Oulodus cf. petilus

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 : 26

Oulodus cf. petilus pacificus Savage, 1985

Figure 8.14, 8.16 -17

Description. Sb element digyrate. Inner lateral process extends slightly down and curves back towards the cusp. Outer lateral process slightly curved and extends away from the cusp. Cusp prominent, round to slightly oval in cross section. Denticles are widely spaced, uneven in size, and slightly oval in cross section. Basal cavity large and expanded posteriorly under cusp. Sc element bipennate with anterior process sharply curved inwards and down. Posterior process extends straight behind cusp. Both processes denticulate, with unevenly sized, evenly spaced denticles that are slightly oval in cross section. Cusp prominent and oval in cross section. Pb element digyrate. Outer lateral process fairly straight and extends sharply down from cusp. Inner lateral process curved away from cusp. Denticles and cusp slightly oval in cross section.

Remarks. The extended processes and widely spaced denticles on the Sc element, and the geometry of the processes on the Pb element are comparable to Oulodus petilus pacificus Savage (1985 , figure 11G-H, 11C-D). The curvature of the lateral processes of the Sb element ( Figure 8.16 ) is similar to the specimen shown in figure 11I-J in Savage (1985), but the denticles are not oriented outwardly as much as that shown in Savage (1985). One difference of all the specimens with those illustrated in Savage (1985) is that the denticles are slightly more circular in cross section.

Material examined. One Sb, one Sc, one Pb element.

Figures

FIGURE 8. Conodonts from the Garrison Core. 1-12, 19, Psuedolonchodina sp. n., Sa element, posterior view, GC 115.51–115.76 m, SUI 152266 (1); Sa element, posterior-aboral view, GC 121.62–121.88 m, SUI 142267 (2); Sb element, anterior view, GC 134.06–134.31 m, SUI 142268 (3); Sc element, lateral view, GC 130.20–130.48, SUI 142269 (4); Sc/M? element fragment, lateral view, GC 128.85–129.11 m, SUI 142270 (5); M element, lateral-posterior view, GC 131.95–132.23 m, SUI 142271 (6); M element, anterior-lateral view, GC 134.06–134.31 m, SUI 142272 (7); Pa element, oral view, GC 134.06–134.31 m, SUI 142273 (8); Pa element, oral view, GC 130.79–131.09m, SUI 142274 (9); Sc element, lateral view, GC 135.65–136.10 m, SUI 142259 (10); Pb element, lateral, and lateral-aboral views, GC 115.51–115.76 m, SUI 142275 (11 and 12); and Pb element, lateral view, GC 130.79-131.09 m, SUI 142276 (19). 13, 15, Oulodus sp. indet., Sa element, anterior-lateral view, GC 137.12–137.40 m, SUI 142277 (13) and Pa element, posterior view, GC 135.65–136.10 m, SUI 142278 (15). 14, 16-17, Oulodus cf. Ou. petilus pacificus, Sc element, lateral view, GC 134.06–134.31 m, SUI 142279 (14); Sb element, posterior-oral view, GC 130.20–130.48 m, SUI 142280 (16); and Pb element, anterior-lateral view, GC 130.79–131.09 m, SUI 142281 (17). 18, 21-22, Distomodus staurognathoides, Sb element, posterior view, GC 134.06–134.31 m, SUI 142282 (18); Pa element, oral view, GC 135.65– 136.10 m, SUI 142283 (21); and Pa element, oral view, GC 135.65–136.10 m, SUI 142282 (22). 20, Aulacognathus angulatus, P2 element, lateral view, GC 135.65–136.10 m, SUI 142285.