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Chondrostei Temporal range: Triassic–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Atlantic sturgeon, Acipenser oxyrinchus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Subclass:	Chondrostei Müller, 1844
Orders
See text

Chondrostei is a group of non-neopterygian ray-finned fish. While the term originally referred to the paraphyletic grouping of all non-neopterygian ray-finned fish, it was redefined by Patterson in 1982 to be a clade comprising the Acipenseriformes (which includes sturgeon and paddlefish) and their extinct relatives.

Taxa commonly suggested to represent relatives of the Acipenseriformes include the Triassic marine fish Birgeria and the Saurichthyiformes, but their relationship with the Acipenseriformes has been strongly challenged on cladistic grounds. Coccolepididae, a group of small weakly ossified Jurassic and Cretaceous fish found in both marine and freshwater environments, have also been suggested to be close relatives of the Acipenseriformes. However, this has never been subject to cladistic analysis. Near & Thacker (2024) also recovered the ptycholepiform Boreosomus as a stem-acipenseriform.

The following taxa are known:

• Subclass Chondrostei
  • Genus †Eochondrosteus
  • Order †Chondrosteiformes
    • Family †Chondrosteidae
  • Order Acipenseriformes
    • Family †Peipiaosteidae
    • Suborder Acipenseroidei
      • Family Acipenseridae
      • Family Polyodontidae
• Disputed taxa include:
  • Genus †Birgeria
  • Family †Coccolepididae
  • Order †Saurichthyiformes
  • Order †Ptycholepiformes

References

1. ^ Olive, Sébastien; Taverne, Louis; López-Arbarello, Adriana (March 2019). "A new genus of coccolepidid actinopterygian from the Cretaceous Iguanodon-bearing locality of Bernissart, Belgium". Cretaceous Research. 95: 318–335. doi:10.1016/j.cretres.2018.11.020. S2CID 134207366.
2. ^ Argyriou, Thodoris; Giles, Sam; Friedman, Matt; Romano, Carlo; Kogan, Ilja; Sánchez-Villagra, Marcelo R. (December 2018). "Internal cranial anatomy of Early Triassic species of †Saurichthys (Actinopterygii: †Saurichthyiformes): implications for the phylogenetic placement of †saurichthyiforms". BMC Evolutionary Biology. 18 (1): 161. doi:10.1186/s12862-018-1264-4. ISSN 1471-2148. PMC 6211452. PMID 30382811.
3. ^ Near, Thomas J; Thacker, Christine E (18 April 2024). "Phylogenetic classification of living and fossil ray-finned fishes (Actinopterygii)". Bulletin of the Peabody Museum of Natural History. 65. doi:10.3374/014.065.0101.
4. Nelson, Joseph S.; Grande, Terry C.; Wilson, Mark V. H. (2016-02-22). Fishes of the World. Wiley. ISBN 978-1-118-34233-6.

v t e Chondrostei
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Clade: Actinopteri Actinopterygii see Actinopterygii Chondrostei see below↓ Chondrostei
Chondrostei †Birgeria? †Errolichthys? †Gualolepis? †Neochallaia †Bobasatraniiformes? †Guildayichthyidae? †Saurichthyiformes? †Coccolepididae Barbalepis Coccolepis Condorlepis Iyalepis Morrolepis Plesiococcolepis Sunolepis Toarcocephalus Acipenseriformes †Cylindracanthus? †Eochondrosteus †Chondrosteidae Chondrosteus Gyrosteus Strongylosteus †Peipiaosteidae Liaosteus Peipiaosteus Spherosteus Stichopterus Yanosteus Acipenseroidei Polyodontidae †Crossopholis †Paleopsephurus †Parapsephurus Polyodon †Protopsephurus †Psephurus †Pugiopsephurus Acipenseridae Acipenser †Anchiacipenser †Engdahlichthys Huso †Priscosturion †Protoscaphirhynchus Pseudoscaphirhynchus Scaphirhynchus

v t e Evolution of fish
Fish Timeline of fish evolution
Forerunners	Basal member †Pikaia Cephalochordate †Cathaymyrus Lancelet Olfactores †Haikouella Tunicate †Myllokunmingiidae? (†Haikouichthys, †Myllokunmingia) †Zhongxiniscus?
Jawless fish	Cyclostomata Hagfish Hyperoartia Lamprey †Conodonts †Protoconodonta? †Paraconodontida †Conodonta †Ostracoderms †Pteraspidomorphi †Thelodonti †Anaspida †Cephalaspidomorphi †Galeaspida †Pituriaspida †Osteostraci
Jawed fish	†Placoderms †Antiarchi †Arthrodira †Brindabellaspida †Petalichthyida †Phyllolepida †Ptyctodontida †Rhenanida †Acanthothoraci †Pseudopetalichthyida? †Stensioellida? †Acanthodii †Acanthodiformes †"Climatiiformes" †Diplacanthiformes †Ischnacanthiformes Cartilaginous Elasmobranchii †Ctenacanthiformes †Hybodontiformes †Phoebodontiformes †Xenacanthida Ray Shark Holocephali †Eugeneodontida †Iniopterygiformes †Petalodontiformes †Symmoriiformes Chimaera Bony Lobe-finned †Onychodontiformes Coelacanth Rhipidistia †Porolepiformes Lungfish Tetrapodomorpha Ray-finned †"Palaeonisciformes" Cladistia Polypteriformes Chondrostei Acipenseriformes Neopterygii †Pycnodontiformes Halecomorphi Ginglymodi Teleost
Lists	Lists of prehistoric fish spiny sharks placoderms cartilaginous bony lobe-finned List of transitional fossils
Related	Prehistoric life Transitional fossils Vertebrate paleontology
† extinct

• Chondrostei
• Extant Silurian first appearances
• Paraphyletic groups