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MUSSAURUS

a plant-eating sauropodomorph dinosaur from the Late Triassic of Argentina.
mussaurus
Pronunciation: moo-SOR-us
Meaning: Mouse Lizard
Author/s: Bonaparte and Vince (1979)
Synonyms: None known
First Discovery: Santa Cruz, Argentina
Chart Position: 220

Mussaurus patagonicus

When Jose Bonaparte discovered what he believed to be the first remains of an all new critter during a trip to the Laguna Colorada Formation of Santa Cruz in the 1970s he promptly named them Mussaurus (rat lizard) because they were small, the largest being less than 40cm long. As it happens, his transliteration was off; "mus" actually means "mouse" in Latin, and they did sport rounded snouts and huge soppy eyes that could be described as mouse-like. But they were just hatchlings, seven in total, discovered in a "nest" along with a couple of eggs, and their features are typical of juveniles who cunningly use their cuteness to guarantee parental care.

By process of elimination, some paleontologists jumped to the conclusion that Mussaurus was merely a baby version of fellow sauropodomorph Plateosaurus, which is well-represented by numerous adult specimens from El Tranquilo, and the fact that they were nothing alike was simply because, well, kids and adults never are. A slight oversight on their part was that fully grown Mussaurus specimens had already been found in this exact area between 1962 and 1968 but, funnily enough, when Rodolfo Casamiquela described them in 1977 he thought they belonged to a new but un-named species of... Plateosaurus.

Mussaurus has short and high tail vertebrae which are absent in any currently known sauropodomorph but present in the Mid-Triassic La Rioja thecodont Lagosuchus which has been mooted as a possible ancestor of the Saurischia, and a skull with some characters similar to those found in a Late Jurassic macronarian sauropod known as Camarasaurus. Because they sport different features and their bone count ammounts to less, the troublesome youngsters were chopped from Otero and Pol's latest analysis altogether, but based on information garnered from the grown ups Mussaurus appears to dwell somewhere between the massospondylids and true sauropods on the sauropodomorph branch of the dinosaurian family tree.
(Mouse lizard from Patagonia)Etymology
Mussaurus is derived from the Latin "mus" (mouse) and the Greek "sauros" (lizard), so named for the tiny size and mouse-like features of the first specimens. However, adult individuals have since been discovered which renders "Mouse lizard" something of a misnomer. The species epithet, patagonicus, refers to its discovery in Patagonia.
Discovery
The holotype of Mussaurus (an almost complete juvenile skeleton catalogued as PVL 4068) was discovered during Jose Bonaparte-led Universidad Nacional de Tucumán and Fundación Miguel Lilloby joint expeditions at at "Estancia Cañadon Largo" in the Laguna Colorada Formation (El Tranquilo Group) of Santa Cruz Province, Patagonia, Argentina, in the 1970s, along with several other juvenile specimens. However, adult specimens had already been discovered in the same area between 1962 and 1968 by Casamiquela who described them in 1977, but he thought they belonged to Plateosaurus, and so did everyone else for the next 28 years. By 2005, the likes of Pol and Powell, and Salgado and Bonaparte, began to suspect that Casamiquela's specimens may actually represent adult Mussaurus, and their suspicions were confirmed with the discovery of yet more adults at the same locality.
Estimations
Timeline:
Era: Mesozoic
Epoch: Triassic
Stage: Norian
Age range: 228-209 mya
Stats:
Est. max. length: 3 meters
Est. max. hip height: 0.8 meters
Est. max. weight: 100 Kg
Diet: Herbivore
mussaurus-size.pngsize
Family Tree:
Dinosauria
Saurischia
Sauropodomorpha
Mussaurus
patagonicus
References
• Bonaparte J.F. and Vince M. (1979) "Discovery of the first nest of Triassic dinosaurs (Saurischia, Prosauropoda) from the Upper Triassic of Patagonia, Argentina".
• Casamiquela R.M. (1977) "The presence of the genus Plateosaurus (Sauropodomorpha) in the Upper Triassic of the El Tranquillo Formation, Patagonia".
• P. Dodson & B. Britt, K. Carpenter & C.A. Forster, D.D. Gillette & M.A. Norell, G. Olshevsky & M.J. Parrish, D.B. Weishampel (1994) "Mussaurus" in "The Age of Dinosaurs".
• Novas F.E. (2009) "The Age of Dinosaurs in South America".
• D. Pol and J.E. Powell (2007) "Skull Anatomy of Mussaurus Patagonicus (Dinosauria: Sauropodomorpha) From the Late Triassic of Patagonia". Hist Biol 19:125–144.
• Otero A. and Pol D. (2013) "Postcranial anatomy and phylogenetic relationships of Mussaurus patagonicus (Dinosauria, Sauropodomorpha)".
• I.A. Cerda, A. Chinsamy and D. Pol (2014) "Unusual Endosteally Formed Bone Tissue in a Patagonian Basal Sauropodomorph Dinosaur". The Anatomical Record. Volume 297, Issue 8, pages 1385–1391, 26 May 2014.
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To cite this page:
Atkinson, L. "MUSSAURUS :: from DinoChecker's dinosaur archive".
›. Web access: 27th Apr 2017.
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