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The Coelacanths (derived from Coelacanthiformes, and named after the Carboniferous genus Coelacanthus) are today represented by a single genus, Latimeria, living in deep water off the coasts of Madagascar and Indonesia and elsewhere.
 Evolutionary history
Coelacanths first appear in the mid Devonian and diverged into many different types in the late Paleozoic, reaching their peak in the Triassic. Coelacanths are fish and thus are related to the ancestors of tetrapods, though they evolved differently from the rhipidistian fishes. Their ancestry is contested but most experts believe that rhipidistians are the closest relatives of coelacanths. Evidence for this comes largely from the structure of the braincase of the two groups, which are similar.
 Living fossil
The coelacanth is an iconic "living fossil," having been known only from fossils before the first living specimen was discovered. As a group, the coelacanths were very successful from the Devonian until the Cretaceous, with several genera and species described, but the modern genus Latimeria is not known from the fossil record. The earliest known coelacanths are in fact quite different from Latimeria. The last known fossil coealacanths are the late Cretaceous genus Macropoma, which is very similar to Latimeria. No fossils are known from the Cretaceous until the present. The reason for this gap in the fossil record is not known, but suggests that, since the Cretaceous period, coelacanths have either been relatively rare or have inhabited environments not conducive to fossilization.
- Carroll, R. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman & Company, New York.
- Schaeffer, B. 1952. The Triassic coelacanth fish Diplurus, with observations on the evolution of the Coelacanthini. Bulletins of the American Museum of Natural History 99: 25-78.
- Thomson, K. S. 1967. Mechanisms of intracranial kinetics in fossil rhipidistian fishes (Crossopterygii) and their relatives. Zoological Journal of the Linnean Society 46: 223-253.