Phyllolepis

Phyllolepis was a genus of placoderms, an extinct group of armored fish that lived during the Devonian period, approximately 400 to 359 million years ago. Placoderms, meaning "plate-skin," were characterized by heavy bony armor, particularly around their heads and the front of their bodies, while their tails were free and heterocercal.1

The placoderms flourished for about 60 million years, with their peak success occurring in the middle Devonian. However, the evolution of other, more advanced fish groups led to their eventual extinction by the end of the Devonian period. Little is known about their ancestors, but their evolutionary advances included the development of jaws and fins.1