Hyperoartia or Petromyzontida is a disputed group of vertebrates that includes the modern lampreys and their fossil relatives.[1][2] Examples of hyperoartians from early in their fossil record are Endeiolepis and Euphanerops (which possessed a calcified branchial basket),[3] fish-like animals with hypocercal tails that lived during the Late Devonian Period. Some paleontologists still place these forms among the "ostracoderms" (jawless armored fishes) of the class Anaspida, but this is increasingly considered an artificial arrangement based on ancestral traits.

Temporal range: 416–0 Ma Silurian - Recent
Mayomyzon, a Carboniferous lamprey
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Infraphylum: Agnatha
Superclass: Cyclostomi
Class: Hyperoartia
Müller 1844
  • Petromyzontomorphi sensu Benton 2005

Placement of this group among the jawless vertebrates is a matter of dispute. While today enough fossil diversity is known to make a close relationship among the "ostracoderms" unlikely, this has muddied the issue of the Hyperoartia's closest relatives. Traditionally the group was placed in a superclass Cyclostomata together with the Myxini (hagfishes). More recently, it has been proposed that the Myxini are more basal among the skull-bearing chordates, while the Hyperoartia are retained among vertebrates. But even though this may be correct, the lampreys represent one of the oldest divergences of the vertebrate lineage, and whether they are better united with some "ostracoderms" in the Cephalaspidomorphi, or not closer to these than to e.g. to other "ostracoderms" of the Pteraspidomorphi, or even the long-extinct conodonts, is still to be resolved. Even the very existence of the class Hyperoartia is disputed, with some analyses favoring a treatment of the "basal Hyperoartia" as a monophyletic lineage Jamoytiiformes that may in fact be very close to the ancestral jawed vertebrates.

The only hyperoartians surviving today are lampreys, classified in the Petromyzontiformes. The discovery of the fossil Priscomyzon pushed back the oldest known occurrence of true lampreys to the Late Devonian. The evidence of phylogeny, however, suggests the lamprey lineage diverged much earlier from other vertebrates, rather than arising from among the "ostracoderms". The origin of Hyperoartia may therefore extend back to the early Paleozoic, if not earlier.

Mayomyzon pickoensis

Taxonomy and PhylogenyEdit

Placed in this group are at present: Mikko's Phylogeny Archive,[4] Nelson, Grande & Wilson 2016[5] and van der Laan 2018.[6]


?†Hardistiella montanensis Janvier & Lund 1983


Mayomyzon pieckoensis Bardack & Zangerl 1962


?†Pipiscius zangerli Bardack & Richardson 1977

Priscomyzon riniensis Gess, Coates & Rubidge 2006

Mesomyzon mengae Chang, Zhang & Miao 2006


Geotria Gray 1851 (pouched lamprey)


Mordacia Gray 1853 (southern topeyed lampreys)

Petromyzontidae (Northern lampreys)


  1. ^ Janvier, Philippe (2006). "Palaeontology: Modern look for ancient lamprey". Nature. 443 (7114): 921–924. doi:10.1038/443921a. PMID 17066021. S2CID 28217800.
  2. ^ Osório, Joana; Rétaux, Sylvie (2008-02-15). "The lamprey in evolutionary studies". Development Genes and Evolution. 218 (5): 221–235. doi:10.1007/s00427-008-0208-1. ISSN 0949-944X. PMID 18274775. S2CID 6451999.
  3. ^ Hirasawa, T; Oisi, Y; Kuratani, S (2016). "Palaeospondylus as a primitive hagfish". Zoological Letters. 2 (1): 20. doi:10.1186/s40851-016-0057-0. PMC 5015246. PMID 27610240.
  4. ^ Haaramo, Mikko (2003). "Petromyzontidae - lampreys". In Mikko's Phylogeny Archive. Retrieved November 25, 2013.
  5. ^ Nelson, Joseph S.; Grande, Terry C.; Wilson, Mark V. H. (2016). Fishes of the World (5th ed.). John Wiley & Sons. ISBN 9781118342336.
  6. ^ van der Laan, Richard (2016). "Family-group names of fossil fishes". {{cite journal}}: Cite journal requires |journal= (help)