The postcranial anatomy of two Middle Devonian lungfishes (Osteichthyes, Dipnoi) from Mt. Howitt, Victoria, Australia
Long, John A
Clement, Alice M
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The postcranial skeletons of two upper Givetian lungfi shes from Mt. Howitt, Victoria, Australia, show remarkable similarities, despite the fact that one is a tooth-plated form (Howidipterus Long 1992) whilst the other has a denticulate dentition (Barwickia Long 1992). Both genera show identical body shape with a short fi rst dorsal fi n and greatly elongated second dorsal fi n, and small anal fi n. The cleithra and clavicles are remarkably similar except for Barwickia lacking external ornament on the lateral lamina of the cleithrum and having a smaller branchial lamina on the clavicle. Both have paddle-shaped subdermal anocleithra that meet the posterior process of the I bone, approximately the same numbers of cranial ribs, pleural ribs, supraneural and subhaemal spines, the same expanded dorsal and anal fi n basals with similar number of proximal and middle radials supporting the fi ns, and approximately the same number of radials supporting the hypochordal lobe of the caudal fi n. These numerous similarities in the postcranial skeletons of the two genera strongly suggest that their differing feeding mechanisms probably evolved from a shared ancestral form having a similar postcranial skeleton. Implications for hypotheses of dipnoan phylogeny are discussed. Keywords Pisces, osteichthyes, Dipnomorpha, Devonian, postcranial skeleton, anatomy, evolution, Australia
Copyright 2009 Museum Victoria. Published version of the paper reproduced here with permission from the publisher.