Fahraeusodus adentatus ( McTavish, 1973 )

Zhen, Yong Yi & Nicoll, Robert S., 2009, Biogeographic and Biostratigraphic Implications of the Serratognathus bilobatus Fauna (Conodonta) from the Emanuel Formation (Early Ordovician) of the Canning Basin, Western Australia, Records of the Australian Museum 61 (1), pp. 1-30 : 13

Fahraeusodus adentatus ( McTavish, 1973)

Fig. 6I–K, S–V

? Microzarkodina adentata McTavish, 1973: 49 , 50, pl. 3, figs 28, 33–35, 38–40, 42–44.

Fahraeusodus adentatus (McTavish) .— Stouge & Bagnoli, 1988: 119, pl. 4, figs 12–14 (cum syn.); Lehnert, 1995:89, pl. 7, fig. 20A, 20B.

Material. Seven specimens from two samples ( Table 1).

Remarks. Specimens representing the asymmetrical Sb element with a lateral costa on the outer lateral face ( Fig. 6T ), the strongly asymmetrical Sc element without a lateral costa on each side ( Fig. 6S ), and the asymmetrical Sd element with a costa on each side ( Fig. 6U, V ) were recovered in the two samples from the Emanuel Formation.A specimen representing the triform Sa element with a broad, nearly flat anterior face and with a sharp anterolateral costa on each side ( Fig. 6I–K ) is also assigned to this species. McTavish (1973) recognized a quinquimembrate apparatus including oistodiform (= M element), ozarkodiniform (= P element), trichonodelliform (= Sa element), cordylodiform (= Sc element), and tetraprioniodiform (= Sd element), and doubtfully assigned it to Microzarkodina . Stouge & Bagnoli (1988) proposed Fahraeusodus and selected? M. adentata as the type species. However, only a few specimens were recovered in the upper part of Bed 9 ( O. elegans Biozone ) of the Cow Head Group in Newfoundland, an interval stratigraphically slightly younger than the occurrence in the Emanuel Formation. The flat anterior face and edge-like anterolateral costa on each side of the Sa element are comparable with some specimens referred to Fahraeusodus marathonensis by Stouge & Bagnoli (1988, e.g., pl. 4, fig. 15) from the Cow Head Group.

Figures

Fig. 6. A–F, Paracordylodus gracilis Lindström, 1955. All from sample WCB705/243. (A), M element, CPC39827, anterior view (IY116-050). B–E, S elements; B–C, CPC39828, (B), inner lateral view (IY116-051); (C), close up showing chevron-shaped pattern of striae adjacent to anterior margin (IY126-052); (D), CPC39829, inner lateral view (IY126-053); (E), CPC39830, outer lateral view (IY126-054); (F), P element, CPC39928, outer lateral view (IY116055). G,H,L, Prioniodus adami Stouge & Bagnoli, 1988. G,H, Pa element, CPC39831, WCB705/243, (G), antero-outer lateral view (IY118-018); (H), outer lateral view (IY118-019). (L), Sa element, CPC39832, WCB705/243, posterior view (IY128-021). M–R, Protoprioniodus simplicissimus McTavish, 1973. All from sample WCB705/243. M, N, Sc element; (M), CPC39833, outer lateral view (IY118-020); (N), CPC39834, inner lateral view (IY118-030). O,P, Pa element, CPC39835, (O), inner lateral view (IY118-025); (P), upper-outer lateral view (IY118-023). Q,R, M element; (Q), CPC39836, anterior view (IY129-032); (R), CPC39837, posterior view (IY118-029). I–K, S–V, Fahraeusodus adentatus (McTavish, 1973). I–K, Sa element, CPC39838, WCB705/133, (I), lateral view (IY127-012); (J), anterior view, close up showing striae on the broad anterior face (IY127-011); (K), anterior view (IY127-010). (S), Sc element, CPC39839, 161–166 m, inner lateral view (IY130-001). (T), Sb element, CPC39840, 161–166 m, outer lateral view (IY130-002). U,V, Sd element, CPC39841, 161–166 m, (U), inner lateral view (IY130-005); (V), outer lateral view (IY130-006). Scale bars 100 µm unless otherwise indicated.