Eoraptor, scientifically known as Eoraptor lunensis, holds a significant place in the dinosaur family tree as one of the earliest-known members. It may have been the most primitive dinosaur yet to be discovered. This dinosaur lived approximately 230 million years ago in what is now Argentina. Its name translates to "dawn thief," signifying its status as one of the earliest dinosaurs discovered. The first Eoraptor fossils were discovered in 1991 in the Ischigualasto Formation, providing paleontologists with evidence about the early stages of dinosaur evolution.

Eoraptor possessed a unique blend of characteristics that both resembled and differed from later dinosaur species. It was a small dinosaur, measuring around 1 to 1.5 meters in length and weighing around 10 to 15 kilograms. Its skeletal structure exhibited features common to both theropod and sauropodomorph dinosaurs, indicating its transitional nature. Eoraptor had long hind limbs and sharp, serrated teeth, suggesting a carnivorous diet, although it may have also consumed plant material. It had five fingered hands, although the fith finger was very small.

Eoraptor inhabited a landscape that was part of the ancient supercontinent Pangaea, characterized by arid and semi-arid environments. Its discovery is of immense significance as it provides a window into the early stages of dinosaur evolution, serving as an important bridge between early archosaur ancestors and later dinosaur lineages. Eoraptor showcases key features and characteristics that would evolve and diversify in later dinosaur species, contributing to our understanding of their evolutionary adaptations and ecological success.