Authors: HERRINGSHAW, LIAM G.¹; THOMAS, ALAN T.²; SMITH, M. PAUL²

Source: Palaeontology, Volume 50, Number 5, September 2007 , pp. 1211-1229(19)

Publisher: Wiley-Blackwell

Abstract:

: 

Although their record extends back to the Early Ordovician, the occurrence of fossil starfish (Echinodermata: Asteroidea) is dependent almost exclusively upon horizons of exceptional preservation. Thus, asteroids found in Silurian obrution deposits of the English Midlands and Welsh Borderlands are particularly significant to an understanding of the early diversity of the group. Six species are described here: Hudsonaster? carectum sp. nov. (Hudsonasteridae), from the lower part of the Lower Elton Formation; and, from the Much Wenlock Limestone Formation, the hudsonasterids Doliaster brachyactis gen. et sp. nov. and Siluraster? ketleyi (Spencer, 1916), the lepidasterids Lepidaster grayi Forbes, 1850 and Lepidactis wenlocki Spencer, 1918, and the palasterinid Palasterina orchilocalia sp. nov. Though few in number, they show a diverse range of body morphologies when compared with Ordovician taxa: L. wenlocki had long, slender rays when fully grown whereas D. brachyactis is the first asteroid with the short-rayed body form of extant cushion stars. Most distinctive of all is L. grayi, the earliest multiradiate taxon known, all complete specimens of which have 13 rays. This morphological variety is interpreted as indicating that by the Early Silurian starfish were exploiting a wide range of feeding habits and ecological niches.

Keywords: Silurian; Wenlock; Asteroidea; starfish; multiradiate; taxonomy; palaeoecology

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1475-4983.2007.00699.x

Affiliations: 1: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT; current address: Department of Geology and Petroleum Geology, Meston Building, King's College, University of Aberdeen, Aberdeen AB24 3 2: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; s: ; m.p.smith@bham.ac.uk, Email: a.t.thomas@bham.ac.uk

Publication date: 2007-09-01

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