Brachiopods were the dominant invertebrates of the Palaeozoic seabed, occupying a wide range of benthic niches for some 250 million years. Despite a fairly conservative body plan the phylum evolved a spectacular range of morphologies and life styles from the infaunal lingulides and attached terebratulids and rhynchonellids to the coral-like richthofeniids and extravagantly spiny, recumbent waagenoconchids. Although less abundant and diverse following the end Permian extinction event, the phylum continued to participate in benthic community structures throughout the Mesozoic and Cenozoic and are relatively abundant, albeit locally today. To date some 6,000 genera of brachiopods have been reported. In the last 25 years there have been huge advances in our knowledge of the phylum, not least through the revision of part H of the Treatise on Invertebrate Paleontology (edited by Williams, Alwyn and others, 6 volumes: 2000-2008), the publication of the proceedings of five international brachiopod congresses, the most recent in Copenhagen (edited by Harper, D.A.T., Long, S.L and Nielsen, C., 2008) together with a memorial volume to Sir Alwyn Williams (edited by Cusack, M. and Harper, D.A.T. 2008). Apart from increased knowledge of the anatomy and morphology of the phylum, great leaps forward have been made in understanding its origin, phylogeny and relationship to other groups using both morphological and molecular data. Much new data is available too on the functional morphology of the group, its distribution in time and space and its participation in extinction and radiation events.

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