STL Science Center

STL Science Center

24 July 2018

Anatomy of A Mouse Lizard

The first article that appears in a Google Scholar search for Mussaurus is Pol and Powell's 2011 paper Skull anatomy of Mussaurus patagonicus (Dinosauria: Sauropodomorpha) from the Late Triassic of Patagonia. Starting off with the cranium is the right way to go (my research is concerned with the skull, in case anyone wasn't aware). Because there are so many specimens of Mussaurus known to us, there is a lot of the skeleton that is known as well; the head is just the beginning. In fact, Pol also helped to describe some of the postcranial anatomy as well (Otero and Pol, 2013). Like Pol, Mussaurus is known from Argentina, which partially explains why he has been involved in numerous papers on the small dinosaur including Cerda et al., 2014a, Cerda et al., 2014b, and Otero et al., 2017 in addition to the two mentioned above. These studies are all largely descriptions of anatomy, generally either skeletal or joint related. This is not the limit of studies on Mussaurus of course.

Mussaurus had its own profile in the 1993 book Age of Dinosaurs by Peter Dodson which briefly discussed all the details that were known of small dinosaur at that point. Many studies not describing skeletal or joint attributes directly have also been published on Mussaurus that rely heavily on those descriptions, a prime example being Montague, 2006 which generated estimates of body size for over 600 dinosaur species, including Mussaurus. Phylogenetic analyses have been conducted using these descriptions and anatomical characters also; see Upchurch et al., 2007. Lastly, we know that the nests have been described, notably in Bonaparte and Vince, 1979, the paper initially describing Mussaurus from juvenile and infant specimens found in the nest that forms the basis of the title and bulk of the paper. This occurrence of the first Triassic nest on record is significant beyond just the naming of Mussaurus of course. Dinosaur eggs have been known since at least 1923 when the American Museum of Natural History led expedition of Mongolia discovered supposed Protoceratops nests; these led to the naming of Oviraptor and eventually it was discovered that the nest belonged to Oviraptor rather than Protoceratops (another story for another day). This nest, that of Mussaurus, is one of the earliest known dinosaur nests and an important link in the story of dinosaur evolution. Also we can all agree that dinosaur nests are pretty cool and that the earliest dinosaur nests and their tiny occupants are also very cool.

Bonaparte, J.F. and Martin, V., 1979. El hallazgo del primer nido de dinosaurios triasicos,(Saurischia, Prosauropoda), Triásico superior de Patagonia, Argentina. Ameghiniana, 16(1-2), pp.173-182.
Cerda, I.A., Chinsamy, A. and Pol, D., 2014a. Unusual endosteally formed bone tissue in a Patagonian basal sauropodomorph dinosaur. The Anatomical Record, 297(8), pp.1385-1391.
Cerda, I.A., Pol, D. and Chinsamy, A., 2014b. Osteohistological insight into the early stages of growth in Mussaurus patagonicus (Dinosauria, Sauropodomorpha). Historical Biology, 26(1), pp.110-121.
Dodson, P., 1993. Age of Dinosaurs. Publications International Limited.
Montague, J.R., 2006. Estimates of Body Size and Geological Time of Origin for 612 Dinosaur Genera (Saurischia, Ornithischia). Florida Scientist, pp.243-257.
Otero, A., Allen, V., Pol, D. and Hutchinson, J.R., 2017. Forelimb muscle and joint actions in Archosauria: insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha). PeerJ, 5, p.e3976.
Otero, A. and Pol, D., 2013. Postcranial anatomy and phylogenetic relationships of Mussaurus patagonicus (Dinosauria, Sauropodomorpha). Journal of Vertebrate Paleontology, 33(5), pp.1138-1168.
Pol, D. and Powell, J.E., 2007. Skull anatomy of Mussaurus patagonicus (Dinosauria: Sauropodomorpha) from the Late Triassic of Patagonia. Historical Biology, 19(1), pp.125-144.
Upchurch, P., Barrett, P.M. and Galton, P.M., 2007. A phylogenetic analysis of basal sauropodomorph relationships: implications for the origin of sauropod dinosaurs. Special Papers in Palaeontology, 77, p.57.

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