2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 17
Presentation Time: 8:00 AM-12:00 PM


FEARNHEAD, Fiona E., School of Earth Sciences, Birkbeck College, University of London, Malet Street, Bloomsbury, London, WC1E 7HX, England and DONOVAN, Stephen K., Department of Palaeontology, National Natuurhistorisch Museum, Darwinweg 2, Postbus 9517, Leiden, NL-2300 RA, Fiona.Fearnhead@barnet.ac.uk

The crinoids of the Llandovery (Early Silurian), that is following the end Ordovician mass extinction but before their great diverstiy peak in the Wenlock (Middle Silurian), remain poorly known. They are best known from North America (e.g. Brassfield Formation of the Midwest U.S.A. and Anticosti Island, Arctic Canada) and the British Isles. The only comprehensive, systematic account of the British Llandovery Crinoidea formed part of the (unpublished) Ph.D thesis of W.H.Ramsbottom (University of London, 1954). In over 50 years since Ramsbottom's work, many of ‘his' taxa have been published and revised, and new species have been described from the Llandovery of the British Isles.

However, three of Ramsbottom's species still await formal description. The monobathrid camerate Hapalocrinus sp. nov., a unique, near-complete specimen from the Damery Beds of the Tortworth Inlier of the Welsh borderlands (Telychian, griestoniensis Biozone), is a fine example of a genus better known from the Devonian. The diplobathrid camerate Dimerocrinites sp. nov. from the Newlands Formation, Craighead Inlier of the Girvan district, southwest Scotland (Aeronian, triangulatus Biozone) represents a genus well-known from the slightly younger Much Wenlock Limestone Formation of England. The cladid Petalocrinus sp. nov., from the Petalocrinus Limestone of the Woolhope Inlier of the Welsh borderland (upper Telychian or lower Wenlock) is so common that it forms a mappable horizon (Pocock, 1930, Q. Jl geol. Soc. Lond., v. 86, p. 50-63). In addition, the senior author has collected a new, articulated species from the Gasworks Mudstone Formation of Haverfordwest, South Wales (Rhuddanian?), indicating that the British Llandovery still contains new and exciting crinoids that await discovery.