Pampadromaeus

Chapter • Meet the dinosaur

Overview

Pampadromaeus barberenai was a small, lightly built, two-legged dinosaur that barely reached one and a half metres from snout to tail tip – and most of that length was neck and tail. Body mass estimates fall in the range of only a few kilograms, roughly that of a large rooster or a house cat. The skull was low and narrow with large eye sockets, and the teeth differed markedly along the jaw: the front teeth in the premaxilla were more conical and slightly recurved, while those further back were leaf-shaped with serrated edges. The neck was long and flexible, the arms short but with mobile hands and strong claws, and the hind limbs long and slender with elongated lower legs – a build associated in living animals with quick, agile movement. Like all sauropodomorphs, Pampadromaeus had scaly skin rather than feathers, and it carried its tail straight out behind it as a counterweight instead of dragging it. Pampadromaeus belongs to Sauropodomorpha, the same major dinosaur branch that later produced the gigantic four-legged herbivores such as Brachiosaurus and Diplodocus. In its own time, around 233–225 million years ago, the group was still small and lightweight. The animal is usually placed in the family Saturnaliidae together with its Brazilian relatives Saturnalia and Chromogisaurus, and it is precisely such forms that reveal what the sauropodomorph body plan looked like before the necks grew long and the bodies grew heavy. Most researchers read the mixed dentition as evidence of omnivory: Pampadromaeus probably ate both soft plant material and small animals such as insects and lizard-like reptiles. We do not know how Pampadromaeus behaved socially. The find consists essentially of a single individual, and there are no trackways or mass accumulations to show whether the animal moved in groups. Its locomotion is easier to reconstruct: the long hind limbs and short trunk indicate an active biped capable of short bursts of running, perhaps to catch prey or to escape the early predatory dinosaurs and large predatory crocodile relatives that shared its landscape. The holotype, catalogue number ULBRA-PVT016, was recovered at the Janner site near São João do Polêsine in the state of Rio Grande do Sul, southern Brazil, from beds of the Santa Maria Formation. The skeleton was nearly complete but disarticulated, which allowed many bones to be studied from every angle. The species was described in 2011 by Sérgio Cabreira, Cesar Schultz, Jonathas Bittencourt, Marina Soares, Daniel Fortier, Lúcio Silva and Max Langer. The name means roughly "pampas runner", after the South American pampas, and the species name honours the Brazilian palaeontologist Mário Costa Barberena. A detailed reassessment of the skull published in 2019 reinforced the interpretation of the animal as an early sauropodomorph.

Chapter • Where it lived

Habitat

Pampadromaeus lived in the Late Triassic (Carnian, about 233–225 million years ago) in what is now southern Brazil. The fossil comes from the Janner site near São João do Polêsine in Rio Grande do Sul, in the red mudstones and sandstones of the Santa Maria Formation. These beds were laid down on broad river floodplains with seasonally dry intervals, meandering channels and open, sparsely vegetated ground carrying conifer-like plants, ferns and seed plants. The same faunal horizon is rich in rhynchosaurs, cynodonts and early dinosaurs and dinosaur relatives, making the region one of the world's most important windows onto the earliest chapter of dinosaur history.

Chapter • Wild behavior

Behavior & Ecology

Did you know?

Chapter • Scientific place

Taxonomy