Unaysaurus
Encyclopedia
Unaysaurus is a genus
of sauropodomorph
dinosaur
, and is one of the oldest dinosaurs known. It was discovered in southern Brazil
,in the geopark
of paleorrota
, in 1998, and announced in a press conference on Thursday, December 3, 2004. A member of a group of plant-eating
dinosaur
s known as "prosauropods", it is closely related to a dinosaur found in Germany
, which indicates that it was relatively easy for species
to spread across the giant landmass of the time, the supercontinent
of Pangaea
.
Like most early dinosaurs, Unaysaurus was relatively small, and walked on two legs
. It was only 2.5 meters long (8.2 ft), 70 to 80 centimeters tall (2 to 3 ft), and weighed about 70 kilogram
s (155 lb
).
The fossil
s of Unaysaurus are well preserved. They consist of an almost complete skull
, complete with a lower jaw
, and partial skeleton with many of the bones still connected to each other in their natural positions. It is one of the most complete dinosaur skeletons, and the most complete skull, ever recovered in Brazil.
s of the late Triassic
period. It was found in the south of Brazil, which at the time was connected to northwest Africa
. The whole world was united into the great supercontinent of Pangaea, which was just starting to divide into Laurasia
in the north, and Gondwana
in the south.
Unaysaurus was found in the southern Brazilian state of Rio Grande do Sul
, near the city of Santa Maria
. It was recovered from the red beds of the Caturrita Formation
, which is the geologic formation where similarly old dinosaurs like Saturnalia
have been found. The oldest dinosaurs in the world are from here and nearby in Argentina
(like the Eoraptor
), which suggests that the first dinosaurs may have originated in the area.
Unaysaurus is the first prosauropod discovered in Brazil. Prosauropods were semi-bipedal, herbivorous
dinosaurs that are related to the later and more advanced sauropods, which include some of the largest creatures ever to walk the Earth, like the Brachiosaurus
. Staurikosaurus
, another early dinosaur, has been discovered nearby, and it is possible that Teyuwasu
, another Brazilian dinosaur described in 1999, is also a prosauropod.
Counter to expectations, however, the closest relative of Unaysaurus is not from South America
. It is mostly closely related to the Plateosaurus
, which lived about 210 million years ago in Germany
. This indicates that species were able to migrate relatively easily across Pangaea.
language, which in turn refers to Agua Negra (also "black water"), the Portuguese
name for the region where the fossils were found. The species epithet tolentinoi is named after Tolentino Marafiga, who discovered the fossils by the side of a road in 1998.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sauropodomorph
Sauropodomorpha
Sauropodomorpha is an extinct clade of long-necked, herbivorous, saurischian dinosaurs which includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
, and is one of the oldest dinosaurs known. It was discovered in southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
,in the geopark
Geopark
A Geopark is defined by the United Nations Educational, Scientific and Cultural Organization in its UNESCO Geoparks International Network of Geoparks programme as follows:...
of paleorrota
Paleorrota
Paleorrota , is a geopark located in the center of the Brazilian state of Rio Grande do Sul. The rocks and fossils found along the route date back to the times when there was only one supercontinent Pangaea....
, in 1998, and announced in a press conference on Thursday, December 3, 2004. A member of a group of plant-eating
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s known as "prosauropods", it is closely related to a dinosaur found in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, which indicates that it was relatively easy for species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
to spread across the giant landmass of the time, the supercontinent
Supercontinent
In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...
of Pangaea
Pangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
.
Like most early dinosaurs, Unaysaurus was relatively small, and walked on two legs
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
. It was only 2.5 meters long (8.2 ft), 70 to 80 centimeters tall (2 to 3 ft), and weighed about 70 kilogram
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
s (155 lb
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...
).
The fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of Unaysaurus are well preserved. They consist of an almost complete skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, complete with a lower jaw
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
, and partial skeleton with many of the bones still connected to each other in their natural positions. It is one of the most complete dinosaur skeletons, and the most complete skull, ever recovered in Brazil.
One big world
Unaysaurus lived about 200 to 225 million years ago, in the Carnian to Norian ageFaunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
s of the late Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
period. It was found in the south of Brazil, which at the time was connected to northwest Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. The whole world was united into the great supercontinent of Pangaea, which was just starting to divide into Laurasia
Laurasia
In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately...
in the north, and Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
in the south.
Unaysaurus was found in the southern Brazilian state of Rio Grande do Sul
Rio Grande do Sul
Rio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
, near the city of Santa Maria
Santa Maria, Rio Grande do Sul
Santa Maria is a municipality in the central region of Rio Grande do Sul, the southernmost state of Brazil. In 2007, its population was 263,403 inhabitants in a total area of 1,823 km2.-Importance:...
. It was recovered from the red beds of the Caturrita Formation
Caturrita Formation
The Caturrita Formation is a rock formation found in Rio Grande do Sul, Brazil. Its sediments were deposited in the Paraná Basin. The formation has a late Carnian to early Norian age and forms part of the Santa Maria Supersequence in the upper section of the Rosário do Sul Group.-Etymology:The...
, which is the geologic formation where similarly old dinosaurs like Saturnalia
Saturnalia (dinosaur)
Saturnalia is an extinct genus of basal sauropodomorph dinosaur known from the Triassic of Rio Grande do Sul, southern Brazil.-Discovery:Saturnalia was originally named on the basis of three partial skeletons...
have been found. The oldest dinosaurs in the world are from here and nearby in Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
(like the Eoraptor
Eoraptor
Eoraptor was one of the world's earliest dinosaurs. It was a two-legged saurischian, close to the ancestry of theropods and sauropodomorphs. It lived ca. 231.4 million years ago, in what is now the northwestern region of Argentina...
), which suggests that the first dinosaurs may have originated in the area.
Unaysaurus is the first prosauropod discovered in Brazil. Prosauropods were semi-bipedal, herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
dinosaurs that are related to the later and more advanced sauropods, which include some of the largest creatures ever to walk the Earth, like the Brachiosaurus
Brachiosaurus
Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...
. Staurikosaurus
Staurikosaurus
Staurikosaurus is a genus of herrerasaurid dinosaur from the Late Triassic of Brazil.-Discovery:The first known specimen of Staurikosaurus was recovered from the Paleontological Site Jazigo Cinco of the Santa Maria Formation in the geopark of paleorrota , Rio Grande do Sul, southern Brazil...
, another early dinosaur, has been discovered nearby, and it is possible that Teyuwasu
Teyuwasu
Teyuwasu is a dubious genus of dinosaur from the Late Triassic. Named by Edio-Ernst Kischlat in 1999, little is currently known about this genus; the type species, T. barbarenai, was named from leg bones discovered in geopark of paleorrota, Brazil. The specific name honors Dr. Mário Costa...
, another Brazilian dinosaur described in 1999, is also a prosauropod.
Counter to expectations, however, the closest relative of Unaysaurus is not from South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. It is mostly closely related to the Plateosaurus
Plateosaurus
Plateosaurus is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 216 to 199 million years ago, in what is now Central and Northern Europe. Plateosaurus is a basal sauropodomorph dinosaur, a so-called "prosauropod"...
, which lived about 210 million years ago in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. This indicates that species were able to migrate relatively easily across Pangaea.
Discovery and name
The new species and genus were officially described by Luciano A. Leal, Sergio A. K. Azevodo, Alexander W. A. Kellner, and Átila A. S. da Rosa in the October 18, 2004 issue of the scientific journal Zootaxa. The name Unaysaurus comes from the word unay (u-na-hee), meaning "black water" in the local TupiTupian languages
The Tupi or Tupian language family comprises some 70 languages spoken in South America, of which the best known are Tupi proper and Guarani.-History, members and classification:...
language, which in turn refers to Agua Negra (also "black water"), the Portuguese
Portuguese language
Portuguese is a Romance language that arose in the medieval Kingdom of Galicia, nowadays Galicia and Northern Portugal. The southern part of the Kingdom of Galicia became independent as the County of Portugal in 1095...
name for the region where the fossils were found. The species epithet tolentinoi is named after Tolentino Marafiga, who discovered the fossils by the side of a road in 1998.