Panderodus panderi ( Stauffer, 1940 )

Waid, Christopher B. T. & Cramer, Bradley D., 2017, Telychian (Llandovery, Silurian) conodonts from the LaPorte City Formation of eastern Iowa, USA (East-Central Iowa Basin) and their implications for global Telychian conodont biostratigraphic correlation, Palaeontologia Electronica 42 (6), pp. 1-37 : 24-25

Panderodus panderi ( Stauffer, 1940)

Figure 7.3-5

1975 Panderodus panderi Stauffer ; Sweet Sweet, Thompson, Satterfield, pl. 1, fig. 12 (synonymy through 1975).

1977 Panderodus panderi Stauffer ; Barnes, pl. 3, fig. 21.

1981 Panderodus panderi Stauffer ; Nowlan and Barnes, pl. 6, figs. 3-4, 14.

1994 Panderodus panderi Stauffer ; Bauer, fig. 4.31- 4.32.

1995 Panderodus panderi Stauffer ; Zhen and Webby, pl. 3, figs. 23-25.

2002 Panderodus recurvatus Rhodes (1953) ; Zhang and Barnes, fig. 16.1-16.27 (synonymy of P. recurvatus through 1995).

2004 Panderodus recurvatus Rhodes ; Farrell, pl. 3, figs. 9, 12-13.

2007b Panderodus recurvatus Rhodes ; Zhang and Barnes, fig. 10.27-10.23.

2009 Panderodus recurvatus Rhodes ; Corriga and Corradini, fig. 6P.

2010 Panderodus panderi Stauffer ; Wang and Aldridge, pl. 5, figs. 1-17.

2012 Panderodus recurvatus Rhodes ; Corradini and Corriga, fig. 6A.

2015 Panderodus panderi Stauffer ; Jarochowska and Munnecke; fig. 8W.

Description. The point of maximum curvature in falciform, tortiform, and arcuatiform elements occurs approximately at the halfway point of the length of the specimens. The point of maximum curvature on graciliform elements is roughly 2/3 to 3/4 of the distance from the base to the cusp. The posterior margin of arcuatiform elements relatively straight before and after the point of maximum curvature. The posterior margins of the other element types curve continuously along the length of the elements. In all element types, white matter extends from the tip of the cusp down to, or near, the point of maximum curvature. Fine striations extend from the base most of the way to the white matter. Furrows terminate at a conspicuous notch at the base of the specimens. The elements are moderately laterally compressed. See Zhang and Barnes (2002) and Jeppsson (1997) for thorough descriptions and species diagnoses.

Remarks. We follow the suggestion of Jeppsson (1997) that P. recurvatus is a junior synonym of P. panderi . Zhang and Barnes (2002) suggested that P. recurvatus may not be a member of genus Panderodus , if their inclusion of double-furrowed elements that lack lateral costae in the apparatus is valid. No specimens were recovered fitting this description.

The distribution of white matter and the lateral extent of striations can be used to distinguish P. panderi from small specimens of P. greenlandensis . The white matter extends all the way to the tip of the cusp in P. panderi , and the striations are not restricted to the walls of the basal cavity, as they are for P. greenlandensis . Striations on the base are much more pronounced on P. greenlandensis .

Material examined. One falciform, twenty-three graciliform, twelve truncatiform, and five arcuatiform elements.

Figures

FIGURE 7. Simple cone elements from Garrison Core. All specimens in lateral view except for 6. 1-2, Panderodus equicostatus, graciliform, GC 124.66–124.93 m, SUI 142251 (1) and graciliform, GC 121.92-121.88 m, SUI 142253 (2). 3-5, Panderodus panderi, graciliform, GC 124.66–124.93 m, SUI 142252 (3); arcuatiform, GC 131.95–132.23 m, SUI 142254 (4); and graciliform, GC 111.38–111.63 m, SUI 142255 (5). 6, Psuedooneotodus beckmanni, oral view, GC 135.65–136.10 m, SUI 142256. 7, Panderodus cf. P. unicostatus, falciform, GC 135.65–136.10 m, SUI 142257. 8- 11, Panderodus unicostatus, falciform, GC 131.95–132.23 m, SUI 142258 (8); fused cluster of 8 elements, GC 130.20–130.48 m, specimen destroyed processing for SEM (9); fused cluster of 6 elements, GC 131.95–132.23 m, SUI 142260 (10); and tortiform element, GC 131.95–132.23 m, SUI 142261 (11); 12-13, Walliserodus curvatus, dyscritiform, GC 134.06–134.31 m, SUI 142262 (12) and curvatiform, GC 128.85–129.11 m, SUI 142263 (13). 14-15, Panderodus greenlandensis, arcuatiform GC 118.20–118.41 m, SUI 142264 (14) and graciliform, GC 134.06–134.31 m, SUI 142265 (15). White scale bar represents 0.5 mm.