undifferentiated rock units

Paleontology and geology

Most of Arizona was under a shallow sea during the Devonian Period, although land plants found in some areas indicate that lowland terrestrial conditions were also present. The shallow seas were home to a variety of typical Paleozoic animals. Armored fish (placoderms) hunted the waters above the sea floor. Corals, brachiopods, gastropods, and bryozoans lived on the Devonian sea floor.