''Aratasaurus'' (meaning "lizard born of fire") is a monotypic genus of

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

coelurosauria Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, ty ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ...

which includes a single species, ''Aratasaurus museunacionali'', known from

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

found in deposits of the

Romualdo Formation The Romualdo Formation is a geologic Konservat-Lagerstätte in northeastern Brazil's Araripe Basin where the states of Pernambuco, Piauí and Ceará come together. The geological formation, previously designated as the Romualdo Member of the ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. ''Aratasaurus'' lived during the

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± ...

stage of the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

(111-108 Ma; possibly as early as 115 Ma).

Discovery and naming

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

, MPSC R 2089, was discovered in a plaster mine in 2008, and the holotype fossil was taken to the

Plácido Cidade Nuvens Museum of Paleontology Placido may refer to: People Surname * José Plácido de Castro (1873–1908), Brazilian soldier and politician * Michele Placido, (born 1946) Italian actor and director *Plácido Vega y Daza, (1830-1878) 19th century Mexican general and politicia ...

to be prepared and described. Between 2008 and 2016, microscopic analyses of the tissues of the holotype were made using small samples of the bones. Also in 2016, the holotype was taken to the

National Museum of Brazil The National Museum of Brazil ( pt, Museu Nacional) is the oldest scientific institution of Brazil. It is located in the city of Rio de Janeiro, where it is installed in the Paço de São Cristóvão (Saint Christopher's Palace), which is ins ...

; on September 2, 2018, the museum was heavily damaged in a fire, but the area where the holotype was stored remained intact. In 2020, the holotype was described as the new genus ''Aratasaurus''. Only the right hind limb was collected, although more of the skeleton was probably present but not collected. The generic name came from the Tupi words "''ara''" and "''atá,''" meaning "born" and "fire," and the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

"''sauros,''" meaning lizard; together meaning "lizard born of fire." The specific name references the

, a science institution, which was devastated by a fire in 2018.

Description

The holotype fossil material consists of an incomplete right limb, including a partial

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

, and pes. The bones are similar to '' Zuolong'', a similar dinosaur from the late Jurassic of China. Based on osteohistological studies, the specimen of ''Aratasaurus'' is a juvenile/young adult, about four years old at the time of death. It has been estimated to be around long and weigh around

Classification

''Aratasaurus'' was placed in the

Coelurosauria Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, ty ...

in a basal position, as the sister taxon of '' Zuolong''.

Paleoecology

Other non-avian dinosaurs from the early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

include '' Irritator challengeri'', ''Santanaraptor placidus'', and ''Mirischia assymetrica''.

References

{{Taxonbar, from=Q97149323 Prehistoric coelurosaurs Albian life Early Cretaceous dinosaurs of South America Cretaceous Brazil Fossils of Brazil Romualdo Formation Fossil taxa described in 2020