Asterozoans from the Ludlow Series (upper Silurian) of Leintwardine, Herefordshire, UK

Abstract

A diverse, upper Silurian asterozoan fauna of 16 species is described from Leintwardine, Herefordshire. The asterozoans, comprising taxa assigned to the Asteroidea and Ophiuroidea are found within the Lower Leintwardine Formation of lower Ludfordian (upper Ludlow) age, predominantly in rocks interpreted as submarine channel deposits. This paper amplifies and revises Spencer's treatment of the fauna within the broader context of British Palaeozoic Asterozoa in the early twentieth century. Owing to the rarity of asterozoan‐bearing deposits in the Palaeozoic and particularly the Silurian, the Leintwardine fauna is significant for understanding the early diversity of the group, and assessing potential diversification trends. The study is based on extensive museum collections and material collected from the Church Hill starfish beds. New observations are made on previously known taxa: the asteroids Hudsonaster? leintwardensis (Salter) (which is reassigned), Coccaster bulbiferus Spencer, Urasterella cf. ruthveni (Forbes) and Palasterina cf. antiqua, the stenurids Rhopalocoma pyrotechnica Salter, Sturtzaster marstoni (Salter), Sturtzaster colvini (Salter), Bdellacoma vermiformis Salter and Antiquaster magrumi Kesling, and the oegophiurid ophiuroids Lapworthura miltoni (Salter) and Furcaster leptosoma (Salter). The asteroids Doliaster sp. and Palasterina sp. are recognized. New species are the stenurids Bdellacoma fortispina sp. nov. and Antiquaster apertisulcus sp. nov., and the oegophiurid Loriolaster fragilicalceus sp. nov., the latter extending the range of the genus to the Ludlovian. Morphological and taxonomic diversity of this fauna is high, compared to the preceding Silurian (with the stenurids comprising a notably diverse component of the fauna), supporting potential asterozoan diversification during the Wenlockian to Ludlovian.

Three-dimensional visualization as a tool for interpreting locomotion strategies in ophiuroids from the Devonian Hunsrück Slate

“…In the following descriptions of the specimens scanned, we have adopted the terminology used by the authors in [ 32 ] and [ 48 ].…”

“…[39, fig. 81]) unencumbered by disc tissue are consistent with musculoskeletally-driven motion as is the arm morphology. Gladwell [48] considered that the flexible arms of the Silurian species Furcaster leptosoma suggest high mobility and that the large tube feet may have aided in locomotion as well as feeding.…”

Arceoaster hintei n. gen. n. sp., a late Silurian homeomorphic asteroid (Echinodermata, Hudsonasteridae)

“…Fundamental treatments of the family include Spencer (1914) and Schuchert (1915); Spencer (1916) added to the generic listing of the Hudsonasteridae and accepted nearly all of Schuchert's diagnosis. Herringshaw et al (2007) provided a valuable review of the family and that contribution together with perspectives of Shackleton (2005) and Gladwell (2018) were important to interpretations of Blake (2018), and retained here.…”

“…Herringshaw et al (2007, p. 1216) expressed ‘some uncertainty’ as to familial assignment, but emphasized body wall ossicular configuration; like Arceoaster n. gen., arm shape favors a hadrosidan assignment. Late Silurian Coccaster Spencer, 1916, differs from Arceoaster n. gen. in presence of more elongate arms with angular interbrachial angles, presence of much-enlarged primary radials, and presence of enlarged axillaries that edge the disk margin (Gladwell, 2018, p. 8). Late Ordovician Girvanaster Spencer, 1916, has much-enlarged first superomarginals with centrally directed projections and much-enlarged axillary ossicles (Spencer and Wright, 1966; Shackleton, 2005).…”

“…The monograph of Spencer (1914–1940) with the index of Owen (1965) provide starting background for evaluation of Paleozoic asteroids, with Schuchert (1915), Kesling (1962, 1969), Shackleton (2005), and Blake (2018) contributing later perspectives; Herringshaw et al (2007) and Gladwell (2018) provided important studies of the Hudsonasteridae.…”