Palaeos:		Craniiformea
Brachiopoda		Craniida

Order Craniida

(Early Ordovician - Recent)

The Craniida is a very low diversity group of brachipopods including only the single Superfamily Cranioidea Menke, 1828 and family Craniidae Menke 1828

The following extant and fossil genera are among those included: Ancistrocrania, Crania, Craniscus (extant), Danocrania, Isocrania, Neoancistrocrania (extant), Novocrania (extant), and Valdiviathyris (extant). Valdiviathyris and Neoancistrocrania were sometimes separated in a family Valdiviathyrididae although the tendency now is to include them all in a single family

Most Craniidae are long-extinct forms known only from fossils like all other Craniforma. However, some 20 species of this 470-million-year-old lineage are extant today. They include Valdiviathyris quenstedti which has remained essentially unchanged for the last 35 million years. Present-day Valdiviathyris are all but inseparable from those of the Late Eocene and the genus cannot even be divided into chronospecies. Thus, V. quenstedti is a true living fossil and one of the oldest and most long-lived species known to science. Some minimal evolution would obviously have taken place in the meantime, but this would have been essentially silent mutations and marginal adaptations to cooler habitat. - Wikipedia

References

Robinson, Jeffrey H. & Lee, Daphne E. (2007): The Recent and Paleogene craniid brachiopod, Valdiviathyris quenstedti Helmcke, 1940. Systematics and Biodiversity 5(1): 123–131. doi:10.1017/S1477200006002179 (HTML abstract)

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