Observations on the ontogeny and homology of the pterygoid bones in Corydoras paleatus and some other catfishes

There has been much uncertainty in the past concerning the identity of the pterygoid bones in Siluroidei (catfishes). This confusion stems from the often increased number of pterygoid elements and their modified development, as compared with other teleosts. The ontogeny of the hyomandibula-pterygoquadrate series in a 20-day developmental sequence of Corydoras paleatus (Jenyns, 1842) embryos is described and supplemented with observations on a clariid and an ageniosid. A historical résumé of previous interpretations of siluroid pterygoid bone homologies is given together with our own which regards the metapterygoid as the central, densely ossified area of the pterygoquadrate, surrounded by the membranodermal ento- and ectopterygoids.