Mussaurus
Encyclopedia
Mussaurus was a genus
of herbivorous prosauropod dinosaur
that lived in southern Argentina
during the Late Triassic
Period, about 215 million years ago. It gets its name from the small size of the skeletons discovered so far.
However, since Mussaurus is known only from fossil
ized juvenile and infant skeletons, it is something of a misnomer; adults possibly reached 3 m (10 ft) in length, and weighed 70 kilograms (154.3 lb). 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.
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.
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.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of herbivorous prosauropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
that lived in southern Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
during the Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
Period, about 215 million years ago. It gets its name from the small size of the skeletons discovered so far.
However, since Mussaurus is known only from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
ized juvenile and infant skeletons, it is something of a misnomer; adults possibly reached 3 m (10 ft) in length, and weighed 70 kilograms (154.3 lb). 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 BonaparteJosé Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
during the 1970s to the El Tranquilo Formation
El Tranquilo Formation
The El Tranquilo Formation is a geologic formation dating to roughly between 228 to 200 million years ago and covering part of the Late Triassic. The El Tranquilo Formation is found in the Santa Cruz province of Argentina. Purported fossils of the prosauropod dinosaur Massospondylus have been...
. 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 cm (7.9 to 14.6 in) long. This is about the size of a small 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.