Galeaspida
From Freepedia
Galeaspida (galeaspids) are an extinct taxon of jawless marine fish and a subgroup of the Cephalaspidomorphi, which are itself a subgroup of the vertebrate. They lived in Silurian and Devonian times (430 to 370 million years ago). All fossils were found in Asia. Galeaspids are separated in Eugaleaspidiformes and Polybranchiaspidida. The name Galeaspida is derived from a latin word for helmet, galea. This refers to their massive bone shield on the head.
