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Origin of Vertebrates Fig 013.jpg
Thyestes verrucosus, natural size. The Origin of Vertebrates by Walter Holbrook Gaskell 1908, Fig. 13, from Woodward)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Janvier 1996

Thyestiida is an order of bony-armored jawless fish in the extinct vertebrate class Osteostraci. [2]

Vertebrate subphylum of chordates

Vertebrates comprise all species of animals within the subphylum Vertebrata. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,276 species described. Vertebrates include the jawless fishes and jawed vertebrates, which include the cartilaginous fishes and the bony fishes.

Osteostraci class of fishes (fossil)

The class Osteostraci is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian.

The osteostracans reconstructed here belong to the major clade Cornuata, whose generalised morphology is exemplified by the zenaspidid Zenaspis (bottom left). Some highly derived head-shield morphologies are exemplified by the benneviaspidids Hoelaspis (top right) and Tauraspis (top left), or the thyestiid Tremataspis (bottom right). The latter, of the family Tremataspididae, has lost the paired fins, possibly as a consequence of an adaptation to burrowing habits. Osteostraci Janvier.gif
The osteostracans reconstructed here belong to the major clade Cornuata, whose generalised morphology is exemplified by the zenaspidid Zenaspis (bottom left). Some highly derived head-shield morphologies are exemplified by the benneviaspidids Hoelaspis (top right) and Tauraspis (top left), or the thyestiid Tremataspis (bottom right). The latter, of the family Tremataspididae, has lost the paired fins, possibly as a consequence of an adaptation to burrowing habits.


Illemoraspis [4]


Auchenaspis [5]






Aestiaspis [6]





Dobraspis [1]











Cladogram, according to Sansom, 2009 [7]

Related Research Articles

Agnatha superclass of fishes

Agnatha is a superclass of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct species. The group is sister to all vertebrates with jaws, known as gnathostomes.

Gnathostomata infraphylum of jawed vertebrates

Gnathostomata are the jawed vertebrates. The term derives from Greek: γνάθος "jaw" + στόμα "mouth". Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates. In addition to opposing jaws, living gnathostomes have teeth, paired appendages, and a horizontal semicircular canal of the inner ear, along with physiological and cellular anatomical characters such as the myelin sheathes of neurons. Another is an adaptive immune system that uses V(D)J recombination to create antigen recognition sites, rather than using genetic recombination in the variable lymphocyte receptor gene.

Cephalaspidomorphi class of chordates

Cephalaspidomorphs are a group of jawless fishes named for Cephalaspis of the osteostracans. Most biologists regard this taxon as extinct, but the name is sometimes used in the classification of lampreys, because lampreys were once thought to be related to cephalaspids. If lampreys are included, they would extend the known range of the group from the Silurian and Devonian periods to the present day.

Anaspida group of extinct jawless vertebrates. Caution: there are other taxa with the same name - snails, beetles and crustaceans

Anaspida is an extinct group of primitive jawless vertebrates that lived primarily during the Silurian period, and became extinct soon after the start of the Devonian. They were classically regarded as the ancestors of lampreys. Anaspids were small marine agnathans that lacked a heavy bony shield and paired fins, but have a striking highly hypocercal tail. They first appeared in the early Silurian, and flourished until the early Devonian, when they disappear from the fossil record.

Hyperoartia class of vertebrates

Hyperoartia or Petromyzontida is a disputed group of vertebrates that includes the modern lampreys and their fossil relatives. 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 Period. Some paleontologists still place these forms among the "ostracoderms" of the class Anaspida, but this is increasingly considered an artificial arrangement based on ancestral traits.

Rhipidistia clade of fishes

The Rhipidistia, also known as dipnotetrapodomorphs are a clade of lobe-finned fishes which include the tetrapods and lungfishes. Rhipidistia formerly referred to a subgroup of Sarcopterygii consisting of the Porolepiformes and Osteolepiformes, a definition that is now obsolete. However as cladistic understanding of the vertebrates has improved over the last few decades a monophyletic Rhipidistia is now understood to include the whole of Tetrapoda and the lungfishes.

Cyclostomata superclass of chordates

Cyclostomata is a group of agnathans that comprises the living jawless fishes: the lampreys and hagfishes. Both groups have jawless mouths with horny epidermal structures that function as teeth, and branchial arches that are internally positioned instead of external as in jawed fishes. The name Cyclostomata means "round mouths".It was named by Joan Crockford Beattie

<i>Cephalaspis</i> genus of fishes (fossil)

Cephalaspis is a probably monotypic genus of extinct osteostracan agnathan vertebrate. It was a trout-sized detritivorous fish that lived in estuaries of the early Devonian.

<i>Boreaspis</i> genus of extinct fishes

Boreaspis is an extinct genus of osteostracan agnathan vertebrate that lived in the Devonian period.

<i>Pituriaspis</i> species of fish (fossil)

Pituriaspis doylei(Doyle's pituri shield) was one of two known species of jawless fish belonging to the Class Pituriaspida, and is the better known of the two. The species lived in estuaries during the Givetian epoch of the Middle Devonian, 390 million years ago in what is now the Georgina Basin of Western Queensland, Australia.

<i>Psarolepis</i> genus of fishes

Psarolepis is a genus of extinct lobe-finned fish which lived around 397 to 418 million years ago. Fossils of Psarolepis have been found mainly in South China and described by paleontologist Xiaobo Yu in 1998. It is not known certainly in which group Psarolepis belongs, but paleontologists agree that it probably is a basal genus and seems to be close to the common ancestor of lobe-finned and ray-finned fishes. In 2001, paleontologist John A. Long compared Psarolepis with Onychodontiform fishes and refer to their relationships.

Cornuata subclass of fishes (fossil)

Cornuata is an extinct taxon of jawless fish that lived in the Early Silurian to Late Devonian.

Benneviaspidida order of fishes (fossil)

Benneviaspidida is an order of osteostracan jawless fishes which lived in the Early Devonian. The fishes in order Benneviaspidida have a flat headshield and are dorsoventrally depressed. The first canal to lateral sensory field bifurcates near the orbit.

<i>Auchenaspis</i> genus of chordates

Auchenaspis salteri is an extinct species of armored jawless fish of the order Thyestiida from the Late Silurian of England. In England, A. salteri's fossils are found in extreme abundance in the Lower Old Red Sandstone strata in Ledbury, Herefordshire.

Evolution of fish The origin and diversification of fish through geologic time

The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include Haikouichthys. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawed fish. Lampreys belong to the Cyclostomata, which includes the extant hagfish, and this group may have split early on from other agnathans.

This list of fossil fish species is a list of taxa of fish that have been described during the year 2012. The list only includes taxa at the level of genus or species.

<i>Janaspis</i> genus of fishes (fossil)

Janaspis is an extinct genus of osteostracan, that lived in the early Devonian period in Britain. It is characterised by a number of features of its armoured headshield, including the presence of raised rims around its eyes, the shape of its lateral and median fields, its prominent dorsal spine, fairly long cornual processes and ornamentation. Janaspis was fairly small compared with other osteostracans, with a headshield measuring less than 60mm.

Zenaspididae family of fishes (fossil)

Zenaspididae is an extinct family of jawless fish in the order Zenaspida.

Ateleaspididae family of fishes (fossil)

Ateleaspididae is a prehistoric jawless fish family in the class Osteostraci.


  1. 1 2 A new tremataspidid (Vertebrata, Osteostraci, Thyestiida) from the Devonian of northern Urals, with remarks on tannuaspidids. Elga Mark-Kurik and Philippe Janvier, Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 01/1997; 206(3), pages 405-421
  2. The origin and early evolution of the Osteostraci (Vertebrata): A phylogeny for the Thyestiida. Robert S. Sansom, Journal of Systematic Palaeontology, Volume 6, Issue 3, 2008, pages 317-332, doi : 10.1017/S1477201907002386
  3. Janvier, Philippe (1997) Osteostraci The Tree of Life Web Project.
  4. The anatomy, affinity and phylogenetic significance of Ilemoraspis kirkinskayae (Osteostraci) from the Devonian of Siberia. Robert S. Sansom, Sergei A. Rodygin and Philip C. J. Donoghue, Journal of Vertebrate Paleontology, Volume 28, Issue 3, 2008, pages 613-625, doi:10.1671/0272-4634(2008)28[613:TAAAPS]2.0.CO;2
  5. A review of the problematic Osteostracan genus Auchenaspis and its role in Thyestidian evolution. Robert Sansom, Palaeontology, Volume 50, Issue 4, pages 1001–1011, July 2007, doi:10.1111/j.1475-4983.2007.00686.x
  6. New data on the exoskeleton of the osteostracan genus Aestiaspis (Agnatha) from the Silurian of Saaremaa Island (Estonia) and the Severnaya Zemlya Archipelago (Russia). O. B. Afanassieva and T. Märss, Paleontological Journal February 2014, Volume 48, Issue 1, pages 74-78, doi:10.1134/S003103011401002X
  7. Sansom, R. S. (2009). "Phylogeny, classification and character polarity of the Osteostraci (Vertebrata)". Journal of Systematic Palaeontology. 7: 95–115. doi:10.1017/S1477201908002551.
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