Scolopodus striatus Pander, 1856

Zhen, Yong Yi, 2011, Middle to Late Ordovician (Darriwilian-Sandbian) Conodonts from the Dawangou Section, Kalpin Area of the Tarim Basin, Northwestern China, Records of the Australian Museum 63 (3), pp. 203-266 : 253-254

Scolopodus striatus Pander, 1856

Fig. 26A–W

? Scolopodus costatus Pander, 1856: 26 , pl. 2, fig. 7a–d, pl. A, fig. 5e.

Scolopodus semicostatus Pander, 1856: 26 , pl. 2, fig. 4a–b.

Scolopodus aequilateralis Pander, 1856: 26 , pl. 2, fig. 5a–c, pl. A, fig. 5c.

Scolopodus quadratus Pander, 1856: 26 , pl. 2, fig. 6a–d, pl. A, fig. 5d; Fåhraeus, 1982a: 21, pl. 2, figs 1–14, pl. 3, figs 1–8, 15 (cum syn.); Rasmussen, 2001: 131, pl. 17, fig. 12; Zhen et al., 2003b: 212, fig. 27A–O (cum syn.); Zhen et al., 2004a: 58–59, pl. 5, figs 15–21 (cum syn.).

Scolopodus striatus Pander, 1856: 26 , pl. 2, figs 8a–d, pl. A, fig. 5f; Tolmacheva, 2006: 255–259, figs 5A–B, D,?E, F, 6–8 (cum syn.); Viira, 2011: fig. 11E.

Scolopodus rex Lindström, 1955a: 595–596 , pl. 3, fig. 32; van Wamel, 1974: 94, pl. 5, fig. 18; Landing, 1976: 640, pl. 4, fig. 14; Löfgren, 1978: 109–110, pl. 1, 38–39; An, 1981: pl. 3, fig. 10; An & Ding, 1982: pl. 1, fig. 22; Zeng et al., 1983: pl. 12, fig. 35; An et al., 1985: pl. 10, figs 8, 13; An, 1987: 187, pl. 7, figs 1–4, 6–8, pl. 9, fig. 6; Ding, 1987: pl. 5, fig. 20; Ni & Li, 1987: 440, pl. 57, figs 23, 32–34; Stouge & Bagnoli, 1990: 25, pl. 9, figs 1–6; Duan, 1990: pl. 2, fig. 6; Gao, 1991: 140, pl. 7, fig. 1; Ding et al. in Wang, 1993: 205, pl. 14, figs 21–26; Löfgren, 1994: fig. 7.1; Chen & Bergström, 1995: pl. 7, fig. 7; Wang et al., 1996: pl. 2, figs 18–19; Wang & Bergström, 1999 a: 342, pl. 2, fig. 14; Zhao et al., 2000: 224, pl. 14, figs 2–8.

Scolopodus rex var. paltodiformis Lindström, 1955a: 596 , pl. 3, figs 33–34.

Paltodus scolopodiformis Sergeeva, 1974 : pl. 1, figs 10–11. Scolopodus multicostatus Ni in Ni & Li, 1987: 439, pl. 58, fig. 6.

? Scolopodus praerex Ni in Ni & Li, 1987: 440, pl. 57, figs 51–54.

Material. 37 specimens from five samples of the Dawangou Formation (see Table 1).

Remarks. As revised by Tolmacheva (2006), Scolopodus striatus consists of a quinquimembrate apparatus including scandodiform M ( Fig. 26R–W ), acontiodiform P ( Fig. 26A–B ), subrounded Sa ( Fig. 26C–D ), and paltodiform and compressed paltodiform S (undifferentiated) elements. Tolmacheva (2006, fig. 2) further differentiated the compressed paltodiform element into short-based and long-based variants, and the paltodiform element into short-based and medium-based variants. Her short-based paltodiform element (Tolmacheva, 2006, fig. 7A) exhibits a multicostate inner lateral face and smooth outer lateral face; such features are identical with those exhibited by what she defined as the M element, although that is more strongly compressed with a shorter, but more expanded base. We regard the scandodiform element and short-based variant of the paltodiform element as representing the M element, whereas the medium-based variant of the paltodiform element is interpreted as occupying the Sc position ( Fig. 26J–O ). The long-based variant of the compressed paltodiform element is assigned to the Sd position ( Fig. 26P–Q ), and the short-based variant of the compressed paltodiform element is regarded as the Sb element ( Fig. 26E–I ).

The M element from the Dawangou section ( Fig. 26R–W ) is identical with the short-based variant of Tolmacheva’s paltodiform element (2006, fig. 7A). Both have an anteroposteriorly compressed cusp and a short base. The convex anterior face is smooth ( Fig. 26U ) or only faintly costate basally (fig. 24S), and the posterior face is less convex but strongly costate ( Fig. 26R, T, V–W ). The typical scandodiform element defined by Tolmacheva (2006, fig. 6F–G, fig. 8D–F) has not been recognized in our Tarim material.

Figures

Figure 26. Scolopodus striatus Pander, 1856. A–B, P element (acontiodiform), NIGP 153092, Nj294, A, anterior view (IY148-14), B, posterior view (IY148-015). C–D, Sa element (subrounded), NIGP 153093, Nj294, C, posterior view (IY148-012), D, postero-lateral view (IY148-011). E–I, Sb element (short-based variant of compressed paltodiform); E–G, NIGP 153094, Nj294, E, inner lateral view (IY148-007), F, posterior view (IY148-008), G, antero-outer lateral view (IY148-006); H–I, NIGP 153095, Nj294, H, outer lateral view (IY148-029), I, upper view showing cross section of cusp (IY148-028). J–O, Sc element (medium-based variant of paltodiform); J, NIGP 153096, Nj292, inner lateral view (IY158-025); K–L, NIGP 153097, Nj292, K, inner lateral view (IY158-022), L, outer lateral view (IY158-020); M–O, NIGP 153098, Nj294, M, basal view of basal cavity (IY148-017), N, outer lateral view (IY148-016), O, inner lateral view (IY148-018). P–Q, Sd element (long-based variant of compressed paltodiform), NIGP 153099, Nj294, P, inner lateral view (IY148-009), Q, basal view of cusp (IY148-010). R–W, M element (short-based variant of paltodiform); R–S, NIGP 153100, Nj294, R, inner lateral view (IY148-004), S, outer lateral view (IY148-005); T–U, NIGP 153101, Nj292, T, inner lateral view (IY158-023), U, outer lateral view (IY158-024); V, NIGP 153102, Nj295, inner lateral view (IY149-009); W, NIGP 153103, Nj294, inner lateral view (IY158-031). Scale bars 100 µm.