Ichthyosaurs are an extinct group of marine reptiles belonging to the order ichthyopterygia. They first appeared during the Early Triassic period, about 245 million years ago, and became extinct during the Late Cretaceous period, about 90 million years ago. The name “ichthyosaur” comes from the Greek word for “fish lizard”.
Ichthyosaurs were among the largest predators of their time. Their size ranged from 1 meter (3 feet) to 20 meters (66 feet) in length, and they weighed up to 50 metric tons (55 short tons). They had a long body with a dolphin-like tail fin, and two pairs of paddle-like limbs that were used for propulsion through the water. Ichthyosaurs were air-breathing reptiles that gave birth to live young; however, unlike other reptiles, they did not lay eggs.
The first ichthyosaur fossil was discovered in 1784 by Mary Anning, a British fossil collector. Since then, over 200 species of ichthyosaurs have been identified worldwide. Ichthyosaurs were once thought to be closely related to mosasaurs (another group of extinct marine reptiles), but recent evidence suggests that they are more closely related to dinosaurs than to mosasaurs.
Ichthyosaurswere successful marine predators for millions of years; however, they went extinct during the Late Cretaceous period along with many other groups of organisms (including dinosaurs). The exact cause(s) of their extinction is still unknown; however, several theories have been proposed, including climate change and competition from other marine predators such as plesiosaurs and sharks.