Lungfishes, tetrapods, paleontology, and plesiomorphy. Bulletin of the AMNH ; v. 167, article 4

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New York : American Museum of Natural History
"We conclude that the internal (excurrent) nostril of Recent lungfishes is a true choana, as judged by its comparison with (1) the internal nostril of a Devonian lungfish species which opens through the bony palate internal to an arcade of maxillary and premaxillary teeth; (2) the choana of the Devonian ichthyostegid amphibians, and (3) nostril development in Recent urodeles. The idea that lungfishes might therefore be the sister group of tetrapods is compared with the competing, deeply entrenched theory that rhipidistian fishes and eusthenopterids in particular include the ancestor of tetrapods. Our own theory, derived from study of Recent and fossil material, and an analysis of literature spanning 140 years, is framed in the context of a classification of the main groups of fossil and living gnathostomes: acanthodians, chondrichthyans, cladistians, actinopterygians, rhipidistians, actinistians, dipnoans, and tetrapods. In formulating our proposal we have reviewed the anatomy of the nasal capsule, nostrils and related structures, paired fins and their girdles, dermal bones of the skull, palate and jaw suspension, hyoid and gill arches, ribs and vertebrae, and scale and tooth structure. We hypothesize, in agreement with most nineteenth- and many twentieth-century biologists, and in disagreement with the current paleontological view, that lungfishes are the sister group of tetrapods, and further that actinistians are the sister group of those two, and that Eusthenopteron is the sister group of those three. We also conclude that the characters used formerly to link Eusthenopteron with tetrapods either (1) are primitive for all bony fishes (including cladistians and actinopterygians) or for living gnathostomes (including chondrichthyans); (2) are convergent with those of several groups of gnathostomes; (3) only justify the inclusion of Eusthenopteron in a group with actinistians, dipnoans and tetrapods; or (4) are spurious. We attribute the century of confusion about the structure and position of lungfishes to the traditional paleontological preoccupation with the search for ancestors, to the interpretation of Eusthenopteron in the light of tetrapods and the reciprocal interpretation of fossil amphibians in the light of Eusthenopteron, and to the paleontological predilection for using plesiomorphous characters to formulate schemes of relationships"--P. 163.
p. 163-275 : ill. ; 26 cm.
Includes bibliographical references (p. 264-275).