In Depth
Saturnalia is today considered to be a sauropodomorph, albeit a very primitive one at that. The fossil record concerning the evolution of dinosaurs is still very incomplete and quite possibly will never be known as a whole, but as soon as dinosaurs appeared in the Triassic period it seems that it was only a relatively short time before saurischian (lizard hipped) dinosaurs had already split into its two main groups; the Theropoda and the Sauropodomorpha. Those who know their dinosaurs will already know that while the theropods remained one of the key groups throughout the history of the dinosaurs, the members of the sauropodomorpha would steadily evolve into the true sauropods that would become one of the largest and most dominant types of plant eating dinosaurs by as quickly as the middle Jurassic.
Saturnalia was a long way from such gigantic dinosaurs as Diplodocus and Brachiosaurus, yet the basic body form of these later dinosaurs can already be seen in sauropodomorphs like Saturnalia. The necks of sauropodomorphs in particular were already starting to lengthen so that an individual could feed upon a greater range of plants without actually having to physically move the body. Also, although the forelimbs were still shorter than the rear limbs, they still seem to have been capable of bearing weight. Combined with the long length of the actual body (not including neck or tail), it seems that in a normal resting posture Saturnalia was probably more likely to be quadrupedal, a fore shadowing of future descendants that would have been mostly quadrupedal. Saturnalia itself however may have still been capable of rearing upon just its hind legs to gain further reach when feeding and may have run on just two legs when escaping predators.
The exact diet of Saturnalia is a little uncertain due to its basal placement within the Sauropodomorpha. Future sauropods would be exclusive herbivores, but they were descended from ancestors that were meat eaters. The skull and hands of Saturnalia show more classic theropod features, and the vast majority of the genera that belong to this group, especially during the Triassic, are confirmed meat eaters. It is not entirely impossible that Saturnalia might have incorporated small organisms or even scavenged meat into its diet, yet it may also have already switched to a more plant exclusive diet.
The discovery of a partial femur (thigh bone) of Saturnalia in Zimbabwe can be taken as further evidence that South America and Africa were once joined together, something that allowed for the free exchange of fauna between the two continents. A possible predator of Saturnalia might have been Staurikosaurus, a slightly larger theropod dinosaur that is also known from the Santa Maria Formation of Brazil.
Further Reading
A sauropodomorph dinosaur from the Upper Triassic (Carnian) of southern Brazil, M. C. Langer, F. Abdala, M. Richter & M. Benton - 1999.
