Pterichthyodes is a genus of placoderm fishes from the Devonian Period. They had heavily armored heads and forbodies while their tails ere scaly and unarmored. Their length ranged from 8 inches (20 cm) to 12 inches (30 cm). They were members of the earliest known vertebrates to possess jaws although they had grinding plates rather than teeth. The location of the eyes on the upper portion of the head and the flattened trunk shield indicated that they were body dwellers, living in the bottoms of lakes where they may have “crawled” using their pectoral appendages, browsing the lake bottom for decaying detritus. It is also theorized that the appendages were used to bury itself in the bottom sediments.
Pterichthyodes, placoderm fishes