Aulopiformes

Aulopiformes Temporal range: 125–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Cretaceous to present[1]
Variegated lizardfish, Synodus variegatus (Synodontoidei: Synodontidae)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Clade:	Eurypterygii
Superorder:	Cyclosquamata
Order:	Aulopiformes D. E. Rosen, 1973
Type genus
Aulopus Cloquet, 1816
Suborders
Alepisauroidei Chlorophthalmoidei †Enchodontoidei Giganturoidei Synodontoidei
Synonyms
Macristiidae (see text)

Aulopiformes /ˈɔːləpɪfɔːrmiːz/ 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. The scientific name means "Aulopus-shaped", from Aulopus (the type genus) + the standard fish order suffix "-formes". It 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]

They are grouped together because of common features in the structure of their gill arches. Indeed, many authors have considered them so distinct as to warrant separation in a monotypic superorder of the Teleostei, under the name 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 so closely related to some Protacanthopterygii to be included in that superorder. In particular, this group might be the sister taxon of the Salmoniformes (salmon, trout, and relatives). 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.^[5][6]

An extinct clade of Aulopiformes, the suborder Enchodontoidei and its many constituent families, were dominant nektonic fish throughout much of the Late Cretaceous.^[1][7] Several other extant aulopiform families also have Cretaceous representatives, and phylogenetic evidence indicates that the order as a whole diversified into its extant families around the Early Cretaceous, making it rather ancient. These diversifications included the earliest adaptations for deep-sea living, which is common among many extant aulopiform taxa.^[8]