Megalosaurus, meaning “great lizard,” holds a unique position in paleontology. It was the first non-avian dinosaur formally identified and scientifically named. Its recognition marked a pivotal moment, shifting human understanding of Earth’s deep past and setting the stage for prehistoric life exploration.
Megalosaurus’s Jurassic Home
Megalosaurus roamed Earth during the Middle Jurassic Period, specifically the Bathonian stage, approximately 168 to 164 million years ago. This was an era when dinosaurs were establishing their dominance. Primary fossil evidence comes from southern England, particularly Oxfordshire, Gloucestershire, and Warwickshire. While some fragments from France and Portugal are tentatively associated, the most definitive remains are from England. This large carnivorous theropod was a significant predator in its European habitat during this Jurassic window.
The World of the Mid-Jurassic
The Middle Jurassic Period had a generally warm and humid climate. Global temperatures were elevated, and evidence suggests a less severe temperature difference between the equator and the poles compared to present conditions. This enabled lush, widespread vegetation. Plant life was dominated by gymnosperms, including vast conifer forests, alongside abundant cycads, ginkgoes, and various ferns.
During this time, the supercontinent Pangaea was continuing its process of breaking apart, influencing geographical distributions and creating new coastal environments where Megalosaurus likely thrived. Alongside Megalosaurus, the Middle Jurassic ecosystems were home to a variety of other dinosaurs, such as large herbivorous sauropods like Cetiosaurus and armored stegosaurs. Small, shrew-sized early mammals also scurried beneath the towering vegetation. The skies were navigated by pterosaurs, while marine environments teemed with creatures like ichthyosaurs, plesiosaurs, and formidable pliosaurs.
Unearthing the First Dinosaur
Understanding Megalosaurus began before the concept of “dinosaur” existed. The earliest recorded fossil discovery was a femur fragment in Oxfordshire, England, in 1676. Naturalist Robert Plot described and illustrated this bone, though he misinterpreted it as belonging to a giant human or Roman war elephant.
Centuries later, William Buckland, a geology professor at Oxford, studied these and other fossil finds. On February 20, 1824, Buckland formally announced and described Megalosaurus to the Geological Society of London, giving it its enduring scientific name. This predated Richard Owen’s 1842 coining of “Dinosauria,” which unified ancient reptiles under a single classification. The discovery challenged prevailing views of Earth’s age and the history of life, initiating a scientific pursuit of the planet’s prehistoric past.