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Eoraptor was one of the world's earliest dinosaur
Dinosaur

Dinosaurs were the dominant vertebrate animals of Landform ecosystems for over 160 million years, from the late Triassic Period until the end of the Cretaceous Period , when most of them became extinct in the Cretaceous?Tertiary extinction event....
s. It was a two-legged
Biped

Bipedalism is a form of terrestrial locomotion where an organism Motion 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" ....
 meat-eater
Carnivore

A carnivore , meaning 'meat eater' , is any animal with a diet consisting mainly of meat, whether it comes from animals living or dead .In a more general sense, an animal may be considered a carnivore if it prefers feeding on animal matter over plant matter....
 that lived between 230 and 225 million years ago, in what is now the northwestern region of Argentina
Argentina

Argentina, officially the Argentine Republic , is a country in South America, constituted as a federation of 23 provinces and an autonomous city....
. The type species
Type species

In taxonomy, a type species is the species that originally defined a genus . It is an individual specimen that fixes the name of a genus . Two different definitions are used interchangeably, in a general term and a botanical term....
 is Eoraptor lunensis, which means 'dawn plunderer [from the Valley] of the Moon', denoting where it was originally discovered (Greek
Ancient Greek

Ancient Greek is the historical stage in the development of the Greek language spanning across the Archaic Greece , Classical Greece , and Hellenistic civilization periods of ancient Greece and the classical antiquity....
 eos/e?? meaning 'dawn' or 'morning' and Latin
Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
 lunensis meaning 'of the moon').






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Eoraptor was one of the world's earliest dinosaur
Dinosaur

Dinosaurs were the dominant vertebrate animals of Landform ecosystems for over 160 million years, from the late Triassic Period until the end of the Cretaceous Period , when most of them became extinct in the Cretaceous?Tertiary extinction event....
s. It was a two-legged
Biped

Bipedalism is a form of terrestrial locomotion where an organism Motion 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" ....
 meat-eater
Carnivore

A carnivore , meaning 'meat eater' , is any animal with a diet consisting mainly of meat, whether it comes from animals living or dead .In a more general sense, an animal may be considered a carnivore if it prefers feeding on animal matter over plant matter....
 that lived between 230 and 225 million years ago, in what is now the northwestern region of Argentina
Argentina

Argentina, officially the Argentine Republic , is a country in South America, constituted as a federation of 23 provinces and an autonomous city....
. The type species
Type species

In taxonomy, a type species is the species that originally defined a genus . It is an individual specimen that fixes the name of a genus . Two different definitions are used interchangeably, in a general term and a botanical term....
 is Eoraptor lunensis, which means 'dawn plunderer [from the Valley] of the Moon', denoting where it was originally discovered (Greek
Ancient Greek

Ancient Greek is the historical stage in the development of the Greek language spanning across the Archaic Greece , Classical Greece , and Hellenistic civilization periods of ancient Greece and the classical antiquity....
 eos/e?? meaning 'dawn' or 'morning' and Latin
Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
 lunensis meaning 'of the moon'). Paleontologists believe the Eoraptor resembles the common ancestor of all dinosaur
Dinosaur

Dinosaurs were the dominant vertebrate animals of Landform ecosystems for over 160 million years, from the late Triassic Period until the end of the Cretaceous Period , when most of them became extinct in the Cretaceous?Tertiary extinction event....
s. It is known from several well-preserved skeletons.

Description and behavior

It had a thin body that grew to about 1 meter (3 ft) in length, with an estimated weight of about 10 kilogram
Kilogram

The kilogram or kilogrammeThe spelling kilogram is used by the International Committee for Weights and Measures and the U.S....
s (22 lb
Pound (mass)

The pound or pound-mass is a Units of measurement of massused in the Imperial unit, United States customary units and other systems of measurement....
). It ran digitigrade
Digitigrade

A digitigrade is an animal that stands or walks on its digits, or toes. Digitigrades include walking birds , cats, dogs, and most other mammals, but not humans, bears, and a few others ....
, upright on its hind legs. Its fore limbs were only half the length of its hind limbs and it had five digits on each 'hand'. Three of those digits, the longest of the five, ended in large claw
Claw

A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end of the leg or Arthropod leg for gripping a surface as the creature walks....
s and were presumably used to handle prey. Scientists have surmised that the fourth and fifth digits were too tiny to be of any use in hunting.

Eoraptor probably ate mostly small animal
Animal

Animals are a major group of multicellular, eukaryotic organisms of the Kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life....
s. It was a swift sprinter and, upon catching its prey, it would use claws and teeth to tear the prey apart. However, it had both carnivore-type
Carnivore

A carnivore , meaning 'meat eater' , is any animal with a diet consisting mainly of meat, whether it comes from animals living or dead .In a more general sense, an animal may be considered a carnivore if it prefers feeding on animal matter over plant matter....
 and herbivore-type
Herbivore

Herbivory is a form of predation in which an organism, known as an herbivore, heterotrophs principally autotrophs such as plants, algae and photosynthesizing bacteria....
 teeth, so it could possibly have been omnivorous
Omnivore

Omnivores are species that eating both plants and animals as their primary food source. They are opportunistic, general feeders not specifically adapted to eat and digest either meat or plant material exclusively....
.

Early dinosaur

The bones of this primitive dinosaur were first discovered in 1991, by University of San Juan paleontologist Ricardo Martínez, during field work conducted by the University of Chicago
University of Chicago

The University of Chicago is a private university located principally in the Hyde Park, Chicago neighborhood of Chicago. Although an older university by the same name existed prior to its founding, the modern University of Chicago credits its founding to the oil magnate John D....
 and the University of San Juan in the Ischigualasto Basin of Argentina
Argentina

Argentina, officially the Argentine Republic , is a country in South America, constituted as a federation of 23 provinces and an autonomous city....
. During the Late Triassic
Triassic

The Triassic is a geologic period that extends from about 251 to 199 annum . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic....
 Period, this was a river valley but is now desert
Désert

?D?sert? is ?milie Simon's debut single, released in October 2002. The song was a huge success both critically and commercially in her homeland....
 badlands
Badlands

A badlands is a type of arid terrain where softer sedimentary rocks and clay-rich soils have been extensively Erosion by wind and water. It can resemble malpa?s, a terrain of volcanic rocks....
. Eoraptor was found in the Ischigualasto Formation, the same formation that yielded Herrerasaurus
Herrerasaurus

Herrerasaurus was one of the earliest dinosaurs. All known specimens of this carnivore have been discovered in northwest of Argentina, in late Triassic Period rocks ....
, a very early theropod. By 1993 paleontologist Paul Sereno
Paul Sereno

Paul Callistus Sereno is an United States paleontology who is the discoverer of several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco and Niger....
 determined it to be one of the earliest dinosaur
Dinosaur

Dinosaurs were the dominant vertebrate animals of Landform ecosystems for over 160 million years, from the late Triassic Period until the end of the Cretaceous Period , when most of them became extinct in the Cretaceous?Tertiary extinction event....
s. Its age was determined by several factors, not least because it lacked the specialised features of any of the major groups of later dinosaurs, including its lack of specialized predatory features. Unlike later carnivores, it lacked a sliding joint at the articulation of the lower jaw
Jaw

The jaw is either of the two opposable structures forming, or near the entrance to the mouth.The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of most animals....
, with which to hold large prey. Furthermore, only some of its teeth were curved and saw-edged, unlike those in a later predator's mouth.

Eoraptor belonged to a major group of dinosaurs called saurischia
Saurischia

Saurischia is one of the two Order s, or basic divisions, of dinosaurs. In 1888, Harry Seeley classified dinosaurs into two orders, based on their hip structure....
ns, or lizard-hipped dinosaurs. Their hip structures are similar to that of the modern lizard.

The fact that it possessed some herbivore
Herbivore

Herbivory is a form of predation in which an organism, known as an herbivore, heterotrophs principally autotrophs such as plants, algae and photosynthesizing bacteria....
 teeth and five fully developed 'fingers' has led scientists to place Eoraptor at more ancient than even Herrerasaurus. Only some prosauropods, recently discovered in Madagascar
Madagascar

Madagascar, or Republic of Madagascar , is an island nation in the Indian Ocean off the southeastern coast of Africa. The main island, also called Madagascar, is the List of islands by area, and is home to 5% of the world's plant and animal species, of which more than 80% are Endemism to Madagascar....
, are thought to be older. There is a possibility that Staurikosaurus
Staurikosaurus

Staurikosaurus is a genus of early dinosaur from the Late Triassic of Brazil....
 may be older, but it is rather large. Staurikosaurus seems to have features in common with both prosauropods and theropods, which has led scientists to question how primitive Eoraptor was in relation to other dinosaurs.

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