Protopteraspididae Temporal range: Early Devonian
Protopteraspis gosseleti
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Infraphylum:	Agnatha
Class:	†Pteraspidomorphi
Subclass:	†Heterostraci
Order:	†Pteraspidiformes
Family:	†Protopteraspididae
Genera
Protopteraspis Doryaspis Escharaspis Miltaspis Stegobranchiaspis Unkaraspis "Trygonaspis"

Protopteraspididae is an extinct family of pteraspidid heterostracan agnathans. Fossils of the various genera are found in early Devonian-aged marine strata. Protopteraspidids were once thought to represent a taxon of basal pteraspidids (hence "proto") but recent evaluations demonstrate that Protopteraspididae is a paraphyletic group of various transitional forms representing a gradual transition between the more advanced Pteraspoidei (comprising Pteraspididae, Gigantaspis and Protaspididae),^[1] and the anchipteraspidids and the Psammosteids.

Protopteraspids are found in Lower Devonian marine strata of the Western United States, Northern Canada, England, France, Belgium, Svalbard, Norway, and Podolia, Ukraine.^[2]

This genus is known from several species from Lower Devonian England, France and Belgium

This is a genus of aberrant pteraspidids with lower lips elongated into long, dagger-like organs of unknown function. The various species are primarily restricted to the Lower Devonian strata of Svalbard.

"Trygonaspis" is a nomen nudum given to a well-preserved complete armor that strongly resembles Protopteraspis in form, but with a long, recurved dorsal spine, and orbital plates that have bookshelf-like extensions. The only known specimen was found in Northern Canada.^{[citation needed]}

1. Palaeos Vertebrates entry on order Pteraspidiformes

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