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Original Articles
1.
Introduction
Listracanthus Newberry & Worthen, 1870 is a 'form' taxon representing an enigmatic chondrichthyan known only from its mostly small but elaborate spines and a few dermal denticles (ichthyoliths). It ostensibly ranges from the Carboniferous to the Triassic (Mutter & Neuman, 2006) and was first described from Carboniferous strata in Illinois, USA (Newberry & Worthen, 1870). Elsewhere in the United States it has been reported from Ohio, Indiana, Missouri and Kansas (Newberry, 1873, 1875; Newberry & Worthen 1870; Hibbard, 1938; Chorn & Reavis, 1978; Schultze et al. 1982; Hamm & Cicimurri, 2005), while in Europe the genus has been reported from the Carboniferous of England (Stobbs, 1905; Edwards & Stubblefield, 1948), Scotland (Woodward, 1891, p. 149), Belgium (Woodward, 1891; Koninck, 1878; Derycke et al. 1995), Germany (Bolton, 1896; Schmidt, 1950) and the Czech Republic (Lang, 1979; Stamberg & Lang, 1979). In Asia Listracanthus has been reported from the Carboniferous of northern China (Lu et al. 2002, 2005) and also from the Permian of the Ural region of Russia (Ivanov, 2005). Turner (1993) reported Listracanthus in the Carboniferous of Queensland, Australia (the first occurrence in the southern Hemisphere) on the basis of a single spine, but several dermal denticles figured by her as 'hybodontid' also resemble those of Listracanthus. Listracanthus has also been considered present in the Triassic of Canada where its occurrence has been considered a part of the so-called Lilliputian recovery fauna after the Permian mass extinction event (Mutter & Neuman, 2009). Although enigmatic, Listracanthus was considered by Patterson (1965) to be a junior synonym of the holocephalan Deltoptychius, but recent workers accept that Listracanthus represents an early, although somewhat unusual, elasmobranch (e.g. Mutter & Neuman, 2006). Here we describe a new specimen of elasmobranch with associated spines and denticles that resembles Listracanthus but displays a wide variety of dermal denticle morphotypes as well as several significant differences in spine structure from the holotype of Listracanthus.
Institutional abbreviations. UALVP - Laboratory for Vertebrate Paleontology - University of Alberta - Edmonton - Canada; YPM - Yale Peabody Museum - USA; NHMUK - Natural History Museum - London.
2.
Locality
Material examined in this study was collected by one of...