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Aulopiformes
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| Aulopiformes Temporal range: Early Cretaceous to present[1]
| |
|---|---|
| Variegated lizardfish, Synodus variegatus (Synodontoidei: Synodontidae) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Clade: | Eurypterygii |
| Superorder: | Cyclosquamata |
| Order: | Aulopiformes D. E. Rosen, 1973 |
| Type genus | |
| Aulopus Cloquet, 1816
| |
| Suborders | |
| Synonyms | |
|
Macristiidae (see text) | |
Aulopiformes /ˈɔːləpɪfɔːrmiːz/[a] is a diverse order of marine ray-finned fish consisting of some 15 extant and several prehistoric families with about 45 genera and over 230 species. The common names grinners, lizardfishes and allies, or aulopiforms are sometimes used for this group. They are included in the superorder Cyclosquamata,[b] though modern taxonomists consider this superorder to be unwarranted.
Many extant aulopiforms are deep-sea fishes, with some species recognized as being hermaphroditic, a number of which are able to self-fertilise. Some are benthic, but most are pelagic swimmers (nektonic).[6][7] A clade of Aulopiformes, the suborder Enchodontoidei and its many constituent families, were dominant nektonic fish throughout much of the Late Cretaceous before the extinction of most of their members around the K–Pg event,[1][8] with the Dercetidae surviving for some time in the Cenozoic.[9][10]
Taxonomy
[edit]Past authors have considered aulopiforms to be so distinct as to warrant separation in a monotypic superorder of the Teleostei, the Cyclosquamata. However, monotypic taxa are generally avoided by modern taxonomists if not necessary, and in this case a distinct superorder seems indeed unwarranted: together with the equally dubious superorder "Stenopterygii", the grinners appear to be closely related to some of the Protacanthopterygii, namely, the Salmoniformes (salmon, trout, and relatives), and should perhaps be part of that larger clade. As an alternative, the superorders are sometimes united as an unranked clade named Euteleostei, but in that case the Protacanthopterygii would need to be split further to account for the phylogenetic uncertainty. This would result in a highly cumbersome and taxonomically redundant group of two very small and no less than four monotypic superorders.[6][11]
Description
[edit]
(Chlorophthalmoidei: Chlorophthalmidae)
In general, aulopiform fish have a mixture of advanced and primitive characteristics relative to other teleost fish. Aulopiformes are grouped together (claded) because of common features in the structure of their gill arches; their second pharyngobranchial bone (part of the gill arch) is greatly elongated posterolaterally away from third pharyngobranchial, which lacks a cartilaginous condyle to articulate with the preceding bone, but is contacted by the elongated uncinate process of the second epibranchial. Aulopiforms have a gas bladder which is either vestigial or entirely absent, a hypaxialis muscle that is unusually extended forward at its upper end, attaching to the neurocranium below the spine (perhaps to snap the upper part of the skull down when catching prey), and the position of the maxillary bone. Other features include the position of the pelvic fins far back on the body, the fused medial processes of pelvic girdle, and the presence of an adipose fin (which is also typical for the Protacanthopterygii).[4][6][7]
The larvae of some Aulopiformes are extremely bizarre-looking, with elongated fins, and do not resemble the adult animals. They were not only described as distinct species, but also even separated as genera and finally in a family "Macristiidae" which was allied with various Protacanthopterygii (sensu lato), but the initial assessment – which found "Macristium" to resemble the deepwater lizardfishes (Bathysauridae) in some details – was in fact not far off the mark: "Macristium" species are now known to be the larvae of Bathysaurus, while the supposed other "macristiids" "Macristiella spp." are larvae of the deepsea tripodfish Bathytyphlops.[12]
Several extant aulopiform families have Cretaceous representatives, and phylogenetic evidence indicates that the extant families of the order diversified around the Early Cretaceous, making it rather ancient. These diversification events included the earliest adaptations for deep-sea living, which is common among many extant aulopiform taxa.[1] Below is a timeline indicating fossil evidence for the group:

Classification
[edit]
(Alepisauroidei: Paralepididae)

(Chlorophthalmoidei: Ipnopidae)

(Enchodontoidei: Enchodontidae)

(Giganturoidei: Bathysauridae)
- Suborder Alepisauroidei
- Family Alepisauridae – lancetfishes
- Family Anotopteridae – daggertooths (may belong in Paralepididae)
- Family Evermannellidae – sabertooth fishes
- Family Omosudidae – hammerjaw (sometimes included in Alepisauridae)
- Family Paralepididae – barracudinas
- Family †Polymerichthyidae – an extinct alepisauroid closely related to the daggertooths and lancetfish[13]
- Family Scopelarchidae – pearleyes
- Suborder Chlorophthalmoidei
- Family Bathysauroididae – pale deepsea lizardfish
- Family Bathysauropsidae – lizard greeneyes (sometimes included in Ipnopidae)
- Family Chlorophthalmidae – greeneyes
- Family Ipnopidae – deepsea tripodfishes
- Family Notosudidae – waryfishes
- Suborder †Enchodontoidei (including Halecoidei, Ichthyotringoidei, may belong in Alepisauroidei; fossil)
- Genus †Nardorex (fossil, tentatively placed here)
- Genus †Serrilepis (fossil, tentatively placed here)
- Genus †Yabrudichthys (fossil, tentatively placed here)
- Family †Apateopholidae (fossil)
- Family †Cimolichthyidae (fossil)
- Family †Dercetidae (fossil)
- Family †Enchodontidae (fossil)
- Family †Eurypholidae (fossil)
- Family †Halecidae (fossil)
- Family †Ichthyotringidae (fossil)
- Family †Prionolepididae (fossil)
- Suborder Giganturoidei
- Family Bathysauridae – deepwater lizardfishes
- Family Giganturidae – telescopefishes
- Suborder Synodontoidei
- Family Aulopidae – flagfins
- Family Paraulopidae – "cucumberfishes"
- Family Pseudotrichonotidae – sandliving lizardfishes, sand-diving lizardfishes
- Family Synodontidae – typical lizardfishes
- Suborder incertae sedis
- ?Family †Cheirothricidae (fossil, generally considered indeterminate eurypterygians)[14]
- Genus †Aulopopsis (fossil)[15]
† means extinct.
Footnotes
[edit]- ^ Meaning "Aulopus-shaped", from Aulopus (the type genus) + the standard fish order suffix "-formes"; this ultimately derives from Ancient Greek aulós (αὐλός, "flute" or "pipe") + Latin forma ("external form"), the former in reference to the elongated shape of many aulopiforms.[2][3][4]
- ^ cyclō + squāmātus; "circle scale", referring to the cycloid scales predominant in these fish[5]
References
[edit]- ^ a b c Davis, Matthew P.; Fielitz, Christopher (2010-12-01). "Estimating divergence times of lizardfishes and their allies (Euteleostei: Aulopiformes) and the timing of deep-sea adaptations". Molecular Phylogenetics and Evolution. 57 (3): 1194–1208. Bibcode:2010MolPE..57.1194D. doi:10.1016/j.ympev.2010.09.003. ISSN 1055-7903. PMID 20854916.
- ^ Woodhouse (1910)
- ^ Glare (1982)
- ^ a b FishBase (2000)
- ^ Scharpf, Christopher. "Table of Contents". etyfish.org. Retrieved 9 May 2025.
- ^ a b c Nelson (2006, p. 214)
- ^ a b Johnson & Eschmeyer (1998)
- ^ Chida, Mori (Fall 2022). "A new species of dercetid and the assessment of the phylogeny of the Enchodontoidei (Teleostei: Aulopiformes)". ERA. doi:10.7939/r3-nqmz-nf15. Retrieved 2023-12-28.
- ^ Alvarado-Ortega, Jesús; Díaz-Cruz, Jesús Alberto (2021-01-01). "Hastichthys totonacus sp. nov., a North American Turonian dercetid fish (Teleostei, Aulopiformes) from the Huehuetla quarry, Puebla, Mexico". Journal of South American Earth Sciences. 105 102900. Bibcode:2021JSAES.10502900A. doi:10.1016/j.jsames.2020.102900. ISSN 0895-9811.
- ^ "Stratigraphy and Paleobiology of the Upper Cretaceous-Lower Paleogene Sediments from the Trans-Saharan Seaway in Mali". MorphoBank datasets. 2019-07-01. doi:10.7934/p2735. S2CID 242354960.
- ^ Diogo (2008)
- ^ Taylor (2009)
- ^ Uyeno, Teruya. "A Miocene alepisauroid fish of a new family, Polymerichthyidae, from Japan." Bull. Nat. Sci. Mus 10 (1967): 383–394.
- ^ Dietze, Kathrin (2009-06-01). "Morphology and phylogenetic relationships of certain neoteleostean fishes from the Upper Cretaceous of Sendenhorst, Germany". Cretaceous Research. 30 (3): 559–574. Bibcode:2009CrRes..30..559D. doi:10.1016/j.cretres.2008.11.001. ISSN 0195-6671.
- ^ Beckett, Hermione; Giles, Sam; Friedman, Matt (2018-11-14). "Comparative anatomy of the gill skeleton of fossil Aulopiformes (Teleostei: Eurypterygii)". Journal of Systematic Palaeontology. 16 (14): 1221–1245. Bibcode:2018JSPal..16.1221B. doi:10.1080/14772019.2017.1387184. ISSN 1477-2019.
References
[edit]- Diogo, Rui (2008). "On the cephalic and pectoral girdle muscles of the deep sea fish Alepocephalus rostratus, with comments on the functional morphology and phylogenetic relationships of the Alepocephaloidei (Teleostei)". Anim. Biol. 58 (1): 23–29. doi:10.1163/157075608X303636.
- Froese, Rainer; Pauly, Daniel (eds.). "Order Aulopiformes". FishBase.
- Glare, P.G.W., ed. (1982). "forma". Oxford Latin Dictionary (1st ed.). Oxford: Oxford University Press. ISBN 0-19-864224-5.
- Johnson, R.K.; Eschmeyer, W.N. (1998). "Aulopiformes". In Paxton, J.R.; Eschmeyer, W.N. (eds.). Encyclopedia of Fishes. San Diego: Academic Press. pp. 123–126. ISBN 0-12-547665-5.
- Nelson, Joseph S. (2006). Fishes of the World (4th ed.). John Wiley & Sons, Inc. ISBN 0-471-25031-7.
- Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology. 364: 560. Archived from the original on 2011-07-23. Retrieved 2011-05-17.
- Taylor, Christopher (2009-02-05). "Living Larvae and Fossil Fish". Catalogue of Organisms. Retrieved 2009-09-28.
- Woodhouse, S.C. (1910). "Flute". English-Greek Dictionary - A Vocabulary of the Attic Language. Broadway House, Ludgate Hill, E.C.: George Routledge & Sons Ltd. p. 330.
Aulopiformes
View on GrokipediaSystematics and Taxonomy
Historical Perspectives
The taxonomic history of Aulopiformes began in the 19th century with the initial recognition of its constituent families as a distinct group of teleost fishes, primarily through the work of ichthyologist Theodore N. Gill. In his 1893 classification, Gill established the suborder Myctophoidei to encompass families such as Myctophidae, Neoscopelidae, and Aulopidae, while also defining the suborder Synodonti for Synodontidae and Chlorophthalmidae, thereby grouping these taxa based on shared morphological traits like their elongate bodies and predatory adaptations, and placing them near the lanternfishes (Myctophiformes). This early framework highlighted the affinities among these deep-sea and benthic forms but did not yet formalize them as a unified order. By the mid-20th century, advancements in comparative anatomy led to the placement of Aulopiformes within the superorder Cyclosquamata, as proposed by Lev S. Berg in 1940. Berg's classification emphasized shared characteristics such as cycloid scales and the presence of an adipose fin, allying Aulopiformes with other cycloid-scaled teleosts like Myctophiformes and Salmoniformes to reflect their evolutionary convergence in open-water and deep-sea environments.[6] This superordinal grouping persisted in subsequent schemes, providing a broader context for understanding aulopiform diversity amid the era's focus on scale morphology and fin structures as phylogenetic markers. A pivotal refinement occurred in 1966 with the seminal work of Greenwood et al., who, in their provisional classification of living teleostean fishes, elevated Aulopiformes to ordinal status within Cyclosquamata and introduced early subordinal divisions. They delineated the suborder Synodontoidei (including Synodontidae and Aulopidae) and Chlorophthalmoidei (encompassing Chlorophthalmidae and Bathysauridae), based on differences in jaw mechanics, eye structure, and body elongation, thereby establishing a more structured framework that integrated fossil and extant forms from the "Fishes of the World" tradition. Further evidence for the monophyly of Aulopiformes emerged from Rosen and Patterson's 1969 study on gill arch morphology, which identified unique synapomorphies in the upper pharyngeal elements, such as the modified second pharyngobranchial and uncinate process, distinguishing aulopiforms from neighboring groups like Myctophiformes. This anatomical analysis solidified Aulopiformes as a cohesive order by demonstrating shared derived traits in their suspensorium and branchial skeleton, influencing late-20th-century classifications up to the 1990s.[7]Current Classification
Aulopiformes comprises approximately 16 extant families, around 50 genera, and over 300 species of primarily marine ray-finned fishes, with recent catalogs as of November 2025 listing about 300 valid species.[1] The order is divided into several suborders, including the extant Alepisauroidei (encompassing families like Alepisauridae, known for lancetfishes), Giganturoidei (including Bathysauridae and Giganturidae), and Synodontoidei (such as Synodontidae and Chlorophthalmidae), alongside the extinct suborder Enchodontoidei.[3] These suborders reflect morphological and ecological groupings, with Alepisauroidei representing the most species-rich radiation at around 173 species.[8] The family-level taxonomy includes a mix of benthic, pelagic, and bathypelagic groups, with species counts varying widely. For instance, Synodontidae (lizardfishes) contains about 81 species across genera like Synodus and Saurida, primarily in shallow coastal waters.[9] Paralepididae (barracudinas) is another diverse family with roughly 72 species in genera such as Paralepis and Lestidium. Smaller families like Aulopidae (flagfins) have around 16 species in four genera, including Aulopus. The following table summarizes key families with approximate extant species counts based on recent catalogs as of November 2025:| Family | Common Name | Approximate Species Count | Representative Genera |
|---|---|---|---|
| Synodontidae | Lizardfishes | 81 | Synodus, Saurida |
| Paralepididae | Barracudinas | 72 | Paralepis, Stemonosudis |
| Alepisauridae | Lancetfishes | 2 | Alepisaurus |
| Chlorophthalmidae | Greeneyes | 22 | Chlorophthalmus |
| Evermannellidae | Sabertooth fishes | 8 | Evermannella, Coccorella |
| Scopelarchidae | Pearleyes | 18 | Scopelarchus, Benthalbella |
| Aulopidae | Flagfins | 16 | Aulopus, Procerauropsis |
| Giganturidae | Whalefishes | 2 | Gigantura |
| Bathysauridae | Deep-sea lizardfishes | 2 | Bathysaurus |
| Others (e.g., Ipnopidae, Omosudidae) | Various deep-sea forms | <10 each | Ipnops, Omosudis |
