|Ichthyosaurs Rib Bone, from Lyme Regis, Dorset, England
195 Million Years Old, Lower Jurassic Period
Height - 2.6 cm
Width - 2.5 cm
Length - 7 cm
Ichthyosaurs (Greek for "fish lizard" - or ichthys meaning "fish" and sauros meaning "lizard") are large marine reptiles. Various books and resources will vary on the size of which an Ichthyosaur could grow but from 1m (3ft) of the smaller species to 20m (65ft) of the largest Ichthyosaurs of the Triassic and early Jurassic is a common theory.
Ichthyosaurs looked cross between a dolphin and a shark. This is whats called ‘convergent evolution’, when different organisms come to resemble each other due to similar habitat and/or lifestyle. The Jaw of Ichthyosaur were very long, slim and pointed - similar to a dolphin’s beak, only more exaggerated. A predatory species Ichthyosaurs had many small, sharp teeth and fed on fish and squid.
Studies of the fossil suggests that the eye of many types Ichthyosaurs were large, an indication that they may of or did hunt at night or the deep where light was poor. All four limbs were modified as paddles, with the front pair usually larger than the rear ones.
These were used mainly for steering, manoeuvring and braking. A dolphin like fin on the back prevented the animal leaning or rolling to the side. The tail bones angled down at the end to support a large upright fin, similar to the tail of a fish. Swishing this from side to side provided the thrust for speedy swimming.
Like other reptiles Ichthyosaurs were air-breathers. They nostrils were placed just in front of they eyes, and they would hold their breath while diving to hunt for prey.
Due to remarkable preservation of some fossils has aloud amazing details and study of the Ichthyosaur skin. From these fossils show the skin of an Ichthyosaur was smooth, not scaly. In addition there is also evidence that they gave birth to live young rather than egg-laying, with many fossils of young developing within the mother’s body. There are even remarkable specimens of babies being born tail first, just as morden whales and dolphins.