Pteraspidomorphi
Encyclopedia
Pteraspida is an extinct class of early jawless fish. The fossils show extensive shielding of the head. Some species may have lived in fresh water.
The taxon contains the subgruops Heterostraci
, Astraspida, Arandaspida.
The taxon contains the subgruops Heterostraci
Heterostraci
Heterostraci is an extinct class of jawless vertebrate that lived primarily in marine and estuary environments. They arose during the Ordovician, and all, save for the Psammosteids, became extinct during the late Devonian...
, Astraspida, Arandaspida.