Devonian jawless fish

Pteraspis (from 'wing' or 'fin' and 'shield') is an extinct genus of pteraspidid heterostracan jawless fish. It existed from the Lochkovian to Eifelian epochs of the Devonian period in areas that are now the Americas and Europe.

Pteraspidiformes is an extinct order of heterostracan agnathan vertebrates known from extensive fossil remains primarily from Early Devonian strata of Europe and North America, and from Upper Silurian Canada.

Priscomyzon is a genus of extinct lamprey that lived around 360 million years ago during the Famennian (Late Devonian) in a marine or estuarine environment in South Africa. This small agnathan is anatomically similar to the Mazon Creek lampreys, but is some 35 million years older. Its key developments included the first known large oral disc, circumoral teeth and a branchial basket.

Drepanaspis (from 'sickle' and 'shield') is an extinct genus of heterostracan armoured jawless fish from the Early Devonian (approximately 416 - 397 mya). Drepanaspis are assumed to have lived primarily in marine environments and is most commonly characterized by their ray-like, heavily armoured bodies, along with their lack of paired fins and jaws.

Psammosteidae is an extinct family of flattened, benthic heterostracan vertebrates that lived in marine and estuary environments in Europe, Russia & North America. They arose during the Early Devonian, with the first (and best) known genus, Drepanaspis from the Hunsrück lagerstätte. The Psammosteids were the only heterostracans that survived the Upper Frasnian extinction event during the Late Devonian, dying out in the extinction event at the very end of the Devonian. ==References== Palaeos Vertebrates

Doryaspis is an extinct genus of armored jawless fish belonging to the order Pteraspidiformes. It contains five species, all of which are exclusively known from what is now the island of Spitsbergen in the Svalbard archipelago of Norway. The genus lived during the Pragian to Emsian ages of the Early Devonian period. Doryaspis is distinguished from other pteraspidiforms by several unusual features, most notably its narrow, outward-pointing cornual plates and a long, pointed projection near its mouth known as a pseudorostrum.

Furcacauda is a genus of thelodontid agnathan from the Lower Devonian of Canada, and is the type genus of the order Furcacaudiformes. It contains two species, both of which hail from the MOTH locality in the Mackenzie Mountains of the Northwest Territories.

Cometicercus is an extinct genus of furcacaudiform thelodont which lived in the Northwest Territories of Canada during the Early Devonian period. It hails from the MOTH locality in the Mackenzie Mountains. It is only known from its caudal fin and parts of its dorsal surface, including its dorsal fin.'' The scales of Cometicercus'' likely served an anti-parasite role, similar to modern sharks which form large groups and cruise at slow to medium speeds.