Drepanoistodus sp.

Zhen, Yong Yi, Percival, Ian G. & Webby, Barry D., 2003, Early Ordovician Conodonts from Far Western New South Wales, Australia, Records of the Australian Museum 55 (2), pp. 169-220 : 194

Drepanoistodus sp.

Fig. 14L

Material. Four specimens from limestone nodules within shales of the upper Yandaminta Quartzite , and four specimens from the Tabita Formation, at Mount Arrowsmith; an additional specimen from unnamed dolomitic limestone unit at Koonenberry Gap .

Remarks. Specimens of a large suberect element, here identified as Drepanoistodus sp. ( Fig. 14L ), are asymmetrical with the basal cavity inflated inner-laterally and with an undulose basal margin at the inner side. Löfgren (1978) noticed some variations among Swedish specimens assigned to the P element of D. basiovalis . Some forms showing a flaring anterobasal corner ( Löfgren, 1978, pl. 1, fig. 13), are comparable with the elements here referred to D. sp. This element might occupy the Pa position to complete a seximembrate apparatus for D. basiovalis .

Figures

Fig. 14. A–K, Drepanoistodus basiovalis (Sergeeva, 1963): A,B, P element, AMF120351, Y4–2, A, outer lateral view, B, basal view; C, Sb element,AMF120352, M/A7, outer lateral view; D–F, P element,AMF120354,W5, D, outer lateral view, E, posterior view, F, inner lateral view; G, Sa element, AMF120356, M/A11-3, lateral view; H, P element, AMF120355, Y4–2, outer lateral view; I, Sc element, AMF120358, M/A11-2, inner lateral view; J, M element, AMF120357, Y4–2, anterior view; K, M element, AMF120353, A/M11–3, posterior view. L, Drepanoistodus sp., AMF120360, W5, outer lateral view. M–O, Ulrichodina sp. cf. simplex Ethington & Clark, 1982, AMF120359, W5, M,N, lateral views, O, basal view. Scale bars 100 µm.