# List of acanthodian genera

This list of acanthodian genera is an attempt to create a comprehensive listing of all genera that have ever been included in the subclass Acanthodii, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomina dubia), or were not formally published (nomina nuda), as well as junior synonyms of more established names, and genera that are no longer considered acanthodians. Not counting their descendants, the modern chondricthyans, all acanthodians are extinct. Extinct genera are marked with a dagger (†)

## Naming conventions and terminology

Naming conventions and terminology follow the International Code of Zoological Nomenclature. Technical terms used include:
* Junior synonym: A name which describes the same taxon as a previously published name. If two or more genera are formally designated and the type specimens are later assigned to the same genus, the first to be published (in chronological order) is the senior synonym, and all other instances are junior synonyms. Senior synonyms are generally used, except by special decision of the ICZN, but junior synonyms cannot be used again, even if deprecated. Junior synonymy is often subjective, unless the genera described were both based on the same type specimen.
* Nomen nudum (Latin for "naked name"): A name that has appeared in print but has not yet been formally published by the standards of the ICZN. Nomina nuda (the plural form) are invalid, and are therefore not italicized as a proper generic name would be. If the name is later formally published, that name is no longer a nomen nudum and will be italicized on this list. Often, the formally published name will differ from any nomina nuda that describe the same specimen.
* Nomen oblitum (Latin for "forgotten name"): A name that has not been used in the scientific community for more than fifty years after its original proposal.
* Preoccupied name: A name that is formally published, but which has already been used for another taxon. This second use is invalid (as are all subsequent uses) and the name must be replaced. As preoccupied names are not valid generic names, they will also go unitalicized on this list.
* Nomen dubium (Latin for "dubious name"): A name describing a fossil with no unique diagnostic features. As this can be an extremely subjective and controversial designation, this term is not used on this list.

## The List

| Genus | Status | Age | Location | Notes | Images |
| †Acanthacanthus | Valid. | Early Lochkovian (earliest Devonian). | Severnaya Zemlya, Russia. | A vesperaliid based on scales. | |
| †Acanthodopsis | Valid. | Carboniferous. | Europe, Australia. | An unusual acanthodid with tooth-like ossifications on its jaws. | |
| †Acanthopora | Valid. | Early Lochkovian (earliest Devonian). | Severnaya Zemlya, Russia. | A small ischnacanthid similar to Poracanthodes. | |
| †Acanthospina | Valid. | Early Lochkovian (earliest Devonian). | Severnaya Zemlya, Russia. | A probable ischnacanthiform with scales similar to hybodontiform sharks. | |
| †Acanthodes | Valid. | Devonian? to Cisuralian (Early Permian). | Europe, North America, China? | One of the most well-known acanthodians, a filter-feeding acanthodid acanthodiform. | |
| †Acritolepis | Valid. | Early Lochkovian (earliest Devonian). | Severnaya Zemlya, Russia. | Namesake of the ischnacanthiform family Acritolepidae. | |
| †Aganacanthus | Valid or junior synonym. | Mississippian / Early Carboniferous. | Scotland. | A possible gyracanthid known from a single worn fin spine, may be an indeterminate gnathostome or a junior synonym of Gyracanthus. | |
| †Ankylacanthus | Valid. | Emsian (Early Devonian). | Canada. | An acanthodian based on fin spines, possibly one of the oldest gyracanthids. | |
| †Antacanthus | Nomen dubium? | Mississippian / Early Carboniferous. | Belgium. | A possible gyracanthid known from a single fin spine. | |
| †Antarctonchus | Valid. | Givetian (Middle Devonian). | Antarctica. | An Antarctic acanthodian based on fin spine casts. | |
| †Apateacanthus | Valid. | Late Devonian. | New York, U.S.A. | Based on a fin spine with large denticles, sometimes mistaken for an ischnacanthiform jaw. | |
| †Archaeacanthus | Valid. | Eifelian to Givetian (Middle Devonian). | Europe. | Based on fin spines common in Middle Devonian strata of Siberia and Northeastern Europe. | |
| †Arcticacanthus | Valid. | Early Lochkovian to Emsian (Early Devonian). | Severnaya Zemlya, Russia. | A possible ischnacanthid based on scales. | |
| †Arenaceacanthus | Valid. | Wenlock to early Pridoli (Silurian). | Lithuania. | A probable ischnacanthid based on scales, common in Lithuania. | |
| †Atopacanthus | Valid. | Eifelian to Early Famennian (Middle Devonian to Late Devonian). | North America, Europe, Iran. | A widespread and long-lived ischnacanthid. | |
| †Brachyacanthus | Valid. | Lochkovian (Early Devonian). | Scotland. | A small climatiid from the Lower Old Red Sandstone of Scotland. | |
| †Bracteatacanthus | Valid. | Latest Pridoli (latest Silurian). | Lithuania. | A probable ischnacanthid based on scales. | |
| †Brochoadmones | Valid. | Lochkovian (Early Devonian). | Canada. | A deep-bodied and well-preserved "climatiiform" from the Man-On-The-Hill (MOTH) locality in the MacKenzie Mountains of Canada. | |
| †Bryantonchus | Valid. | Emsian (Early Devonian). | U.S.A. | A probable diplacanthiform based on fin spines. | |
| †Byssacanthoides | Valid. | Givetian (Middle Devonian). | Antarctica. | An Antarctic acanthodian based on fin spine casts. | |
| †Cacheacanthus | Valid. | Emsian (Early Devonian). | U.S.A. | Based on ischnacanthid jaw fragments from the western United States. | |
| †Campylodus | Nomen dubium? | Ludlow to Lochkovian? (late Silurian to earliest Devonian)? | Europe. | Jaw fragments probably belonging to indeterminate ischnacanthiforms. | |
| †Canadalepis | Valid. | Lochkovian? to Emsian (Early Devonian). | Asia, Australia, Canada. | A possible climatiid based on scales. | |
| †Carycinacanthus | Junior synonym. | Tournaisian (earliest Mississippian / Carboniferous). | Russia. | A junior synonym of Acanthodes lopatini. | |
| †Cassidiceps | Valid. | Lochkovian (Early Devonian). | Canada. | A toothless, deep-bodied MOTH locality acanthodian with complex head armor. Probably closely related to the acanthodiforms. | |
| †Cheiracanthoides | Valid. | Pridoli to Frasnian (latest Silurian to Late Devonian). | Worldwide. | A widespread and long-lasting possible climatiid based on scales. | |
| †Cheiracanthus | Valid. | Middle Devonian. | Europe. | The fairly common namesake of the acanthodiform family Cheiracanthidae. | |
| †Climatius | Valid. | Lochkovian (Early Devonian). | U.K., Portugal. | The namesake of the family Climatiidae. | |
| †Culmacanthus | Valid. | Givetian to Frasnian (Middle Devonian to Late Devonian). | Australia, Antarctica. | A distinctive diplacanthiform with reduced intermediate spines and large cheek plates. | |
| †Devononchus | Valid. | Givetian to Famennian (Middle Devonian to Late Devonian). | Europe. | Based on fin spines and scales common in the areas corresponding to Baltica. | |
| †Diplacanthus | Valid. | Middle Devonian to Late Devonian. | Scotland, Russia, South Africa, Canada? | The widespread, long-lasting, and fairly common namesake of the family Diplacanthidae and order Diplacanthiformes. | |
| †Doliodus | Valid (non-acanthodian). | Emsian (Early Devonian). | Canada. | A spiny stem-chondrichthyan which acts as a transitional form between acanthodians and non-acanthodian traditional chondrichthyans. | |
| †Eifellepis | Valid. | Emsian to Eifelian (Early Devonian to Middle Devonian). | Germany, Belgium. | An indeterminate acanthodian based on scales. | |
| †Erriwacanthus | Valid. | Pragian (Early Devonian). | U.K., Ukraine. | A climatiid with large and complex spines on its shoulder girdle. | |
| †Endemolepis | Valid. | Pridoli to Lochkovian (latest Silurian to Early Devonian). | Europe. | A possible climatiid based on scales. | |
| †Erymnacanthus | Valid. | Lochkovian (Early Devonian). | Canada. | A medium-sized MOTH locality ischnacanthid. | Erymnacanthus clivus jaw cast |
| †Eupleurogmus | Nomen dubium. | Mississippian / Early Carboniferous? | Australia. | A dubious taxon based on Acanthodes-like scales. | |
| †Euryacanthus | Valid. | Lochkovian (Early Devonian). | Canada. | A medium-sized MOTH locality ischnacanthid. | |
| †Euthacanthus | Valid. | Early Lochkovian (earliest Devonian). | U.K. | A slender acanthodian of uncertain affinities, despite its well-described anatomy. | |
| †Fallodentus | Valid. | Givetian (Middle Devonian). | Scotland. | A cheiracanthid acanthodiform closely related to Homalacanthus. | |
| †Fanjingshania | Valid. | Aeronian (Early Silurian, Llandovery Epoch). | China. | A climatiiform, one of the earliest known acanthodean genus. | Fanjingshania fin spine |
| †Fecundosquama | Valid. | Pridoli (late Silurian). | Lithuania. | A tchunacanthid based on scales. | |
| †Florestacanthus | Valid. | Late Frasnian to early Famennian (Late Devonian). | Colombia. | A diplacanthid diplacanthiform and one of the few acanthodians endemic to northwestern Gondwana (now South America). | |
| †Funicristata | Valid | Silurian (Přidolí) | U.S.A. (Nevada) | An acanthodian of uncertain affinities, based on scales. | |
| †Gemuendolepis | Valid? | Early Devonian. | Germany. | A poorly-described taxon based on scales. | |
| †Ginkgolepis | Valid. | Eifelian to Famennian? (Middle Devonian to Late Devonian). | Estonia, Russia. | A cheiracanthid acanthodiform based on scales. | |
| †Gladbachus | Valid (non-acanthodian?). | Givetian (Middle Devonian). | Germany. | A large filter-feeding stem-chondrichthyan, sometimes positioned among acanthodians despite its very dissimilar anatomy. | |
| †Gladiobranchus | Junior synonym? | Lochkovian (Early Devonian). | Canada. | A well-preserved diplacanthiform which may be synonymous with Uraniacanthus curtus. | |
| †Gomphacanthus | Nomen dubium? | Carboniferous. | England. | A possible gyracanthid based on a worn fin spine. | |
| †Gomphonchoporus | Valid. | Pridoli to Lochkovian (late Silurian to Early Devonian). | Europe, Australia, Canada, Greenland. | A widespread poracanthodid based on scales. | |
| †Gomphonchus | Valid. | Ludlow to Emsian? (late Silurian to Early Devonian). | Europe, Australia?, China? | A widespread ischnacanthid primarily based on scales. | |
| †Granulacanthus | Valid. | Late Wenlock or early Ludlow (Silurian). | Canada. | A possible ischnacanthiform based on distinctive fin spines. | |
| †Grenfellacanthus | Valid. | Latest Famennian (latest Devonian). | Australia. | One of the youngest and largest ischnacanthids, nearly a meter in length. | |
| †Gyracanthides | Valid. | Pragian to Visean (Early Devonian to Mississippian). | Worldwide. | A long-lasting and widespread gyracanthid with flattened fin spines. | |
| †Gyracanthus | Valid. | Lochkovian to Moscovian (Early Devonian to Pennsylvanian) | Europe, North America, Bolivia? | The long-lasting namesake of the family Gyracanthidae. | |
| †Hanilepis | Valid. | Late Ludlow (late Silurian). | China. | An indeterminate acanthodian based on scales. | |
| †Halimacanthodes | Valid. | Frasnian (Late Devonian). | Australia. | A howittacanthid acanthodiform, the only acanthodian known from the Gogo Formation lagerstätte. | |
| †Haplacanthus | Valid. | Eifelian to early Famennian (Middle Devonian to Late Devonian). | Europe, Greenland. | A cheiracanthid acanthodiform based on fin spines common in the areas corresponding to Baltica. | |
| †Helenacanthus | Valid? (non-acanthodian) | Emsian (Early Devonian). | Wyoming, U.S.A. | Has historically been considered acanthodian material, but probably armor from an actinolepid placoderm instead. | |
| †Helolepis | Junior synonym. | Emsian to Eifelian (Early Devonian to Middle Devonian). | Ohio, U.S.A. | A junior synonym of Cheiracanthoides comptus. | |
| †Homacanthus | Junior synonym? | Eifelian (Middle Devonian) to Pennsylvanian? | Europe, North America? | An acanthodian based on fin spines, though many of its species and specimens have been reassigned to other taxa. | |
| †Homalacanthus | Valid. | Frasnian (Late Devonian). | Canada. | A cheiracanthid acanthodiform known to have played a large role in the food chain of the Miguasha Lagerstätte. | |
| †Howittacanthus | Valid. | Frasnian (Late Devonian). | Australia. | The abundant namesake of the acanthodiform family Howittacanthidae. | |
| †Iranolepis | Valid. | Early Frasnian (Late Devonian). | Iran. | A possible climatiid based on scales. | |
| †Ischnacanthus | Valid. | Lochkovian (Early Devonian). | U.K., Portugal. | The abundant namesake of the ischnacanthiforms. | |
| †Kathemacanthus | Valid. | Lochkovian (Early Devonian). | Canada. | A Brochoadmones-like acanthodian from the MOTH locality, with a "necklace" of artichoke-shaped scales similar to those of chondrichthyans. | |
| †Laliacanthus | Valid. | Emsian to Eifelian (Early Devonian to Middle Devonian). | Europe, Saudi Arabia. | A possible climatiid based on scales. | |
| †Latviacanthus | Valid. | "upper Lower Devonian" | Latvia. | A possible climatiid with large ischnacanthiform-like jaw plates. | |
| †Lenacanthus | Valid. | Early Llandovery (earliest Silurian). | Russia. | A tchunacanthid based on scales, one of the earliest acanthodians. | |
| †Lijiangichthys | Valid. | Pragian (Early Devonian). | China. | An indeterminate acanthodian based on scales. | |
| †Lodeacanthus | Valid. | Frasnian (Late Devonian). | Latvia. | A mesacanthid acanthodiform known from a complete growth series. | |
| †Lupopsyrus | Valid. | Lochkovian (Early Devonian). | Canada. | A MOTH locality acanthodian with two rows of enlarged scales on either side of its body. | |
| †Machaeracanthus | Valid. | Late Silurian to Eifelian (Middle Devonian). | Worldwide. | A widespread possible ischnacanthiform which occupies its own monotypic family. | Machaeracanthus fin spines |
| †Machaeraporus | Valid. | Pridoli to Lochkovian (late Silurian to Early Devonian). | Canada, Europe. | A poracanthodid ischnacanthiform based on scales. | |
| †Markacanthus | Valid. | Eifelian to Givetian (Middle Devonian). | Belarus, Scotland. | A fairly typical cheiracanthid acanthodiform. | |
| †Marsdenius | Valid. | Mississippian / Early Carboniferous. | England. | An obscure possible ischnacanthid based on a specimen which is now lost. | |
| †Melanoacanthus | Valid. | Emsian (Early Devonian). | Canada. | A small mesacanthid acanthodiform with broad head plates. | |
| †Mesacanthus | Valid. | Early Devonian to Middle Devonian. | Scotland. | The small but fairly common namesake of the acanthodiform family Mesacanthidae. | |
| †Milesacanthus | Valid. | Pragian to Frasnian (Early Devonian to Late Devonian). | Worldwide. | A widespread diplacanthid diplacanthiform. | |
| †Minioracanthus | Valid. | Eifelian to Givetian (Middle Devonian). | Europe. | An indeterminate acanthodian based on scales. | |
| †Monopleurodus | Valid. | Pridoli (late Silurian). | Estonia. | Poorly-known. | |
| †Monospina | Valid. | Late Pridoli (latest Silurian). | Latvia, Lithuania. | An acritolepid ischnacanthiform based on scales. | |
| †Nerepisacanthus | Valid. | Ludlow to late Pridoli (late Silurian). | Canada. | An acritolepid ischnacanthiform and one of the most well-preserved Silurian acanthodians. | |
| †Nobilesquama | Valid. | Lochkovian to Emsian (Early Devonian). | Russia. | An indeterminate acanthodian based on scales. | |
| †Nodocosta | Valid. | Emsian to Frasnian (Early Devonian to Late Devonian). | Europe, U.S.A. | A possible climatiid based on fin spines. | |
| †Nodonchus | Junior synonym? | Lochkovian (Early Devonian). | England, Saudi Arabia? | Based on fin spines, but may be a junior synonym of Parexus. | |
| †Nostolepis | Valid. | Wenlock to early Frasnian (mid-Silurian to Late Devonian). | Worldwide. | One of the most widespread, long-lasting, and abundant acanthodians based primarily on scales. | |
| †Nostovicina | Valid. | Pridoli to Emsian (late Silurian to Early Devonian). | Worldwide. | A widespread indeterminate acanthodian based on scales and fin spines. | |
| †Obruchevacanthus | Valid. | Late Lochkovian (Early Devonian). | Spain. | A poracanthodid ischnacanthiform closely related to Trundlelepis. | |
| †Obtusacanthus | Valid. | Lochkovian (Early Devonian). | Canada. | An unusual MOTH locality gnathostome, likely an acanthodian closely related to true chondrichthyans. Despite lacking teeth, it was a predator with specialized lip scales. | |
| †Onchus | Valid. | Late Llandovery? to Famennian (early Silurian to Late Devonian). | Europe, North America. | A possible ischnacanthiform based on fin spines; may be one of the oldest known acanthodians. | |
| †Oracanthus | Valid? | Mississippian. | Europe, North America. | A poorly-known gyracanthid based on fin spines. | |
| †Orcadacanthus | Valid. | Middle Devonian. | Scotland. | A small mesacanthid based on species formerly placed in Acanthodes and Mesacanthus. | |
| †Paranostolepis | Valid. | Late Devonian. | Canada. | A poorly-known indeterminate acanthodian based on scales. | |
| †Parexus | Valid. | Lochkovian (Early Devonian). | U.K. | A climatiid with a massive first dorsal fin spine. | |
| †Paucicanthus | Valid. | Lochkovian (Early Devonian). | Canada. | A MOTH locality acanthodian lacking spines on the pectoral and pelvic fins. | |
| †Pechoralepis | Valid. | Pridoli to Givetian (late Silurian to Middle Devonian). | Russia, Antarctica. | An acritolepid ischnacanthiform based on scales. | |
| †Peregrinosquama | Valid. | Lower Emsian (Early Devonian). | Russia. | An indeterminate acanthodian based on scales. | |
| †Persacanthus | Valid. | Frasnian (Late Devonian). | Iran, Russia, North America. | An ischnacanthid very closely related to Atopacanthus. | |
| †Pinnacanthus | Valid. | Emsian (Early Devonian). | Wyoming, U.S.A. | An acanthodian based on fin spines. | |
| †Plectrodus | Valid. | Ludlow (late Silurian). | England. | An ischnacanthid commonly confused with Ischnacanthus. | |
| †Protodus | Valid (non-acanthodian). | Late Pragian to Emsian (Early Devonian). | Canada. | Chondrichthyan teeth originally misidentified as belonging to acanthodiians, due to their similarity to the teeth of a Nostolepis specimen from Scotland. | |
| †Podoliacanthus | Valid. | Pridoli? to Lochkovian (late Silurian? to Early Devonian). | Greenland, Ukraine. | A small ischnacanthid. | |
| †Poracanthodes | Valid. | Ludlow? to Pragian (late Silurian to Early Devonian). | Europe, North America. | Namesake of the ischnacanthiform family Poracanthodidae. | |
| †Promesacanthus | Valid. | Lochkovian (Early Devonian). | Canada. | A mesacanthid acanthodiform from the MOTH locality, with small prepectoral spines similar to "climatiiforms". | |
| †Protogonacanthus | Valid. | Frasnian (Late Devonian). | Germany. | A cheiracanthid acanthodiform preferring a marine environment. | |
| †Pruemolepis | Valid? | Emsian to Eifelian (Early Devonian to Middle Devonian). | Europe. | A possible climatiid based on scales similar to some species of Nostolepis. | |
| †Pseudacanthodes | Valid or junior synonym. | Moscovian (Pennsylvanian / Late Carboniferous). | Czechia. | An eel-like acanthodid acanthodiform, possibly a junior synonym of Traquairichthys. | |
| †Ptomacanthus | Valid. | Lochkovian (Early Devonian). | England, Ukraine. | One of the few non-Acanthodes acanthodians with a well-described braincase and gill system, helping to clarify the group's relations with other fishes. | |
| †Ptychodictyon | Valid. | Emsian to Givetian (Early Devonian to Middle Devonian). | Europe, U.S.A. | A diplacanthid diplacanthiform based on scales. | |
| †Pucapampella | Valid (non-acanthodian?). | Eifelian to Givetian (Middle Devonian). | Bolivia. | A chondrichthyan-like braincase sometimes positioned among acanthodians. | |
| †Radioporacanthodes | Valid. | Ludlow to Emsian (late Silurian to Early Devonian). | Worldwide. | A widespread poracanthodid ischnacanthiform primarily based on scales. | |
| †Rhadinacanthus | Valid. | Emsian to Famennian? (Early Devonian to Late Devonian). | Europe, China, Canada. | A diplacanthid diplacanthiform similar to, but distinct from, Diplacanthus. | |
| †Rockycampacanthus | Valid. | Late Emsian (Early Devonian). | Australia. | A distinctive marine ischnacanthid. | |
| †Rohonilepis | Valid. | Ludlow to Pridoli (late Silurian). | Lithuania, Latvia. | A possible ischnacanthid based on scales. | |
| †Sabrinacanthus | Valid. | Lochkovian (Early Devonian). | England. | A climatiid with a large shoulder girdle. | |
| †Serradentus | Valid. | Late Givetian (Middle Devonian). | Spitsbergen. | A medium-sized ischnacanthiform. | |
| †Sevyacanthus | Valid. | Emsian (Early Devonian). | U.S.A. | A climatiid with complex spine plates. | |
| †Sinacanthus | Valid (non-acanthodian). | Silurian to Early Devonian. | Asia. | Namesake of the sinacanthids, a group of spined gnathostomes which are likely chondrichthyans. | |
| †Striacanthus | Valid. | Pragian to Frasnian (Early Devonian to Late Devonian). | Europe, Australia. | A diplacanthiform based on elongated fin spines. | |
| †Taemasacanthus | Valid. | Late Emsian (Early Devonian). | Australia. | A moderately large marine ischnacanthid. | |
| †Taimyrolepis | Valid. | Pridoli to Lochkovian (late Silurian to Early Devonian). | Russia. | A possible poracanthodid ischnacanthiform based on scales. | |
| †Tareyacanthus | Valid. | Pragian to Emsian (Early Devonian). | Europe, Australia. | A possible climatiid based on scales. | |
| †Tchunacanthus | Valid. | Late Llandovery (early Silurian). | Russia. | A tchunacanthid based on scales. | |
| †Teneracanthus | Valid. | Late Emsian to Famennian (Early Devonian to Late Devonian). | Australia, Belgium. | A mesacanthid acanthodiform closely related to Lodeacanthus. | |
| †Tetanopsyrus | Valid. | Lochkovian (Early Devonian). | Canada. | A distinctive diplacanthiform from the MOTH locality. | |
| †Traquairia | Junior synonym. | Moscovian (Pennsylvanian / Late Carboniferous). | Czechia. | Junior synonym of Traquiairichthys. | |
| †Traquairichthys | Valid. | Moscovian to Leonardian? (Pennsylvanian / Late Carboniferous to Early Permian). | Czechia, Greenland?, Texas, U.S.A.? | An eel-like acanthodid acanthodiform. | |
| †Triazeugacanthus | Valid. | Frasnian (Late Devonian). | Canada. | A mesacanthid acanthodiform from the Miguasha Lagerstätte, with one of the best-known ontogenetic series of all acanthodians. | |
| †Tricuspicanthus | Valid. | Lochkovian (Early Devonian). | Canada. | A small MOTH locality ischnacanthid. | |
| †Trundlelepis | Valid. | Lochkovian to Pragian (Early Devonian). | Australia, Nevada, U.S.A.? | A poracanthodid ischnacanthiform based on scales. | |
| †Uraniacanthus | Valid. | Lochkovian (Early Devonian). | U.K., Canada? | A long-spined gladiobranchid diplacanthiform, sometimes misidentified as an ischnacanthiform. | |
| †Utahacanthus | Valid. | Namurian (early Pennsylvanian / Late Carboniferous). | Utah, U.S.A. | An acanthodid acanthodiform with three prominent otoliths. | |
| †Vernicomacanthus | Valid. | Lochkovian (Early Devonian). | U.K. | A rare climatiid with denticulated fin spines. | |
| †Vesperalia | Valid. | Late Pridoli (late Silurian). | Lithuania. | A vesperaliid based on scales. | |
| †Watsonacanthus | Valid. | Emsian to Eifelian (Early Devonian to Middle Devonian). | Europe, Australia. | A possible climatiid based on scales. | |
| †Westrichus | Valid. | Carboniferous - Permian boundary | Germany | An acanthodiform. | |
| †Wetteldorfia | Valid. | Lochkovian to Eifelian (Early Devonian to Middle Devonian). | Germany, Spain, Australia, Saudi Arabia. | A possible climatiid based on scales. | |
| †Xylacanthus | Valid. | Late Wenlock (mid-Silurian) to Pragian (Early Devonian). | Spitsbergen, Canada. | An ischnacanthid containing both the largest species of acanthodians (X. grandis at 2.5 meters long) and one of the oldest species (X. kenstewarti). | |
| †Yealepis | Valid. | Ludlow (late Silurian). | Australia. | A large but indeterminate acanthodian which seems to lack fin spines. | |
| †Zemlyacanthus | Valid. | Lochkovian (Early Devonian). | Severnaya Zemlya, Russia. | One of the few poracanthodid ischnacanthiforms known from articulated skeletons. | |