ABSTRACT

The interrelationships of the gonorynchiform fishes, including fossil and Recent genera, are revised and updated. A historic summary of the different hypotheses of their phylogenetic relationships is presented. The morphological disparity of the Gonorynchiformes, as known today, prevented its two longest-known genera, Chanos and Gonorynchus, from being gathered into the same order until 1960, although their kinship had already been proposed in 1846. Discoveries of more Recent forms, and of their impressive fossil record, have added both abundant data and new challenges to the study of their phylogenetic relationships.

In addition to the historic outline, we present herein a new, entirely revised cladistic analysis of the Gonorynchiformes, including a total of 24 nominal fossil and Recent genera. Only seven of the gonorynchiform genera are living taxa, evidencing that this is a group with a diverse fossil record. The fossil record of the Gonorynchiformes, as an ensemble, is quite geographically widespread for such a small group, extending to Europe, North and South America, Africa, Australia, and Asia; it dates back to the Early Cretaceous, so that gonorynchiforms may be considered a relict or “living fossil” group.

228Previous evidence indicates that the Gonorynchiformes are sister group to the Otophysi, (i.e., fishes with a functioning Weberian apparatus), together forming the clade Ostariophysi. The results of the present analysis, consisting of 130 revised characters, including osteological and myological ones, confirm that the Gonorynchiformes comprise a monophyletic group that consists of two monophyletic, sister-group suborders, the Chanoidei and the Gonorynchoidei. The relationships of the three families {Chanidae + [Gonorynchidae + Kneriidae]} are confirmed. Each family has at least one Recent genus, and the Kneriidae have no known fossil record.

An evaluation of the evolutionary history of the Gonorynchiformes and a systematic revision are also provided in this chapter. Future research on this group should include an evaluation of some problematic taxa, mostly †Dastilbe and the Middle Eastern fossil gonorynchids. A separate approach to the interrelationships of the Chanoidei and the Gonorynchoidei, the latter including molecular studies, may help unravel further elements of phylogenetic uncertainty.