Panderodus greenlandensis Armstrong, 1990

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

Panderodus greenlandensis Armstrong, 1990

Figure 7.14 -15

*1990 Panderodus greenlandensis ; Armstrong, fig. 33, figs. 1-8 of pl.15.

2007 Panderodus greenlandensis Armstrong ; Loydell, Kleffner, Mullins, Butcher, Matteson, and Ebert, fig. 6W.

2009 Panderodus greenlandensis Armstrong ; Munnecke and Männik, fig. 5T-W.

2009 Panderodus greenlandensis Armstrong ; Szaniawski, fig. 1B.

Description. Elements have a very broad basal cavity that tapers sharply towards the cusp. Striations are prominent on the walls of the basal cavity, and do not extend along length of entire element. A deep furrow runs most of the length of the element tapering from wide at the base to narrow farther up the cusp. Both the arcuatiform and the graciliform specimens are very robust and sharply curved. The aboral margin of the arcuatiform element is fairly flat until the point of maximum curvature. It has a pronounced, rounded costa on the furrowed face of the element. The cusp twists slightly towards the unornamented side of the element. The aboral margin of the graciliform element is smoothly curved. The white matter in the graciliform element is restricted to the middle of the cusp, does not extend to the tip, and extends down to the point of maximum curvature. See Armstrong (1990) for thorough description.

Remarks. Panderodus greenlandenis can be differentiated from large specimens of P. unicostatus by the shape of the basal cavity, which is larger, and tapers more strongly towards the cusp than that of P. unicostatus . Both species have striations, but those on P. greenlandensis are more pronounced and are restricted to the basal cavity region. The striations on P. unicostatus extend most of the way up the element.

Material examined. Two graciliform and four 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.