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Hyperoartia
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, fish-like animals with hypocercal tails that lived during the Late Devonian
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. 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
Cyclostomata
together with the Myxini (hagfishes). More recently, it has been proposed that the Myxini
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
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
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
Hyperoartia
may therefore extend back to the early Paleozoic, if not earlier.

Mayomyzon pickoensis

Placed in this group are at present:[3]

†Jamoytiiformes

†Jamoytiidae White 1946

Jamoytius kerwoodi
Jamoytius kerwoodi
White 1946

†Endeiolepidiformes Berg 1940

†Endeiolepididae Stensio 1939

Endeiolepis aneri Stensio 1939

†Euphanerida

†Euphaneropidae Woodward 1900

†Euphanerops longaevus Woodward 1900 [Legendrelepis Arsenault & Janvier 1991; Legendrelepis parenti Arsenault & Janvier 1991] † Cornovichthys blaauweni
Cornovichthys blaauweni
Newman & Trewin 2001

Petromyzontimorpha

Petromyzontiformes
Petromyzontiformes
(Lampreys)

References[edit]

^ Janvier, Philippe. "Palaeontology: Modern look for ancient lamprey". Nature. 443 (7114): 921–924. doi:10.1038/443921a. PMID 17066021.  ^ 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.  ^ Haaramo, Mikko (2003). "Petromyzontidae - lampreys". in Mikko's Phylogeny Archive. Retrieved November 25, 2013. 

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Extant chordate classes

Kingdom Animalia (unranked) Bilateria Superphylum Deuterostomia

Cephalochordata

Leptocardii (lancelets)

O l f a c t o r e s

Urochordata (tunicates)

Ascidiacea
Ascidiacea
(sea squirts) Appendicularia (larvaceans) Thaliacea
Thaliacea
(pyrosomes, salps, doliolids)

Craniata (Vertebrates + Myxini) (fish + Tetrapods)

Agnatha
Agnatha
(jawless fish)

Cyclostomata

Myxini
Myxini
(hagfish) Hyperoartia
Hyperoartia
(lampreys)

Gnathostomata (jawed vertebrates)

Chondrichthyes
Chondrichthyes
(cartilaginous fish: sharks, rays, chimaeras)

Osteichthyes (bony fish)

Actinopterygii
Actinopterygii
(ray-finned fish)

Sarcopterygii (lobe-finned fish)

Actinistia
Actinistia
(coelacanths)¹

R h i p i d i s t i a

Dipnoi (lungfish)¹

T e t r a p o d a

Amphibia (amphibians)

A m n i o t a

Synapsida

Mammalia (mammals)

Sauropsida (withal Diapsida)

Lepidosauria

Rhynchocephalia
Rhynchocephalia
(tuatara)² Squamata
Squamata
(scaled reptiles)²

Archelosauria

Testudines (turtles)²,³

Archosauria

Crocodilia
Crocodilia
(crocodilians)² Aves (birds)

¹subclasses of Sarcopterygii ²orders of class Reptilia (reptiles) ³traditionally placed in Anapsida italic are paraphyletic groups

Taxon identifiers

Wd: Q188549 EoL: 42349130 Fossilworks: 91450

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