Aratasaurus museunacionali: New Feathered Carnivorous Dinosaur Found in Brazil

Wednesday, July 15, 2020

Life reconstruction of Aratasaurus museunacionali. Image credit: Maurilio Oliveira.

Paleontologists have announced the discovery of a new genus and species of coelurosaurian dinosaur, Aratasaurus museunacionali, from the Romualdo Formation in the Araripe Basin, Brazil.

Aratasaurus museunacionali roamed the Earth during the Cretaceous period, approximately 104 million years ago.

The new dinosaur was a type of coelurosaur, a large group of small, lightly built, theropod dinosaurs which are more closely related to birds than to carnosaurs.

Its remains were recovered from the Romualdo Formation, which is known worldwide for the large number of well-preserved fossils.

The fossil material is preserved in a dark shale slab with originally 1.2 m by 0.8 m (3.9 by 2.6 feet), and a thickness of around 3 cm (1.2 inches).

Aratasaurus museunacionali is known by an incomplete but articulated right hind limb with the distal portion of the femur, proximal half of tibia and incomplete pes,” said senior author Dr. Alexander Kellner from the Laboratory of Systematics and Taphonomy of Fossil Vertebrates at the Museu Nacional/Universidade Federal do Rio de Janeiro and colleagues.

The holotype of Aratasaurus museunacionali, showing the femur and tibia before preparation. Scale bar – 10 cm. Image credit: Sayão et al, doi: 10.1038/s41598-020-67822-9.

The bones showed that this Aratasaurus museunacionali specimen was a juvenile, with an estimated body length around 3.12 m (10.2 feet) and a body mass of 34.25 kg.

The extinct creature is closely related to Zuolong salleei, a coelurosaurian dinosaur that lived some 160 million years ago (Jurassic period) in China.

“The material known from Aratasaurus museunacionali differs from derived coelurosaurian groups (e.g. Tyrannosauroidea, Ornithomimosauria) and Megaraptora mainly regarding by the cnemial crest and the disposition and morphology of metatarsals,” the paleontologists said.

“Among basal coelurosaurs, the new Brazilian theropod has a tibia similar to that of Zuolong salleei, and the pes more similar with that of Aarun zhaoi and Tanycolagreus topwilsoni.”

“The new taxon represents the first occurrence of basal coelurosaurians in the Araripe Basin and suggests a widespread distribution of this group during the Lower Cretaceous,” they said.

The discovery of Aratasaurus museunacionali is reported in a paper in the journal Scientific Reports.


J.M. Sayão et al. 2020. The first theropod dinosaur (Coelurosauria, Theropoda) from the base of the Romualdo Formation (Albian), Araripe Basin, Northeast Brazil. Sci Rep 10, 10892; doi: 10.1038/s41598-020-67822-9