86


Journal of Paleontology 90(1):78–91


Barnes, 2002). The striations are more pronounced than those of D. kentuckyensis but are not as regular as D. staurognathoides. It is unlikely that D. staurognathoides occurs in this section, because it does not occur with D. kentuckyensis. These frag- ments are too broken to confidently identify as D. kentuckyensis.


Family Icriodellidae Sweet, 1988 Genus Icriodella Rhodes, 1953


Type species.—Icriodella superba Rhodes, 1953.


Occurrence.—Middle Ordovician to Llandovery (Klapper and Bergström, 1981).


?Icriodella sp. Figure 3.14


Remarks.—Platform elements with two distinct rows of denti- cles and a deeply excavated aboral surface are characteristic of the genus Icriodella (Rhodes, 1953; Klapper and Bergström, 1981). The specimen from Yamaan Us is a P1 element consisting of two rows of elliptical denticles with an asymmetrical cusp connected by thin ridges, and a deeply excavated base, which conforms to genus Icriodella.


Family Panderodontidae Lindstrӧm, 1970 Genus Panderodus Ethington, 1959


Type species.—Paltodus unicostatus Branson and Mehl, 1933a.


Panderodus serratus Rexroad, 1967 Figure 3.10


1997 Panderodus serratus; Jeppsson, p. 107, fig. 7.4. 2002 Panderodus serratus; Aldridge, pl. 4, fig. 18. 2002 Panderodus serratus; Loydell et al., fig. 4g, h, k. 2006 Panderodus serratus; Valentine et al., p. 230, fig. 11c, d. 2010 Panderodus serratus;Wang and Aldridge, pl. 5, figs. 18–32. ?2013 Panderodus serratus; Jarochowska et al., fig. 2.18.


1988 Panderodus serratus; Nowlan et al., p. 23, pl. 8, figs. 5–7 (see for synonymy).


1967 Panderodus unicostatus serratus Rexroad, p. 47, pl. 4, figs. 3, 4.


Holotype.—Panderodus unicostatus serratus, Indiana Uni- versity/Indiana Geological Survey 10063, locality 3, sample 10, Brassfield Formation, Madison County, Kentucky, USA (Rexroad, 1967, pl. 4, fig. 3).


Occurrence.—Middle Ordovician to Ludlow (Mellgren, 2010).


Remarks.—Serrated Panderodus elements, which develop denticles along the posterior margin, have been considered various species. Rexroad (1967) considered Pa. serratus a subspecies of Pa. unicostatus, noting the only difference being denticulation on the posterior margin. Cooper (1975) considered Pa. serratus a multi-element apparatus consisting of denticulate and adenticulate coniform elements. Nowlan and Barnes (1981),


McCracken and Barnes (1981), and Nowlan et al. (1988) classified Pa. serratus as a form taxon that might be a possible variant of Pa. gracilis (Branson and Mehl, 1933b). For further discussion and references concerning serrate Panderodus elements, see Mellgren (2010).


Panderodus unicostatus (Branson and Mehl, 1933a) Figure 3.11


1933a Paltodus unicostatus Branson and Mehl, p. 42, pl. 3, fig. 3.


1976 Panderodus unicostatus; Cooper, p. 213, pl. 1, figs. 1–7, 22.


1977 Panderodus unicostatus; Barrick, p. 56, pl. 3, figs. 1, 2, 5, 6.


1997 Panderodus unicostatus; Jeppsson, fig. 7.3. 2002 Panderodus unicostatus; Zhang and Barnes, p. 32, fig. 15. 1–15.24 (see for synonymy).


2003 Panderodus unicostatus; Pyle and Barnes, fig. 17.20– 17.23.


2002 Panderodus unicostatus; Pyle and Barnes, p. 86, pl. 20, figs. 15, 16.


2005 Panderodus unicostatus; Dahlqvist and Bergström, p. 16, fig. 12n, o.


2006 Panderodus unicostatus; Valentine et al., p. 230, figs. 10p, 11a–b (see for synonymy).


2007a Panderodus unicostatus; Zhang and Barnes, fig. 10.16– 10.22.


2007b Panderodus unicostatus; Zhang and Barnes, fig. 8.21– 8.28.


2009 Panderodus unicostatus; Corriga and Corradini, fig. 6O.


2009 Panderodus unicostatus; Munnecke and Männik, fig. 5X–Z.


2010 Panderodus unicostatus; Wang and Aldridge, pl. 6, figs. 1–18.


2010 Panderodus unicostatus; Corradini and Corriga, pl. 1, figs. 19, 20.


2011 Panderodus unicostatus; Zhang, fig. 17.26–17.31. 2012 Panderodus unicostatus; Slavík and Carls, fig. 3V. 2013 Panderodus unicostatus; Jarochowska et al., fig. 2.17. 2013 Panderodus unicostatus; Zhang, fig. 10.8–10.14. 2014 Panderodus unicostatus; Harris et al., fig. 8D, E. 2014 Panderodus unicostatus; Sullivan et al., figs. 6.5, 6.6, 7.17–7.19.


2014 Panderodus unicostatus; Zhang and Pell, figs. 6.9–6.14, 10.14, 10.16.


Cotypes.—Paltodus unicostatus, University of Missouri C153-3, Bainbridge Formation, Lithium, Missouri, USA (Branson and Mehl, 1933a, pl. 3, fig. 3).


Occurrence.—Occurs globally from the Upper Ordovician to Early Devonian (Zhang and Barnes, 2002; Zhang, 2011, 2013).


Description.—Panderodus unicostatus has previously been described by Cooper (1976), and Barrick (1977).


1995 Panderodus unicostatus; Simpson and Talent, p. 118, pl. 2, figs. 1–32 (see for synonymy).


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