The Ichthyosaurus, meaning "fish lizard," belongs to the order Ichthyosauria and thrived during the Triassic, Jurassic, and Cretaceous periods. It represents a diverse group of marine reptiles that inhabited oceans worldwide. The first Ichthyosaurus fossil was discovered in the early 19th century in England.

The Ichthyosaurus had a streamlined body, resembling a dolphin, which allowed it to glide efficiently through the water. It ranged in size, with some species measuring around 1.5 to 4 meters in length. Ichthyosaurus had a long snout filled with sharp teeth that facilitated catching and consuming fish and other marine prey. Their limbs evolved into paddle-like structures, which aided in propulsion and steering underwater.

Ichthyosaurs possessed well-developed eyes and likely had excellent vision, allowing them to navigate and locate prey in dimly lit underwater environments. Fossil evidence suggests they may have given birth to live young, indicating viviparity as an adaptation to their marine existence.