Conchodontus, Mitrellataxis and Fungulodus: Conodonts, fish or both?

Conchodontus, Mitrellataxis and Fungulodus are phosphatic microfossils from the Late Devonian of China and North America, alternatively interpreted as conodont elements or fish scales. The histology and microornament of these sclerites have been studied in an attempt to resolve their affinity, and t o determine characters for distinguishing between conodont elements and the ichthyoliths of other lower vertebrates. The histology of all three genera is directly comparable to conodont elements, dispelling the notion that co nodonts are histologically indistinguishable from the teeth and scales of o ther vertebrates. Microornament is found not to be useful in discriminating between high-level taxonomic groupings. White matter and thickness of pris mless enamel are suggested as apomorphies of the Conodonta.