Galeaspida

Galeaspida (from Latin, 'Helmet shields') is an extinct taxon of jawless marine and freshwater fish. The name is derived from galea, the Latin word for helmet, and refers to their massive bone shield on the head. Galeaspida lived in shallow, fresh water and marine environments during the Silurian and Devonian times (430 to 370 million years ago) in what is now Southern China, Tibet and Vietnam. Superficially, their morphology appears more similar to that of Heterostraci than Osteostraci, there being currently no evidence that the galeaspids had paired fins. A galeaspid Tujiaaspis vividus from

Dunyu (meaning "shield fish" in Hanyu Pinyin) is an extinct genus of eugaleaspidiform galeaspid known from the Silurian of Yunnan, southwestern China. Two species are known: D longiforus, the type species and D. xiushanensis, which was initially named as a species of Eugaleaspis. The type specimen of D. longiforus is IVPP V 17681, a complete cephalic shield prepared by C. H. Xiong, and the holotype of D. xiushanensis is IVPP V 6793.1, another complete cephalic shield.