Pterospathodus amorphognathoides angulatus ( Walliser, 1964 )

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 : 19-20

Pterospathodus amorphognathoides angulatus ( Walliser, 1964)

Figures 4.4, 4.6-4.9 , 10.1-10.7

*1964 Spathognathodus pennatus angulatus ; Walliser, pl. 14, figs. 19-22 (Pa element).

1998 Pterospathodus amorphognathoides angulatus Walliser ; Männik, pl. 2, figs. 1-22, 24-31 (multielement, synonymy through 1998).

2003 Pterospathodus amorphognathoides angulatus Walliser ; Loydell, Männik, and Nestor, fig. 14m.

2006 Pterospathodus amorphognathoides angulatus Walliser ; Hints, Killing, Männik, and Nestor, pl. 3, fig. 12.

2007 Pterospathodus amorphognathoides angulatus Walliser ; Loydell, Kleffner, Mullins, Butcher, Matteson, and Ebert, fig. 6a-d.

2007a Pterospathodus amorphognathoides angulatus Walliser ; Männik, fig. 8E-F.

2008 Pterospathodus amorphognathoides angulatus Walliser ; Männik, fig. 8O, U.

2010 Pterospathodus amorphognathoides angulatus Walliser ; Loydell, Nestor, and Männik, fig. 9r.

2014 Pterospathodus amorphognathoides angulatus Walliser ; Sullivan, Kleffner, and Brett, fig. 7.10.

2015 Pterospathodus amorphognathoides angulatus Walliser ; Männik, Loydell, Nestor, and Nõlvak, fig. 8Q.

Description. Sb 1 element tertiopedate. Posterior process denticulate, straight, and extended down away from the cusp. Outer lateral process with one large denticle, inner lateral process broken. Pb 2 element anguliscaphate, with fan-like denticles with fairly uniform height posterior and anterior to a well-developed cusp. Grooves between denticles visible almost down to the base of the element. Basal cavity narrow, extends length of element. Pb 1 element anguliscaphate, with well-developed cusp. Denticles extend at similar angles anterior and posterior to the cusp. Denticles anterior to the cusp are much higher than posterior denticles. Pa element blade-like, with 17 unevenly sized denticles. Denticles widest on anterior and posterior portions of blade. Pa elements from Metzger (2005) have at least 17 denticles, which is consistent with most morphotypes of the subspecies illustrated in Männik (1998). Denticles situated slightly anterior to the cusp are always much smaller than those posterior to the cusp. Height of blade below where the denticles fuse is similar on anterior and posterior processes.

Remarks. The Pb 1 element shown in Figure 10.4-5 was originally reported from the Garrison Core in Metzger (2005), but it was not illustrated. It was identified as a Pb 1 element of Pterospathodus amorphognathoides amorphognathoides , but we believe it compares more closely with Pb 1 elements of Pterospathodus amorphognathoides angulatus . Pb 1 elements of Pt. a. amorphognathoides have a very distinctive narrow platform that is situated just below the denticles on both sides of the anterior and posterior processes, and have a ridge that extends from the basal flare up the cusp. This specimen lacks both of those characteristics, and most closely resembles Pt. a. angulatus Pb 1 elements illustrated in text-figures 7F, 7P, or 8T in Männik (1998).

Material examined. One Sb 1, three Sc 1, one Sc 2?, four Pb 1, three Pb 2, one Pa, one Pa? elements.

Figures

FIGURE 4. Specimens reported from the DX5 outcrop section in Metzger (2005). All specimens in lateral view. 1-3, 5, Pterospathodus eopennatus ssp. n. 2 sensu Männik (1998), Pa element, DLH 4, SUI 132418 (1); Pa element, DLH 6, SUI 132420 (2); Pb element, DLH 6, SUI 132420 (3); and Pa element, DLH 9, SUI 132423 (5). 4, 6-9, Pterospathodus amorphognathoides angulatus, Pa element, DLH 6, SUI 132420 (4); Pb element, DLH 6, SUI 132420 (6); Pa element, DLH 6, SUI 132420 (7); Pb element, DLH 6, SUI 132420 (8); and Pa element, DLH 11, SUI 132425 (9). 10, Aulacognathus bullatus? Pb element, DLH 11, SUI 132425.

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.