Ketaspididae

Ketaspididae is an extinct family of jawless fish that lived during the Silurian period. These armored fish, also known as heterostracans, were characterized by their bony plates covering their heads and anterior bodies. Ketaspidids are distinguished from other heterostracans by specific features of their armor, particularly the arrangement and ornamentation of the head shields. Their mouths were typically ventral, adapted for bottom feeding. Fossil evidence suggests they inhabited shallow marine environments. The group is primarily known from the Devonian period, though their origins can be traced to the Silurian. Ketaspidids represent an important lineage in the early evolution of vertebrates, showcasing the development of exoskeletal structures and diversification within the agnathans. Their fossils are found in various parts of the world, providing insights into the paleogeography of the Silurian and Devonian seas. The exact phylogenetic position of Ketaspididae within the broader classification of jawless fish is a subject of ongoing research, but they are generally considered a diverse and successful group within the heterostracans.