The Online Library of Knowledge

Marine reptiles


Ichthyosaurus chasing after ammonitesIchthyosaurus chasing after ammonites Ichthyosaurus was a marine reptile that lived during the Early Jurassic Period. The name Ichthyosaurus means “fish lizard”, with its close relatives forming the ichthyosaur family. Its body was similar in shape to that of a dolphin. It had a slim, pointed snout, fish-like tail, two sets of flippers and a dorsal fin. The front flippers were twice the size of the back ones, with five “fingers” inside each of them. Its nostrils were set far back on its snout near its eyes. Its teeth were conical in shape. Ichthyosaurus’s main method of finding prey would have been by using its exceptional vision.


A perfectly preserved fossil of IchthyosaurusA perfectly preserved fossil of IchthyosaurusSeveral hundred complete fossils of Ichthyosaurus have been found, many in perfect condition. They show the structure of the fingers and toes inside its flippers. Some are of pregnant mothers, revealing even the bones of their babies inside. A few were fossilized during the birth process itself. The fossils show that they normally only had two babies, although some had as many as 11. Ichthyosaurus's young were born live and emerged from the mother’s body tail first, just as whale calves do today. They could swim immediately after birth.

The ichthyosaurs probably died out because of competition from other marine reptiles and because, by the Mid-Cretaceous, their rivals, the sharks, had evolved into the powerful predators they are today.

© 2020 Q-files Ltd. All rights reserved. Switch to Mobile