Mussaurus

*Mussaurus patagonicus*

**Mussaurus** (meaning "mouse lizard") was a genus of herbivorous prosauropod dinosaur that lived in southern Argentina during the Late Triassic Period, about 215-195 million years ago. It gets its name from the small size of the skeletons discovered so far. However, since Mussaurus is known only from fossilized juvenile and infant skeletons, it is something of a misnomer; adults possibly reached 3 meters (10 feet) in length, and weighed 70 kilograms (150 lbs).

Mussaurus possesses anatomical features suggesting a close, possibly transitional evolutionary relationship with true sauropods.Its evolutionary significance and the light it sheds on prosauropod reproduction make Mussaurus a significant find.

## Discovery

The fossils were first discovered by an expedition led by Jose Bonaparte during the 1970s to the El Tranquilo Formation. There the team found fossilised eggs and hatchlings, which added insight into the reproductive strategies of Mussaurus and other prosauropod dinosaurs.

Although the specimens' young biological age gave them proportions that would be highly atypical for an adult prosauropod, that they were indeed prosauropods was easily ascertained by examination of the limbs and pelvic bones.

## Reproduction

Mussaurus specimens have been found in association with nests that are believed to contain multiple eggs apiece. The skeleton of Mussaurus infants was small, only six inches long excluding the tail, but a total of 20 to 37 centimetres (7.9 to 15 in) long. This is about the size of a moderately sized lizard. Juveniles differed from adults in proportion in addition to size and mass. As is common for dinosaurs, juvenile Mussaurus had tall skulls with short snouts and large eyes.

These proportions are common in many infant vertebrates and are often associated with species that parental care during the vulnerable early stages of life. Adults are expected to have longer snouts and necks, and to look more like one would expect of a prosauropod.

## Social Behavior

Research Suggest this species lived in social groups compromised of adults and juveniles.

## JPInstitute.com Description

The first Mussaurus ever discovered was that of a very small baby. It lived in the Triassic Period, making it one of the earliest dinosaurs, and is believed to belong to the family of dinosaurs from which the huge sauropods eventually evolved. Mussaurus was totally unlike its huge descendants, however, as it was a small, fast plant-eater.

Mussaurus was found in the mid 1970s and named in 1979 by Jose Bonaparte and Martin Vince. Mussaurus got its name because the first specimens found were babies in a nest and they were about the size of a mouse. Since then, sub-adults and adults have been found that scientists believe are the same species. These specimens show that Mussaurus grew to around 10 feet long. At the time of Mussaurus' discovery, very few dinosaur babies and nests had been found. A lot of information about dinosaur social behavior and the rearing of their young resulted from their discovery. Mussaurus were prosauropods and are thought to hold clues to the origins of the sauropods.

## Links

http://web.archive.org/web/20030216023917fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_mussa.html#

## References

1. ↑ https://www.nature.com/articles/s41598-021-99176-1