Article 20. Genus-group names ending in -ites, -ytes or -ithes given to fossils. A name formed by adding the suffix -ites, -ytes or -ithes to the whole or the stem of an available name of a genus-group taxon, and applied to fossils to distinguish them from extant members of that taxon, without clear evidence of intent to establish a new genus-group taxon, is available only for the purposes of the Principle of Homonymy. Such a name cannot be used as the valid name of a taxon [Art. 23.1] or as the basis of a family-group name [Art. 11.7.1.4].

Example. The generic names Pectinites and Tellinites Schlotheim, 1813, used to denote fossil shells thought to belong to the Recent genera Pecten Müller, 1776 and Tellina Linnaeus, 1758, are available only for the purposes of the Principle of Homonymy. However, names proposed for genus-group taxa of fossils (such as Pentacrinites Blumenbach, 1804) and not merely to indicate fossil members of genera of extant animals are not affected by this Article and may be available.