Aulacognathus sp.

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

Aulacognathus sp.

Figure 10.20 -21

Description. P 1 element slightly stellate, blade slightly bowed in oral view, with an outer lateral lobe and an anteriorly-oriented inner lateral process. Denticles in center of blade slightly taller than those towards the posterior or anterior ends of the element. Inner lateral process contains small denticles. Outer lateral lobe without ornamentation. Basal cavity wide and highly excavated under basal platform.

Remarks. The geometry of the blade and inner lateral process and highly excavated basal cavity is similar to many species of Aulacognathus . However, no features diagnostic of a species within Aulacognathus are present. The specimens are very small and are interpreted as being juveniles, so either the specimens may represent a heretofore undescribed species, or diagnostic features are not developed.

Material examined. Two P 1 elements.

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.