Mussaurus
muss-SORE-us
"mouse lizard"
Type species Mussaurus patagonicus
- Lived
- 200 to 193 million years ago, Early Jurassic
- Length
- about 3 m (10 ft)
- Found in
- Argentina
- Named by
- Bonaparte and Vince 1979
Size comparison
To scale
Scale in metersOutline: typical early sauropodomorph shape
Where its fossils were found
The evidence
Today
195 million years ago
Habitat
Its nesting grounds lay beside a lake in a dry landscape. Windblown dust buried eggs and skeletons in fine sediment that became part of the Laguna Colorada Formation.
Field notes
About Mussaurus
What it was like
Mussaurus was a plant eater from the line that led to the giant sauropods. Its name comes from its first fossils: tiny hatchlings small enough to fit in a hand. Later finds showed that adults were much larger, and about 3 meters (10 feet) long is a common estimate.
Young Mussaurus seem to have walked on all fours, then shifted onto their hind legs as they grew.
Its world
It lived in the Early Jurassic, in what is now Argentina. Its fossils come from the Laguna Colorada Formation. Some finds include groups of eggs and young animals of similar age, which suggests Mussaurus nested in colonies and may have lived in herds.
How it was found
Bonaparte and Vince named Mussaurus in 1979. The type species is Mussaurus patagonicus. It is now known from many specimens, from eggs to adults, which makes it one of the best studied early sauropodomorphs.
Field gallery
More views of Mussaurus
Scenes reconstructed from the available fossil evidence.
1 of 3
The evidence
The science behind Mussaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- Eggs, embryos, hatchlings, juveniles and adult skeletons preserve a broad sequence of growth.
- Groups of young animals of similar age were buried together, while adults occur separately or in pairs.
- Preserved egg coverings were interpreted as soft shells.
Borrowed from relatives
- Much of its body is known from its own bones at different ages, so its changing proportions need little borrowing from relatives.
Still unknown
- Its color and skin pattern.
- How much care adults gave their hatchlings.
- Which plants it preferred to eat.
Discovery timeline
- 1979Named itBonaparte & Vince
- 2019Growing upOtero et al.
- 2020Growing upNorell et al.
- 2021Fossil sitesPol et al.
Key papers
The research behind what we know of Mussaurus
Named it
Named Mussaurus from tiny young skeletons found together near fossil eggs.
El hallazgo del primer nido de dinosaurios triasicos, (Saurischia, Prosauropoda), Triasico Superior de Patagonia, Argentina [The discovery of the first nest of Triassic dinosaurs (Saurischia, Prosauropoda,) from the Upper Triassic of Patagonia, Argentina]. Ameghiniana 16: 173-182
No link available
Growing up
Models of hatchlings, juveniles and adults suggest that growth shifted its balance backward, allowing a change from four-legged standing to two-legged walking.
Ontogenetic changes in the body plan of the sauropodomorph dinosaur Mussaurus patagonicus reveal shifts of locomotor stance during growth. Scientific Reports 9
Read the paper : Ontogenetic changes in the body plan of the sauropodomorph dinosaur Mussaurus patagonicus reveal shifts of locomotor stance during growth (opens in a new tab)Growing up
Examined preserved egg coverings and concluded that Mussaurus and Protoceratops laid soft-shelled eggs.
The first dinosaur egg was soft. Nature 583: 406-410
Read the paper : The first dinosaur egg was soft (opens in a new tab)Fossil sites
Eggs and skeletons grouped by age suggest repeated nesting and herd life, with young animals gathering separately from adults.
Earliest evidence of herd-living and age segregation amongst dinosaurs. Scientific Reports 11
Read the paper : Earliest evidence of herd-living and age segregation amongst dinosaurs (opens in a new tab)
Close relatives
Other members of Sauropodiformes
Sources: Wikidata