The typical Ichthyosaurus, to give shape to the animal before we do a lot history or behavior, would have been about 6.6ft (2m) long tip to tail. It would have been fairly fast as its dolphin shaped body suggests and probably hunted squid rather than fast fish. Integument impressions from German fossils suggest that Ichthyosaurs had large dorsal (back) fins and a fairly large caudal (tail) fin to propel it through the water. It had large sensitive eyes and sensitive ears as well, breathed oxygen through lungs, not gills, and some fossils even suggest viviparity (live birth) among Ichthyosaurs. Ichthyosaurs were most likely very graceful swimmers very in tune with their environment, some of the first highly successful reptiles to transition back to, and dominate, the ancient oceans.