''Mussaurus'' (meaning "
mouse
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia al ...
") is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
of
herbivorous
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
sauropodomorph dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
that lived in southern
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...
during the Early Jurassic, with a maximum age of 192.78 ± 0.14 Ma.
It receives its name from the small size of the skeletons of juvenile and infant individuals, which were once the only known specimens of the genus. However, since ''Mussaurus'' is now known from adult specimens,
the name is something of a misnomer; adults possibly reached in length and weighed more than .
''Mussaurus'' possesses anatomical features suggesting a close, possibly transitional evolutionary relationship with true sauropods.
Discovery

Infant and juvenile fossils of ''Mussaurus'' were first discovered by an expedition led by
Jose Bonaparte during the 1970s to the
Laguna Colorada Formation.
["Mussaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forste]