alvarezsaurus is considered more basal than the rest. It has also been classified in the same clade that includes all birds and ancestors of birds, being maniraptora.

In popular culture[]

  • Alvarezsaurus was originally supposed to appear in the movie Disney Dinosaur but was cut and it's concept art is shown.
  • Alvarezsaurus was featured in the Discovery Channel television series Dinosaur Planet, where it was presented as a predator of young Saltasaurus and a sharp-eyed predator that also lusts for eggs. However, these genera did not coexist, Alvarezsaurus being approximately 5 million years older than Saltasaurus.
  • Alvarezsaurus appeared on Dinosaur Train as an illustration.


External links[]

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