Anaspida

thumb|254px|right|Anaspids are characterized by a large, tri-radiate spine (red) posteriorly to the series of branchial openings. It is assumed that the most primitive anaspids, such as [[Pharyngolepis (top), possessed a long, ribbon-shaped, ventrolateral fin-fold (green). More advanced forms, such as Rhyncholepis (bottom), possessed a shorter paired fin-fold (green) and enlarged, spine-shaped, median dorsal scutes. – Philippe Janvier]]

Anaspida ("shieldless ones") is an extinct group of jawless fish that existed from the early Silurian period to the late Devonian period. They were classically regarded as the ancestors of lampreys, but this is denied in recent phylogenetic analysis, although some analysis show these group would be at least related. Anaspids all had prominent, laterally placed eyes with no scleral ring, with the gills opened as a row of holes along either side of the animal, typically numbering anywhere from 6-15 pairs. The major synapomorphy for the anaspids is the large, tri-radiate spine behind the series of the gill openings. Class Anaspida now consists of two orders, the monogeneric Lasaniida, which contains the genus Lasanius and represents a basal anaspid group, and Birkeniida, which contains all other recognized anaspid taxa. Birkeniida is further divided into several families, including Birkeniidae, Pterygolepididae, Rhyncholepididae and Pharyngolepididae, which contain those taxa known from whole body fossils (in addition to several taxa known only from scales) and the family Septentrioniidae, whose subtaxa are known exclusively from scales. are considered to be Birkeniida incertae sedis.

Some recent studies have suggested that anaspids are stem-cyclostomes, more closely related to hagfish and lampreys than to jawed fish.

A newer taxonomy based on the work of Mikko's Phylogeny Archive, Nelson, Grande and Wilson 2016 and van der Laan 2018.

thumb|Life reconstruction of Lasanius problematicus

Class †Anaspida Janvier 1996 non Williston 1917
Order †Endeiolepidiformes Berg 1940
Family †Endeiolepididae Stensiö 1939 corrig.
Genus †Endeiolepis Stensiö 1939
Order †Birkeniiformes Berg 1940
Genus †Cowielepis Blom 2008
Genus †Hoburgilepis Blom, Märss & Miller 2002
Genus †Kerreralepis Blom 2012
Genus †Maurylepis Blom, Märss & Miller 2002
Genus †Rytidolepis Pander 1856
Genus †Schidiosteus Pander 1856
Genus †Silmalepis Blom, Märss & Miller 2002
Genus †Vesikulepis Blom, Märss & Miller 2002
Family †Pharyngolepididae Kiær 1924 corrig.
Genus †Pharyngolepis Kiaer 1911
Family †Pterygolepididae Obručhev 1964 corrig.
Genus †Pterygolepis Cossmann 1920 [Pterolepis Kiaer 1911 non Rambur 1838 non De Candolle ex Miquel 1840; Pterolepidops Fowler 1947]
Family †Rhyncholepididae Kiær 1924 corrig.
Genus †Rhyncholepis Kiær 1911 non Miquel 1843 non Nuttall 1841
Family †Tahulalepididae Blom, Märss & Miller 2002
Genus †Tahulalepis Blom, Märss & Miller 2002
Genus †Trimpleylepis Miller, Märss & Blom 2004
Family †Lasaniidae Goodrich 1909
Genus †Lasanius Traquair 1898
Family †Ramsaasalepididae Blom, Märss & Miller 2003
Genus †Ramsaasalepis Blom, Märss & Miller 2003
Family †Birkeniidae Traquair 1899
Genus ?†Vilkitskilepis Märss 2002
Genus †Ctenopleuron Matthew 1907
Genus †Saarolepis Robertson 1945 [Anaspis Robertson 1941 non Geoffroy 1762 non Thomson 1893]
Genus †Birkenia Traquair 1898
Family †Septentrioniidae Blom, Märss & Miller 2002
Genus †Liivilepis Blom, Märss & Miller 2002
Genus †Manbrookia Blom, Märss & Miller 2002
Genus †Ruhnulepis Blom, Märss & Miller 2002
Genus †Spokoinolepis Blom, Märss & Miller 2002
Genus †Septentrionia Blom, Märss & Miller 2002

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