Saturnalia

Chapter • Meet the dinosaur

Overview

Saturnalia tupiniquim was a small, lightly built dinosaur that would barely have reached an adult human's knee at the hip. It measured roughly 1.5 to 1.8 metres from snout to tail tip, much of that length being the slender tail, and weighed somewhere between 6 and 11 kilograms. Its neck was slightly elongated compared with the very earliest dinosaurs, the skull was small and low, and the arms were noticeably shorter than the hind limbs. The hand bore five fingers with a stout thumb claw, a feature that would become a hallmark of later sauropodomorphs. Its skin was almost certainly scaly; no feather-like structures are known from this branch of the dinosaur family tree. The body was held horizontally, with the tail carried clear of the ground as a counterweight. Saturnalia walked and ran on two legs. Long lower leg bones and a light torso point to an agile, fleet-footed animal well equipped to escape the predators of its world, including early carnivorous dinosaurs such as Staurikosaurus and Herrerasaurus, as well as large crocodile relatives. Three individuals were recovered close together in the same rock layer, which has been read as a hint that the species at least occasionally moved in small groups. It was probably active by day, foraging across seasonally dry plains and among stands of conifers and ferns. The jaws and teeth of Saturnalia are especially revealing. The front teeth are narrow and slightly recurved, like those of a meat-eater, while the teeth further back are leaf-shaped and coarsely serrated in the way typical of plant-eaters. Most researchers therefore interpret Saturnalia as an omnivore standing close to the transition from the ancestral carnivorous dinosaurs to the herbivorous sauropodomorphs. Its meals probably included soft plant material, insects, small reptiles and other easy pickings. The fossils were found in 1998 at the Waldemar Jud site just outside the city of Santa Maria in Rio Grande do Sul, southern Brazil. The species was described the following year, in 1999, by Max Langer, Fernando Abdala, Martha Richter and Michael Benton. The name Saturnalia refers to the Roman midwinter festival, because the bones were excavated during the Brazilian carnival season, while the species name tupiniquim is a Brazilian expression meaning "native" and honours the Tupi people. Today Saturnalia is one of the key fossils for understanding what the lineage that eventually produced giants such as Brachiosaurus and Argentinosaurus looked like at its very beginning.

Chapter • Where it lived

Habitat

Saturnalia lived in the Late Triassic, during the Carnian stage about 233 million years ago, in what is now the state of Rio Grande do Sul in southern Brazil. All known specimens come from the Alemoa Member of the Santa Maria Formation, specifically the Waldemar Jud site near the city of Santa Maria. At the time the region lay deep inside the supercontinent Pangaea, and the landscape consisted of broad river floodplains with strongly seasonal rainfall, temporary watercourses and open woodland of conifers, horsetails and ferns. Saturnalia shared this world with rhynchosaurs, dicynodonts, early cynodonts and some of the very first predatory dinosaurs.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy