Spiriferida

Spiriferida is an order of extinct articulate brachiopod fossils which are known for their long hinge-line, which is often the widest part of the shell.

In some genera (e.g. Mucrospirifer) it is greatly elongated, giving them a wing-like appearance.

The feature that gives the spiriferids their name ("spiral-bearers") is the internal support for the lophophore; this brachidium, which is often preserved in fossils, is a thin ribbon of calcite that is typically coiled tightly within the shell.

They increased in diversity throughout the Silurian and underwent a dramatic evolutionary radiation during the Devonian period, reaching peak development in variety and numbers.

Spiriferida survived the great Permian extinction (Albeit at much less diversity), finally becoming extinct during the Early to Middle Jurassic.

A Devonian spiriferid brachiopod from Ohio which served as a host substrate for a colony of hederellids .