PHYTOSAUR

extinct, heavily armoured, semiaquatic reptile restricted to the Late Triassic (230 to 208 million years ago). Although they were not ancestral to the crocodiles, in many ways the phytosaurs resembled the modern crocodiles and probably had similar habits. The long and pointed jaws were armed with numerous sharp teeth; it is probable that the phytosaurs preyed largely upon fish. The nostrils in the phytosaurs were set in a mound high on the skull near the eyes, an adaptive feature related to an aquatic existence that allowed the animal to open its mouth underwater without drowning. The greater development of the hind limbs than of the forelimbs indicated that the phytosaurs descended from bipedal reptilian ancestors and reverted to a quadrupedal pose. Phytosaurs were well able to move about on land. Phytosaurian fossils occur in North America, Europe, and India, but their remains have not been found in the southern continents. Familiar genera of phytosaurs include Rutiodon and Phytosaurus, the genus that gives its name to the group as a whole. Rutiodon was more than 3 m (10 feet) long; its skull alone was about 1 m (3.5 feet) long.