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  • noun

Synonyms for Heterostraci

extinct group of armored jawless fishes or fish-like vertebrate

References in periodicals archive ?
The taxon was initially recognized as a suborder by Kiaer (1932), who named it the Cyathaspida and included it with the suborders Psammosteida and Pteraspida within the order Heterostraci.
At first psammosteids sensu stricto (from Drepanaspis to Psammosteus) in the group Heterostraci were proposed to form the families Drepanaspidae and Psammosteidae (Traquair 1900; Brotzen 1936; Berg 1940; Obruchev 1941) or only the family Drepanaspidae (Stensio 1927), or only the family Psammosteidae (Woodward 1910; Gross 1937; Berg 1955).
Insufficient knowledge has hindered phylogenetic study of the group Heterostraci as a whole, so there has been uncertainty about its relationships with other tessellated heterostracans (e.