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A species of moderately small dinosaurs, the Mussaurus belongs to the group of dinosaurs from the woodlands of the South American continent. Having lived approximately 215 million years ago, the dinosaur belonged to the upper Triassic period. It was one of the ancient prosauropods. Mussaurus fossils were found in the country of Argentina.

The discovery of Mussaurus fossils
The fossils of the Mussaurus were discovered in the formation known as ‘Argentine el Tranquillo’ in the early 1970s. No adult specimens or skeletal fossils were found at the time. The interesting fact was that the fossils also consisted of newly hatched fossils and unhatched eggs. These are some of the smallest dinosaurian fossils known to man. The type species of the Mussaurus is the M. patagonicus.

The Triassic Period
The Triassic period is the first period of the Mesozoic Era. It stretches from approximately 250 to 210 million years ago. The Triassic period is preceded by the Permian and succeeded by the Jurassic period. The only landform during the Triassic was the supercontinent of Pangaea, which began to split in half during the very end of the Triassic
The Triassic period comprises of three geochronological sub-periods, namely the Lower, Middle and upper Triassic. The Upper Triassic period is also known as the Late Triassic. It extended from 228 to 201.3 million years ago. The upper Triassic formations have produced rich varieties of dinosaurs all over the world. The end of the Upper Triassic is marked by an extinction of half the living species on the planet. This event is known as the Triassic Jurassic extinction event.

The place of discovery of the Mussaurus fossils
The Mussaurus fossils were discovered in the Santa Cruz province of Argentina. Rocks belonging to the late Triassic period, dating to approximately 228 to 200 million years ago are found in abundance in the el Tranquilo formation. The rocks comprise of prehistoric sandstone deposits. Other than the Mussaurus, the fossils of a few other sauropods and prosauropods have been found in this formation. The formation has been subject to constant excavation expeditions by Jose Bonaparte and his colleagues.
Jose Bonaparte is considered to be a pioneer and the father of paleontology in Argentina. He has discovered and identified several prehistoric dinosaurs. He is the senior scientist of Natural Sciences Museum, Argentina. He has successfully discovered and identified over at least 25 different species of dinosaurs including Riojasaurus, Antetonitrus, Coloradisaurus and Guabisaurus among others.

Physical Characteristics of the Mussaurus
The Mussaurus is a moderately large dinosaur, contrary to the name which suggests it is a small dinosaur. The adults of the species whose fossils were later found are believed to have measured up to three meters in height and weighed about a 100 kilograms. The infant fossils discovered were barely inches long, measuring about 20 to 30 centimeters. This appearance of these infantile fossils has been found to bear resemblances to mice.
The eggs found at the earlier site of discovery measured up to a maximum of 1inch in length. Like all other known sauropods, it had a long neck that allowed it to feed on the large pines and ferns that grew in the southern continent. It had significantly strong and sturdy thigh bones. The lower limbs were longer than the upper limbs. The hands consisted of five separate digits, with the thumb having a large claw.
The head of the adults was small, whereas those of the juveniles of the species was tall in proportion to the rest of the body. The tail was broad where it attached to the hip and then tapered towards the posterior. The brain to body weight ratio, like other sauropodomorphs is significantly small, meaning the creature had a low intelligence. The teeth were sharp and fused to the jawbone. The back had a moderate convex curvature. The eyes of the infant fossils were large whereas those of the adults were narrow.

Related dinosaur species
The dinosaur species is most closely related to the Coloradisaurus, amongst other known sauropodomorphs. The species were earlier assigned to the Plateosaurus dinosaurs. Some scientists also speculated that the infant fossils actually belonged to the Coloradisaurus. It was only when the adult fossils were discovered that these speculations were put to rest and then the fossils were classified under a separate group.
Paleontologists Pol and Otero conducted a cladistics analysis in 2013. In this study, data was taken from only the adult specimens to determine the phylogenetic relations with other Plateosaurian dinosaurs. Cladistics uses the biological classification in an effort to find the relationship between individual species based on common ancestry.

About the Mussaurus fossils
The Mussaurus lived in the arid deserts of the present day country of Argentina. It was an herbivorous creature meaning it fed on the tall spruces and pines and other leafy vegetation. The Mussaurus was half quadruple, meaning that even though it used to walk on all fours, it had the ability to stand on just its hind legs while eating the leaves off large pines.
A terrestrial animal, the creatures are believed to have moved through the South African continent in herds. This ensured safety and subsequent survival of their species. Assumptions have been rife about whether the Mussaurus was a sauropod or a prosauropod. For now, the creature has been placed in the Sauropodomorpha.
The unearthing of the infant fossils and unhatched eggs of the Mussaurus have helped partially understand and determine the reproductive and nesting behavior of these reptiles. It is a very significant landmark in the history of paleontology. Scientists have discovered that more than one egg belonged to the same parent dinosaur, meaning there is a possibility of multiple births.
The Mussaurus is an important dinosaur as far as the discovery of fossils is concerned. This “rat reptile” from the Triassic can help us answer a lot of questions. A lot about this dinosaur still remains uncertain. More stringent analysis of the fossils will help us determine this creature’s role in the prehistoric ecosystem.