Ichthyosaur

Ichthyosaurs were a group of extinct marine reptiles that inhabited oceans from the Early Triassic to the Late Cretaceous, roughly 250 to 90 million years ago. Despite the name, they were not fish but reptiles that evolved a highly aquatic lifestyle. The term ichthyosaur comes from Greek for "fish lizard," reflecting their fish-like shape.

Physically, ichthyosaurs possessed a streamlined body with a long, narrow snout and, in many species, paddle-like limbs that functioned as flippers. They had a relatively large eye in some lineages, suggesting good vision, and a powerful tail that helped propel them through water. Their bodies varied from small to very large, with some individuals exceeding several meters in length. The skeletons indicate adaptations for fast, efficient swimming.

Ichthyosaurs were carnivores, feeding primarily on fish and cephalopods. Teeth ranged from conical and sharp to more robust in different species, reflecting diverse feeding strategies. Most ichthyosaurs appear to have given birth to live young in the sea (viviparous), a reproductive strategy well suited to an oceanic lifestyle.

Distribution and significance: ichthyosaurs have fossils found worldwide, with abundant remains in Europe, North America, and elsewhere. They first appeared after the Permian mass extinction and became highly successful during the Triassic and Jurassic periods, before their decline and extinction in the Late Cretaceous. They are an important example of convergent evolution toward a fish-like body form among terrestrial reptiles and provide key insights into marine reptile adaptation and reproductive biology. Notable genera include Ichthyosaurus, Temnodontosaurus, Stenopterygius, and Ophthalmosaurus.