Iguanodonts

Iguanodonts are a group of herbivorous dinosaurs within the clade Ornithopoda, which thrived during the Late Jurassic to the Late Cretaceous periods, approximately 161 to 100 million years ago. They are known for their robust bodies, grinding teeth, and distinctive thumb spikes, which likely served for defense or foraging.

The first iguanodonts were discovered in the 19th century and include the genus Iguanodon, one of the earliest dinosaurs described scientifically. Iguanodons were large, with some species reaching lengths of up to 10 meters (33 feet). They had a bulky body, a long tail for balance, and limbs adapted for both walking and running. Their skulls featured beak-like mouths suitable for cropping plants, and their teeth were arranged to process fibrous vegetation efficiently.

Iguanodonts exhibit a variety of skeletal adaptations. Many possessed powerful hind limbs, enabling them to move bipedally or quadrupedally, depending on activity. The hand displayed a prominent, conical thumb spike, which may have been used for defense or in social interactions. Their pelvis and limb structure suggest they could switch between walking on two legs and using all fours.

Fossil finds of iguanodonts have been uncovered in Europe, North America, Africa, and Asia, indicating they had a wide geographic distribution. They are considered key herbivores in their ecosystems, contributing to the understanding of dinosaur diversity during the Cretaceous period.

Iguanodonts are important in paleontology as they mark a transition between more primitive ornithopods and more advanced hadrosaurs (duck-billed dinosaurs). Their adaptations highlight evolutionary trends toward more complex herbivorous dentitions and locomotive versatility.