lobefin

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lobefin,

common name for any of a group of lunged, fleshy-finned, bony fishesfish,
limbless aquatic vertebrate animal with fins and internal gills. Traditionally the living fish have been divided into three class: the primitive jawless fishes, or Agnatha; the cartilaginous (sharklike) fishes, or Chondrichthyes; and the bony fishes, or Osteichthyes.
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, also called crossopterygians, that were dominant in the Devonian period and may have given rise to amphibiansamphibian,
in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the caecilians, or limbless amphibians (order
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. They had heavy, ungainly bodies and stumpy paired fins, which may have been the precursors of the limbs of four-footed animals. Known from their fossils, the lobefins were thought to be extinct until 1938, when a live coelacanth was caught in deep water off S Africa. Since then other specimens have been discovered in the Madagascar area. The coelacanths are a marine branch of the lobefins. The coelacanth discovered in 1938, Latimeria chalumne, is a brown to steel-blue fish 5 ft (150 cm) long, with circular, overlapping scales, a laterally flattened three-lobed tail, a spiny dorsal fin, and a vestigial lung. The fish give birth to live young. In 1998 a closely related coelacanth, L. menadoensis, was discovered in Indonesia. The coelacanths and lungfishlungfish,
common name for any of a group of fish belonging to the families Ceratodontidae, Lepidosirenidae, and Protopteridae, found in the rivers of Australia, South America, and Africa, respectively.
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 are more closely related to amphibians, reptiles, and other tetrapods than to other living fish. Lobefins are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Poecilia reticulata, order Coelacanthiformes.

Bibliography

See S. Weinberg, A Fish Caught in Time (2000).

References in periodicals archive ?
Though he has no criticism of the actual study of African lungfish and what they do, he disputes the paper's claim that some of the fossil tracks traditionally attributed to early tetrapods might have been generated by lobe-finned fish learning how to stroll.
The indistinct tracks could be impressions made in soft sediments by lobe-finned fish, he notes.
Previous analyses of fragmentary fossils of Panderichthys, a lobe-finned fish that lived about 385 million years ago, hinted that the creature didn't have bones analogous to those in human wrists and digits.
The 54-kilogram creature was a lobe-finned fish called a coelacanth.
The well-preserved remains of Tiktaalik go a long way, but not quite the whole way, toward filling the gap in the fossil record between the earliest tetrapods and the lobe-finned fish that preceded them, says Clack.
From these lobe-finned fish then arose the earliest members of the tetrapods, or vertebrates with four true limbs.