The Iguanodon, a large herbivorous dinosaur, offers a glimpse into Earth’s ancient past. Understanding when this creature roamed helps contextualize geological time and the dynamic history of life. It provides valuable insights into the prehistoric world, particularly the Mesozoic Era.
The Iguanodon’s Primary Era
The Iguanodon lived during the Early Cretaceous period, approximately 126 to 122 million years ago. While some species within the broader iguanodontian group might have appeared in the Late Jurassic, the Iguanodon genus, particularly Iguanodon bernissartensis, became prominent in the Early Cretaceous. The Cretaceous period, the final segment of the Mesozoic Era, often called the “Age of Dinosaurs,” spanned nearly 80 million years, from about 145 to 66 million years ago, ending with a major extinction event.
A Snapshot of the Cretaceous World
During the Early Cretaceous, Earth’s climate was warm, with little to no polar ice caps. The supercontinent Pangaea continued to break apart, leading to changes in global geography and ocean circulation. Dominant plant life included conifers, cycads, and ferns, which formed vast forests. This era also marked the emergence and initial diversification of flowering plants, or angiosperms, around 130 to 125 million years ago, fundamentally changing ecosystems.
Iguanodon shared its habitat with diverse life forms. Large carnivorous dinosaurs, such as Baryonyx and Megalosaurus, were potential predators. Other herbivores, including various iguanodontians and early ceratopsids, also roamed these landscapes. Early mammals were present, though generally small, and primitive birds took to the skies, some resembling small dinosaurs while others began to evolve features akin to modern birds. The environment featured evolving flora and fauna, with Iguanodon as a large herbivore.
Iguanodon’s Enduring Legacy
Iguanodon is notable in paleontological history as one of the first dinosaurs formally named and described. Its discovery in the early 19th century, based on teeth found in England by Gideon Mantell, provided some of the earliest clues about these ancient reptiles. Its name, “Iguanodon,” meaning “iguana-tooth,” reflects its dental similarities to modern iguanas.
Fossils of Iguanodon, particularly the numerous complete skeletons found in Belgium, have revealed much about its lifestyle. These discoveries showed its large thumb spikes, which were initially misinterpreted but later understood to be located on its hands. The function of these spikes is debated, with possibilities including defense against predators, combat among individuals, or stripping foliage from branches for food. Its unique teeth, adapted for grinding tough plant material, and its ability to move on both two and four legs, show it was a versatile herbivore well-suited to the Early Cretaceous world.