A detailed redescription of Santanichthys diasii is presented, based on several new acidprepared and very well-preserved specimens. S. diasii has a complete Weberian apparatus and is at present the earliest otophysan fish known (early Cretaceous, Albian). In addition, this fish displays at least one synapomorphy of modern characiforms (large and globular lagenar capsules that extend well lateral to the cranium) and we consequently suggest that it is a stem characiform. If this is correct, it represents a significant temporal extension for characiforms. We discuss the phylogenetic implications of its unique combination of features in light of earlier phylogenetic hypotheses.
ABSTRACT. The genus Spaniodon is decribed in detail. Contrary to previous authors, we have only recognized two species, S. elongatus and S. latus. Spaniodon shows the synapomorphies of clupeocephalans, protacanthopterygians and salmoniforms. Its relationships among salmoniforms are still undecided, although it could be closely related to the Osmeroidei. The main character that supports this grouping is the dermal part of the mesethmoid formed by the partial fusion of a pair of lateral dermethmoids, whereas the rostral is absent. These conclusions are also supported by a global phylogenetic study of the teleosts.
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