Diatom phylogeny: Fossils, molecules and the extinction of evidence

Diatom phylogeny is progressing, thanks largely to the use of molecular data in determining relationships. Although these data are now accumulating at great speed and quantity, relationships among diatom higher taxa have become anything but clear. While progress in molecular systematics is still possible, significant taxa for determining higher-level relationships reside among groups with high levels of extinction. It is therefore a priority to examine fossil taxa and determine morphological synapomorphies as a test (or point of focus) for any further molecular studies.