Eoraptor was a Very Primitive Dinosaur
Eoraptor, pronounced “EE-oh-RAP-tor, was one of the earliest known dinosaurs. It’s name comes from the Greek, meaning “Dawn plunderer”. It lived in the Triassic period, about 228 million years ago. Eoraptor lived in what is today the northwestern region of South America. Eoraptor was from the saurischia, or “lizard-hipped”, order of dinosaurs and is considered to be a very primitive theropod-like species. It also belongs to the infraorder Herrerasauria which includes other early dinosaurs, like Herrerasaurus and Saltopus.
Quick Facts
| Name | Eoraptor |
| Prehistoric Era | Middle Triassic |
| Classification | Omnivore |
| Order | Saurischia |
| Suborder | Theropoda |
| Weight | 10 – 20 lbs (4.5 – 9 kg) |
| Length | 3 feet (1 meters) |
| Height | 1 feet (30 centimeters) |
| Maximum Speed | Approximately 25 MPH |
| Territory | South America |
What did Eoraptor Look Like?
You could say that Eoraptor looked like a somewhat miniature model of larger raptor dinosaur species. There were no particular features that indicated a unique specialty and it was small, only about the size of a small to medium-sized dog, and about 3 feet long. But it was bipedal, so it stood on its back legs. Eoraptor’s body was lightly-built with long, thin legs and a long tail. Its arms had 5 fingers which may possibly have been used for scavenging. Two of the fingers were quite small. The remaining three fingers had sharp claws and could have been used to hold prey. Eoraptor’s feet had three toes, also with sharp claws.
Physical Attributes of Eoraptor
Paleontologists look at Eoraptor’s generic appearance as being characteristic of the earliest known dinosaurs, whose evolutionary descendants would gradually develop more specialized features according to the environment they lived in. Perhaps the most unique feature, for a dinosaur, that could be attributed to Eoraptor would be its light, hollow bones, especially considering that its eventual descendants would be relatives of some of the biggest creatures known to walk the earth. With that said however, even the large theropods like Tyrannosaurus Rex had honeycombing within the bones to create a much lighter skeleton. If two words had to be used to describe Eoraptor, they would be “long” and “light”. It had long legs, a long tail, and a long head with many small, sharp teeth; however, it only weighed about 20 pounds.
What did Eoraptor Eat?
Like most theropods, Eoraptor ate meat. But paleontologists suspect that it ate plants too because it had teeth normally associated with herbivores, as well as teeth normally associated with carnivores. So paleontologists tend to conclude it was an omnivore. Paleontologists also suspect that it may have been a scavenger, which seems likely considering it was so small.
Where did Eoraptor Live?
Eoraptor lived in what is now modern day South America during the Triassic period. The first fossil of this small theropod-like dinosaur was found in the Ischigualasto Basin which is located in Argentina. The basin was formed from a river that was actually there during the time that Eoraptor would have lived. Now the area is a desert and not very supportive of wildlife, but the environment would have been milder and greener during the Triassic.
How did Eoraptor Move?
Eoraptor was bipedal and digitigrade, so it moved upright on the ground using its two back legs. Its legs were small, but long, and its long tail was useful for maintaining balance. Therefore, it would have been a pretty fast runner for his size.
Discovery of Eoraptor
Eoraptor was first discovered by Ricardo Martinez in 1991 in the Ischigualasto Basin of Argentina, South America. He worked at the University of San Juan and was doing field work for them and the University of Chicago in the area. Another primitive theropod, Herrerasaurus, was found in the same rock formation as Eoraptor. A total of three Eoraptor skeletons have been found to date, all of which were found in the Basin. In 1993, the news of an almost whole, one-meter-long skeleton of the primitive bipedal theropod-like raptor was published by paleontologist Paul Sereno and his team. They determined it was a very early dinosaur because of its lack of specialized features, such as a sliding joint in the jaw that later predatory dinosaurs developed to hold larger prey items. Later carnivorous dinosaurs also had exclusively curved and saw-edged teeth, but Eoraptor only had some of those teeth. The type species name that they gave it, “Eoraptor lunensis”, means “dawn plunderer from the Valley of the Moon”. Valley of the moon is the English translation of the region’s Spanish nickname “Valle de la luna”. The name refers to the otherworldly appearance of the dry badlands around the Ischigualasto formation.
The Importance of Eoraptor
In an odd way, Eoraptor’s generic appearance is what makes it significant. That is how paleontologists knew what time period to place the dinosaur. They believe Eoraptor, and primitive dinosaurs like it, served as sort of a template for later dinosaurs. There is some debate that it might not have been technically a dinosaur, but a closely related archosaur. Other paleontologists point out that its functional three-fingered hand indicates a connection to theropod dinosaurs. Regardless of Eoraptor’s strict classification, it still provides a good example of where and when dinosaurs began, and what they looked like in the dawn of their creation.
