Erraticodon sp. A

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 : 198

Erraticodon sp. A

Fig. 18A–G

Material. Five specimens (1 Pa, 1 Pb, 2 Sa, 1 Sc?) from the Tabita Formation at Mount Arrowsmith.

Description. Pa element digyrate, with a long posterior process bearing three or more peg-like widely spaced and posteriorly inclined denticles ( Fig. 18C,D ); cusp oval in cross section, slightly twisted inward, with a sharp anterior margin, which extends basally into a short anticusp; inner lateral side bearing a long process with three or more peglike, widely spaced denticles which are anteroposteriorly compressed and distally rather sharply curved inward. Pb element modified digyrate, with a longer inner lateral process bearing three or more widely spaced, peg-like denticles, and a short outer lateral process with a single denticle; anterior process also short and represented by a single denticle ( Fig. 18A,B ); cusp and denticles curved posteriorly. Sa element alate, symmetrical, with a robust cusp, a denticulate posterior process, and lateral processes on each side bearing a small denticle ( Fig. 18F,G ). Sc element possibly represented by a poorly preserved specimen with a short anterior process bearing a single denticle, and a posterior process with three or more, long, posteriorly reclined denticles ( Fig. 18E ).

Remarks. This species is rare in the Tabita fauna, with only Pa, Pb, Sa and a doubtful Sc element recovered. It can be easily differentiated from the co-occurring E. patu by having widely spaced denticles, a short anterior process in the Pb element, and a laterally compressed cusp with a prominent anticusp in the Pa element . Although possibly a new species, formal designation is deferred pending recovery of all element types.

Figures

Fig. 18. A–G, Erraticodon sp.A:A,B, Pb element,AMF120391, M/A7, A, anterior view, B, posterior view; C,D, Pa element,AMF120392, M/A7, C, posterior view, D, upper view; E, Sc? element, AMF120393, M/A7, outer lateral view; F,G, Sa element,AMF120394, M/A7, posterolateral views. H–J, Jumudontus gananda Cooper, 1981: H, Pa element, AMF120395, M/A4, lateral view; I, Pb element, AMF120397, C1611, basal lateral view; J, Pa element, AMF120396, C1611, lateral view. Scale bars 100 µm.