Coelophysis was an early dinosaur. This small, agile creature was a slender, bipedal carnivore, reaching about 3 meters (9.8 feet) in length and weighing around 25 kilograms (55 pounds). Its name, meaning “hollow form,” refers to its lightweight, hollow bones, which contributed to its speed and agility. Coelophysis was one of the earliest known theropods, a group of two-legged, carnivorous dinosaurs that would later include much larger predators.
Its Ancient Timeline
Coelophysis inhabited Earth during the Late Triassic period, spanning 237 to 201.4 million years ago. The Triassic period itself, lasting from about 251.9 to 201.4 million years ago, marked the beginning of the Mesozoic Era. It was a time of recovery and diversification following Earth’s most severe mass extinction event.
The Late Triassic is often recognized as the “dawn of dinosaurs,” as many of the earliest dinosaur groups, including Coelophysis, made their appearance. These pioneering dinosaurs set the evolutionary groundwork for the more diverse and larger forms that would dominate later eras. Coelophysis is specifically dated to have lived from around 215 to 201.4 million years ago.
Unearthing the Past
Scientists determined the age of Coelophysis through fossil discoveries and geological dating methods. The first remains were found in New Mexico in 1881 by David Baldwin, described by Edward Drinker Cope in 1889. In 1947, paleontologists Edwin Colbert and George Whitaker uncovered hundreds of Coelophysis skeletons at Ghost Ranch, New Mexico.
This site, part of the Chinle Formation, provided well-preserved fossils, offering insights into the species. The number of individuals found together suggests a catastrophic event, such as a flash flood, rapidly buried the animals. To establish the age of these fossils, scientists use radiometric dating, which measures the decay of radioactive isotopes in volcanic ash layers found above and below the fossil-bearing rocks. This method, along with stratigraphy (studying rock layers), helps place the fossils within the geological timescale.
An Early Dinosaur’s World
During the Late Triassic period, when Coelophysis roamed, Earth’s landmasses merged into a single supercontinent called Pangea. This continent stretched across the globe, influencing the planet’s climate and environments. The interior of Pangea experienced hot and arid conditions, characterized by deserts.
Despite the dry climate, some regions, particularly coastal areas and river floodplains, supported more humid and tropical conditions. There were no polar ice caps, contributing to a warmer global climate. Coelophysis shared its world with other creatures, including crocodilian-like phytosaurs, herbivorous aetosaurs, and predatory rauisuchians. Plant life consisted mainly of conifers, ferns, cycads, and ginkgos.