Family LEPISOSTEIDAE (62)—gars. Freshwater, occasionally brackish, very rarely in marine water; eastern North America, Central America (south to Costa Rica), and Cuba.
Body and jaws elongate; mouth with needlelike teeth; abbreviated heterocer-cal tail; heavy ganoid scales, about 50-65 along lateral line; dorsal fin far back, with few rays; three branchiostegal rays; interoperculum absent; two or more supratemporal bones on each side; maxilla small and immobile; supramaxilla absent; myodome absent; vomer paired; swim bladder vascularized (thus permitting aerial respiration); vertebrae opisthocoelous (anterior end convex, posterior end concave, as in some reptiles and unlike all other fish except the blenny Andamia).
The heavily armored predaceous gars usually occur in shallow, weedy areas. Maximum length about 3.0 m, attained in Atractosteus spatula..
The northernmost limit is reached by Lepisosteus osseus in southern Quebec; the southernmost limit is reached by A. tropicus in Costa Rica. This is also the only species that ranges to Pacific slope drainages (from southern Mexico to Honduras). Atractosteus tristoechus is known to enter marine water around Cuba and the Isle of Pines.
Two genera, Lepisosteus and Atractosteus, with seven species (e.g., Nelson et al., 2004, which lists six of the seven). Lepisosteus has four species, with about 14-33 small, pear-shaped gill rakers, and Atractosteus has three species, with about 59-81 large, laterally compressed gill rakers. Fossil species (primarily Cretaceous and Eocene) of Lepisosteus are known from North America, South America, Europe, and India (extant species are restricted to North America); fossil species of Atractosteus are known from North America, South America, Europe, and Africa (extant species are restricted to North America, Cuba, and Central America). Many fossil genera, e.g., Masillosteus, Obaichthys, and Oniichthys (e.g., Micklich and Klappert, 2001).
fOrder PYCNODONTIFORMES. Position uncertain. Upper Triassic to Eocene. This group of reef- or lagoon-dwelling fishes lived primarily around the Tethys Sea and its extensions as the Atlantic opened during the Jurassic. Well-known fossil sites such as Monte Bolca in northern Italy and Solnhofen in southern Germany have added many of the specimens. Extensive research on the systematics of this group has been done by J. Ralph Nursall and Francisco J. Poyato-Ariza. Poyato-Ariza and Wenz (2002) presented a cladistic analysis on the interrelationships of the pycnodontiforms and revised systematic paleontology.
The families recognized in recent literature are Gibbodontidae, Gyrodontidae (e.g., Gyrodus,), Mesturidae, Brembodontidae, Pycnodontidae (with several subfamilies such as Nursalliinae and Proscinetinae), Coccodontidae (with Coccodus the only benthic member of the order), Hadrodontidae, and Trewavasiidae (Nursall, 1996, 1999a, b; Kriwet, 1999, 2004b; Poyato-Ariza and Wenz, 2002, 2004).
Order AMIIFORMES (20)—bowfins
Order AMIIFORMES (20)—bowfins
Taxa that belong to or are related to this group, and placed in the Halecomorphi (ranked as subdivision) in the monumental work of Grande and Bemis (1998), include (with rankings of Grande and Bemis, 1998) order Parasemionotiformes (Parasemionotidae—includes Parasemionotus, in above figure, and Watsonulus), Ionoscopiformes (Ionoscopidae, Oshuniidae, and Ophiopsidae), and Amiiformes (Caturidae, Liodesmidae, Sinamiidae, and Amiidae) (for more information see Maisey, 1991; Lambers, 1995; Grande and Bemis, 1998; Arratia, 2004). Most amiids were apparently freshwater, while most non-amiids were marine.
Family AMIIDAE (63)—bowfins. Freshwater; eastern North America.
Caudal fin abbreviate heterocercal; dorsal fin base long, with about 48 rays; large median gular plate and 10-13 branchiostegal rays; swim bladder can function as a lung; no pyloric caeca. Maximum length about 90 cm.
One species, Amia calva. Fossil amiids (e.g., Amia, Amiopsis, Calamopleurus, Cyclurus, Solnhofenamia, and Vidalamia) are known primarily from freshwater deposits from throughout much of the world; the oldest fossils are ofJurassic age (Maisey, 1991; Grande and Bemis, 1998, 1999; Forey and Grande, 1998). Four subfamilies are recognized by Grande and Bemis (1998), and that work should be consulted for its wealth of information on recent advances on both the extant Amia and on the fossil taxa (including advances in biogeography such as the exciting biogeographical history of members of the subfamily Vidalamiinae).
fOrder ASPIDORHYNCHIFORMES. Position uncertain. One family.
Family ASPIDORHYNCHIDAE. Upper Jurassic and Cretaceous.
Body elongate with a long, slender snout; dorsal and anal fins opposite one another and placed posteriorly; interoperculum absent; maxillae free. Appearance superficially like needlefishes. Most were marine. Lengths up to 1 m. Brito (1999) presented strong evidence from the caudal skeleton that these fishes are in fact teleosts.
Three genera, Aspidorhynchus, Belonostomus, and Vinctifer (Maisey, 1991:170-89; Brito, 1999; Arratia, 2004).
fOrder PACHYCORMIFORMES. One family. The pelvic fin appears to be absent in many pachycormids.
Genera include Asthenocormus, Euthynotus, Hypsocormus, Leedsichthys (which reached an exceptionally large size), Orthocormus, Pachycormus, Prosauropsis, and Protosphyraena (e.g., Arratia and Lambers, 1996; Liston, 2004; Arratia, 2004).
Was this article helpful?