Kockelella, Walliser, 1957

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 : 23-24

Kockelella cf. K. abrupta ( Aldridge, 1972) sensu Aldridge (1972)

Figure 10.22 -23

1972 Spathognathodus cf. S. abruptus ; Aldridge,

1972, pl. 4, fig. 8 (Pa element).

2005 Kockelella cf. K. abruptus (Aldridge) ; Metzger,

pl. 1, figs. 18-20.

Description. P 1 element blade-like, very slightly bowed in oral view. Lower profile of element straight in lateral view except around basal cavity. Denticles closely spaced, not fused, and fairly uniform in size along length of element. Anterior process makes up the majority of the blade, and the posterior process consists of four denticles at a slightly different orientation than those on the anterior process. Basal cavity is very small and flares outwardly into a small, asymmetric basal platform where the outer side is larger than the inner. The posterior-most denticles are distinctively shorter than the rest of the denticles.

Remarks. Aldridge (1972) recorded a single Fronian age (= upper Aeronian to lower Telycian) Spathognathodus specimen from the Llandovery type area in Wales, with a morphology similar to P 1 elements of both Kockelella ranuliformis ( Walliser, 1964) , and Kockelella abruptus ( Aldridge, 1972) . Metzger (2005) and this study recovered three specimens from the DX5 outcrop area nearly identical to the one from Aldridge (1972, plate 4, figure 8), together with conodonts diagnostic of the Pterospathodus eopennatus ssp. n. 2 and Pt. amorphognathoides angulatus zones (lower to middle Telychian).

Aldridge (1972) considered Spathognathodus cf. abruptus to be a transitional form between S. abruptus and S. ranuliformis Walliser (1964) . The occurrence of this morphology in the same interval in the East-Central Iowa Basin provides further evidence for this hypothesis. Too few specimens exhibiting this morphology have been found to officially assign it a species or subspecies classification with adequate description, but this distinctive morphology may provide biostratigraphic utility.

Material examined. One P 1 element.

Figures

FIGURE 10. Conodonts from the Garrison Core and DX5 outcrop. 1-7, Pterospathodus amorphognathoides angulatus, Sc1 element, posterior view, GC 115.51–115.76 m, SUI 142304 (1); Pb1? element, lateral view, GC 115.51– 115.76 m, SUI 142305 (2); Pb2 element, GC 111.38–111.63 m, SUI 142306 (3); Pb1 element, inner lateral, and oral views, GC 115.51–115.76 m, SUI 132410 (4 and 5); Pa element, oral view, DX5 3.49–3.59 m, SUI 142307 (6); and Pa element, lateral view, DX5 4.59–4.61 m, SUI 142308 (7). 8-19, Pterospathodus eopennatus ssp. n. 2 sensu Männik (1998), Sb2 element, posterior, and lateral views, GC 130.79–131.09 m, SUI 142309 (8 and 9); Sc1 element, lateral view, GC 130.79–131.09 m, SUI 142310 (10); M element, GC 130.79–131.09 m, SUI 142311 (11); Pb1 element, lateral view, GC 128.85–129.11 m, SUI 142312 (12); Pc element, lateral view, GC 130.20–130.48 m, SUI 142313 (13); Pb1 element, lateral view, GC 130.20–130.48 m, SUI 142314 (14); Pa element, lateral view, GC 128.85–129.11 m, SUI 142315 (15); Pb1 element, lateral view, GC 130.20–130.48 m, SUI 142316 (16); Pa element, lateral, and oral views, GC 130.79–131.09 m, SUI 142317 (17 and 18); and Pa element fragment, oral view, GC 130.20–130.48 m, SUI 142318 (19). 20-21, Aulacognathus sp., juvenile P1 element, oral, and lateral-anterior views, GC 135.65–136.10 m, SUI 142319. 22-23, Kockelella cf. K. abrupta, P1 element, oral, and lateral views, DX5 0.67–0.74 m, SUI 142320.