Anaspida

Anaspida is an extinct group of jawless fish that lived during the Silurian and Devonian periods. These primitive vertebrates are characterized by their lack of paired fins and the presence of a distinct head shield. Their bodies were typically elongated and covered in small scales or bony plates. Anaspids were marine animals, inhabiting shallow coastal waters.

Fossil evidence suggests that Anaspida were likely bottom-dwellers, feeding on detritus or small invertebrates found in the sediment. Their mouth was positioned ventrally, indicating a bottom-feeding lifestyle. The exact phylogenetic relationships of Anaspida within the broader context of vertebrate evolution are still debated among paleontologists. However, they are generally considered to be an early offshoot of the jawless fish lineage, distinct from other groups like the osteostracans and conodonts.

Notable genera within Anaspida include Birkenia, found in Scotland, and Pterolepis. These fossils provide valuable insights into the early diversification of vertebrates and the evolutionary pressures that shaped early fish. The Anaspida represent a significant branch in the tree of life, showcasing early adaptations for aquatic life before the evolution of jaws and more complex fin structures. Their extinction marks the end of a distinct chapter in early vertebrate history.