ik·thee·uh·saw·ruhsik·thee·uh·saw·ruhsIchthyosaurs were reptiles that were strong swimmers fully adapted to life in the seas. They were better adapted than any other reptiles, although they still needed to go to the surface periodically to breathe air. Ichthyosaurs were stream-lined marine reptiles that ranged in size from 7-30 feet long (4.5-9 m). They had sharp teeth in long jaws, and big eyes. They had four crescent-shaped fins, a stabilizing dorsal fin, and a fish-like tail with two lobes. They breathed air with lungs through nostrils which were close to the eyes near the top of the snout. They gave birth to live young; fossils have been found with baby Ichthyosaurs in the abdomen. Ichthyosaurs lived during the Mesozoic era. They appeared during the Triassic, reached their peak during the Jurassic, and disappeared during the Cretaceous, about 95 million years ago. Ichthyosaurs lived in the oceans, probably near the surface (they had large eyes, which would be unnecessary is they spent a lot of time diving into the dark depths of the oceans. They did not move about on land. Ichthyosaurs were viviparous; they gave birth in the water to live young (instead of laying eggs, as other reptiles do). This is known because the fossilized bones of baby Ichthyosaurs have been found inside the stomach of the female adults. Ichthyosaurs were carnivores; they ate fish, octopus, and other swimming animals. They had strong jaws and sharp teeth. Ichthyosaurs were fast and strong swimmers; they stabilized themselves in the water with their four, strong, crescent-shaped fins. Primitive Ichthyosaurs swam in a fish-like fashion, moving the tail from side to side to propel themselves through the water. Ichthyosaurs could not move about on land.