Panderodus unicostatus (Branson and Mehl, 1933)

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 : 25-26

Panderodus unicostatus (Branson and Mehl, 1933)

Figure 7.8-11

*1933a Paltodus unicostatus ; Branson and Mehl, pl. 3 fig. 3.

1997 Panderodus unicostatus Branson and Mehl ; Smelror, Cocks, MØrk, Neuman, and Nakrem, fig. 11D.

2002 Panderodus unicostatus Branson and Mehl ; Zhang and Barnes, fig. 15.1-15.24 (synonymy through 1995).

2004 Panderodus unicostatus Branson and Mehl ; Farrell, pl. 4, figs. 10-13.

2007b Panderodus unicostatus Branson and Mehl ; Zhang and Barnes, fig. 10.16-10.22.

2009 Panderodus unicostatus Branson and Mehl ; Corriga and Corradini, fig. 6O.

2009 Panderodus unicostatus Branson and Mehl ; Munnecke and Männik, fig. 5X-Z.

2010 Panderodus unicostatus Branson and Mehl ; Wang and Aldridge, pl. 6, figs. 1-18.

2015 Panderodus unicostatus Branson and Mehl ; Jarochowska and Munnecke, fig. 7L, 8G-H.

2016 Panderodus unicostatus Branson and Mehl ; Waid and Over, fig. 3.28.

Description. Posterior margins of all element types except for arcuatiforms are gently curved along entire length. The posterior margin of arcuatiform elements are generally straight. Falciform elements are markedly more robust than other element types and have slightly laterally compressed basal cavities. Tortiform elements orally compressed with the cusp twisting away from the face with a subtle furrow. Aequaliform elements are small yet robust and symmetrical with furrows on each face. Graciliform elements are more slender than other element types and exhibit a varying degree of curvature. Truncatiform elements are similar to graciliform elements, but smaller, and more curved. White matter extends 1/4 to 1/3 of the length of the element from the tip in all element types. Furrows are wide at the base and narrow towards the tip of the element. Fine striations are visible along the entire length of specimens. See Cooper (1975), Barrick (1977), and Sansom et al. (1994) for thorough description and apparatus reconstruction.

Remarks. Panderodus unicostatus was the dominant coniform species throughout the majority of the LaPorte City Formation. Several fused clusters of P. unicostatus were recovered. Most of the elements within the clusters appear to be currentaligned (e.g., Figure 7.10 ), indicating that they are not in the orientation that they were in the conodont animal. Two clusters were recovered that are not imbricated (e.g., Figure 7.9 ), indicating that the elements may be in orientations similar to their orientations in the organism.

Material examined. Two aequaliform, twenty tortiform, seventeen falciform, seventy-six graciliform, sixteen truncatiform, fourteen 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.

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.

FIGURE 9. Conodonts from the Garrison Core and DX5 outcrop. 1-8, Wurmiella? polinclinata polinclinata, S0 element, anterior view, GC 130.79–131.09 m, SUI 142286 (1); S1/2 element, posterior view, GC 115.51–115.79 m, SUI 142287 (2); S3/4 element, lateral view, GC 115.51–115.76 m, SUI 142288 (3); M element, lateral view, GC 130.20– 130.48 m, SUI 142289 (4); P2 element, lateral view, GC 130.20–130.48 m, SUI 142290 (5); P2 element, GC 130.79– 131.09 m, SUI 142291 (6); P1 element, lateral view, DX5 4.59–4.61 m, SUI 142292 (7); and P1 element, lateral view, DX5 3.49–3.59 m, SUI 142293 (8). 9-10, Aulacognathus angulatus, P1 element, oral view, GC 135.65–136.10 m, SUI 142294 (9) and S1/2? element, posterior view, GC 135.65–136.10 m, SUI 142295 (10). 11-14, Aulacognathus bullatus, P2 element, lateral view, DX5 1.34–1.54 m, SUI 142296 (11); P1 element, oral view, DX5 4.59–4.61 m, SUI 142297 (12); P1 element, oral view, DX5 0.67–0.74 m, SUI 142298 (13); and P1 element, oral view, GC 120.88– 121.13 m, SUI 142299 (14). 15-16, Aulacognathus kuehni, P1 element, oral view, GC 131.95–132.23 m, SUI 142300 (15) and juvenile P1 element, oral view, GC 131.95–132.23 m, SUI 142301 (16). 17, Astrolecignathus cf. milleri, Pa element, oral view, GC 121.92–121.88 m, SUI 142302. 18, Apsidognathus tuberculatus, Pa element, oral view, DX5 1.34–1.54 m, SUI 142303.

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.

FIGURE 11. P1 elements of Wurmiella? polinclinata estonica and Wurmiella? polinclinata polinclinata. 1-11 are classified as W.? polinclinata polinclinata. 12 and 14 show some characteristics of each subspecies, but compare most closely to W.? polinclinata polinclinata. 13, 15-17 are classified as W.? polinclinata estonica. All specimens in lateral view. 1, GC 121.92–121.88 m, SUI 142321; 2, GC 128.85–129.11 m, SUI 142322; 3-5, GC 130.20–130.48 m, SUI 142323 (3), 142324 (4), and 142325 (5); 6, GC 130.79–131.09 m, SUI 142326; 7-11, GC 131.95–132.23 m, SUI 142327 (7), 142328 (8), 142329 (9), 142330 (10), and 142331 (11); 12-14, GC 134.06–134.31 m, SUI 142332 (12), 142333 (13), and 142334 (14); and 15-17, GC 135.65–136.10 m, SUI 142335 (15), 142336 (16), and 142337 (17).