Evolution, paleontology, and classification

inatheriniform

Also known as: Atheriniformes

Written by Colin Patterson

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Related Topics:: killifish; live-bearer; silversides; saury; Exocoetoidei

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Paleontology

The four orders Beryciformes, Zeiformes, Lampridiformes, and Atheriniformes are primitive groups within the superorder Acanthopterygii. The Beryciformes and Zeiformes apparently form a related group, originating in the Cretaceous, its closest relatives being the Perciformes. The Lampridiformes also originated in the Cretaceous and are of uncertain relationships, being to some extent intermediate between the Acanthopterygii and Paracanthopterygii. The Atheriniformes represent a radiation from near the base of the acanthopterygian stock, but their exact relationships within this group are not known. The present distribution of atheriniforms indicates that the group arose in fresh or brackish waters of the tropical Indo-Pacific region, but little is known of their early fossil history.

Annotated classification

Order Beryciformes
Spiny-rayed fishes with a pelvic spine, an orbitosphenoid, and 19 principal rays in the tail. Of the two main lineages the first contains the Holocentridae, coastal fishes of warm seas. The second is a series of oceanic families centring around the Trachichthyidae. Both groups have fossil records back to the Cretaceous, the 2 lines converging in the Middle Cretaceous.
- - Family Holocentridae (soldierfishes and squirrelfishes)
    Circumtropical, with partly separate spinous dorsal fin. Several extinct genera, Middle Cretaceous onward.
  - Family Monocentridae (pinecone fishes)
    Armoured, very spiny. Teeth on endopterygoid bone. Two genera; Indo-Pacific.
  - Family Trachichthyidae
    Midwater (mesopelagic) or deepwater pelagic fishes, worldwide. Skull bones cavernous, with large mucus cavities. Several extinct genera, Middle Cretaceous onward.
  - Family Berycidae (alfonsinos)
    Upper and midwaters in open ocean; worldwide. Pelvic girdle enlarged and tightly joined with the pectoral.
  - Family Anoplogasteridae
    Deep-sea, adults with large fangs; 1 genus.
  - Family Diretmidae
    Very deep bodied, compressed fishes; 1 genus.
  - Family Anomalopidae (lantern-eyed fishes)
    With subocular luminous organ, found near the surface at night; 2 Indo-Pacific genera, 1 Atlantic.
  - Family Stephanoberycidae (prickle fishes)
    Scales and head spiny, fin spines reduced; bathypelagic, worldwide; 3 genera.
  - Family Melamphaeidae (big-scale fishes)
    Abundant deepwater open ocean fishes, worldwide; softbodied and black. Fossils in the Miocene.
  - Family Gibberichthyidae
    Like Melamphaeidae but with stronger fin spines. Atlantic, 1 or 2 genera.
  - Family Rondeletiidae (whale fishes)
    Head large, no scales, fin spines, or swim bladder; bathypelagic, 1 genus.
  - Family Cetomimidae (whale fishes)
    Mouth huge, spineless fins, bathypelagic, worldwide.
  - Family Barbourisiidae (whale fishes)
    No fin spines, scales reduced to minute spines, red, bathypelagic, 1 genus.
Order Zeiformes
Like Perciformes but with up to 9 pelvic rays and only 12–13 principal caudal rays.
- - Family Caproidae (boar fishes)
    Most primitive family, 21–23 vertebrae, fossils in the Oligocene; 2 genera, worldwide.
  - Family Zeidae (John Dories)
    Deep bodied and laterally flattened. Mouth large; scales reduced; more than 30 vertebrae. Several genera, worldwide; fossils in the Eocene.
  - Family Grammicolepididae
    Mouth very small, scales drawn out into oblique bands. Two genera, mesopelagic.
  - Family Oreosomatidae
    Larva covered with large tubercles. Four genera, benthic (bottom dwelling); worldwide.
  - Families Zeniontidae and Macrurocyttidae
    Two small families, the first with two genera, the second with one, too poorly known to be characterized.
Order Lampridiformes
Similar to Beryciformes, but with no pelvic spine; upper hypural bones fused with their supporting centrum.
- Suborder Lampridoidei
  Deep-bodied forms.
  - Family Veliferidae
    One living genus (Velifer) with saillike fins, 33 vertebrae. Fossils from Paleocene and Eocene, several extinct genera.
  - †Families Aipichthyidae and Pharmacichthyidae
    Extinct families, each containing a single Upper Cretaceous genus; appear to be primitive lampridiforms, resembling Velifer in deep trunk, but with fewer vertebrae and more primitive tail skeletons.
  - Family Lamprididae (opahs)
    One genus (Lampris); 15–17 pelvic rays, 46 vertebrae. Fossils from Miocene. Length to 2 m (61/2 ft), weight to 140 kg (over 300 lb); surface waters (epipelagic) of warm seas; widespread.
- Suborder Trachipteroidei
  Ribbonlike, about 100 vertebrae.
  - Family Trachipteridae (dealfishes)
    Pelvic fins with 5–9 rays, no anal fin, jaws toothed. Length to 1.2 m (4 ft); epipelagic. Worldwide in warm seas.
  - Family Lophotidae (unicorn fishes)
    Scales lacking; pelvic fins small or absent, anal fin short. Fossils from Oligocene. Worldwide in warm seas.
  - Family Regalecidae (oarfishes)
    Anal fin lacking; 1 pelvic ray elongated; jaws toothless; length to 9 m (30 ft); weight to 300 kg (660 lb). Mesopelagic, tropical.
- Suborder Stylephoroidei
  - Family Stylephoridae
    Deep-sea forms with enlarged telescopic eyes, about 50 vertebrae, 2 filamentous caudal rays. Known from only a few specimens.
- Suborder Ateleopoidei
  - Family Ateleopidae
    Specialized, deep-sea, bottom-living fishes, Indo-Pacific and Atlantic, usually placed among the primitive teleosts, but probably lampridiform.
- Suborder Mirapinnoidei
  - Families Mirapinnidae and Eutaeniophoridae
    Three species of little-known mesopelagic fishes, usually placed as a distinct order of lower teleosts (Mirapinniformes), but probably larval lampridiforms.
- Suborder Megalomycteroidei
  - Family Megalomycteridae
    Four rare, little-known, deep-sea genera, probably larval lampridiforms.
Order Atheriniformes
Premaxilla greatly expanded between maxilla and mandible, without crossed ligaments controlling the upper jaw, infraorbital bone series incomplete.
- Suborder Exocoetoidei
  Lateral line complete and low on the flank in marine forms, the lower pharyngeal bones are fused, no parietals, 9–15 branchiostegals. Found worldwide, but especially abundant in the Indo-Pacific.
  - Family Exocoetidae (halfbeaks and flying fishes)
    Lower jaw often extended; snout not modified. Surface marine waters and freshwaters, worldwide; length to 45 cm (18 in.). Fossil half-beaks in the middle Eocene.
  - Family Belonidae (garfishes and needlefishes)
    Snout bones sutured together, both jaws elongated into a strongly toothed beak. Mostly temperate and tropical marine; a few freshwater; length to 120 cm (almost 48 in.). Fossils in the Oligocene.
  - Family Scomberesocidae (sauries, skippers)
    Snout and jaws as in Belonidae but feebly toothed; small finlets behind dorsal and anal fins. Inshore temperate and tropical marine waters; length to 35 cm (almost 14 in.). Fossils in the Miocene.
- Suborder Cyprinodontoidei
  Lateral line represented by pits on the flank, 4–7 branchiostegal bones. Families mostly distinguished by reproductive specializations.
  - Family Oryziatidae (medakas)
    Most primitive cyprinodonts; a single genus in freshwaters and brackish waters in Indonesia.
  - Family Adrianichthyidae
    Mouth and snout enlarged and shovellike. Two genera in lakes in Celebes; length 7–20 cm (23/4 to almost 8 in.). Fossils in Late Tertiary in Celebes.
  - Family Horaichthyidae
    Small fishes with anal fin modified, in males, for clasping female in mating. One genus, freshwater, India.
  - Family Cyprinodontidae (killifishes or egg-laying topminnows)
    Circumtropical and temperate marine and freshwater, many genera. Many popular aquarium fishes; length to 15 cm (6 in.). Fossils in the Oligocene.
  - Family Goodeidae (Mexican topminnows)
    Live-bearing, but male lacks elaborate intromittent organ found in poeciliids. About 10 genera, in rivers draining the Mexican Plateau; length to about 10 cm (4 in.).
  - Family Jenynsiidae
    Small fishes with asymmetrical genital organs; 1 genus; rivers of South America.
  - Family Anablepidae (four-eyed fishes)
    Characterized by specialized eye structure (see above Form and function); 1 genus, 2 species; surface waters in rivers and estuaries of South America.
  - Family Poeciliidae (live bearers or viviparous topminnows)
    Native to tropical and subtropical America but introduced elsewhere for mosquito control. Freshwaters and coastal marine waters. Length 1.5 to about 15 cm (over 1/2 to 6 in.). Family includes mollies (Mollienesia), guppies (Lebistes), swordtails (Xiphophorus), and many other popular aquarium fishes, as well as the mosquito fishes (Gambusia).
- Suborder Atherinoidei
  Lateral line variable; 5–7 branchiostegal bones; separate spinous dorsal fin.
  - Family Melanotaeniidae
    Many species; freshwater bodies of New Guinea and Australia. Compressed, deep-bodied; pointed snout; 5–20 cm (2 to 8 in.).
  - Family Atherinidae (silversides)
    Lateral line absent; pelvic fins midway along belly; length 7–70 cm (23/4 to 271/2 in.). Coastal and freshwater, worldwide in warmer regions. Many genera. Fossils from middle Eocene.
  - Family Isonidae
    Pectoral fins unusually high on body. Small marine fishes; Indian and Pacific Oceans. Two genera.
  - Families Phallostethidae and Neostethidae
    Males with priapium, an organ derived from pectoral and pelvic girdles, functioning to clasp the female. Tiny fishes (3–5 cm [1 to 2 in.] long); confined to freshwaters and brackish waters in Thailand, Indonesia, and the Philippines.