Apalolepis undetermined

Burrow, Carole Jan, Murphy, Michael & Turner, Susan, 2023, Late Silurian to earliest Devonian vertebrate biostratigraphy of the Birch Creek II section, Roberts Mountains, Nevada, U. S. A., PaleoBios 40 (1975), pp. 1-32 : 23-24

APALOLEPIS SP.

( FIG. 7K, L ; TABLE 1)

Referred specimens —One scale, AMF97872 from BCII level 503’ (153.3 m) – this specimen is missing: Roberts Mountains Formation.

Description — Parkes (1995, p. 55, fig. 22.11, 12) correctly identified and described this broken scale. The

crown is flattened and smooth, the upper surface divided by simple ridges into a central part and two lateral fields, the ventral surface smooth. The crown rises gently to the posterior edge at about 20 degrees from the anterior edge. The neck is high and smooth. The base is typical for the genus, being anteriorly placed, small and rounded with a shallow torus and slightly anterior point.

Remarks — Vieth (1980) tentatively assigned one scale (not figured) from the Lochkovian Member A, Red Canyon River Formation to? Apalolepis . Elsewhere, Apalolepis taxa are only found in the Lochkovian ( Märss et al. 2007).

Figures

Figure 7. Thelodont scales from the uppermost Silurian of the Birch Creek II section, all level 430.5' except B, C, G, K, L, P, Q. A. Trimerolepis sp. cf. T. tricava. UCR 10746-43 in crown view. B. Trimerolepis sp. AMF97876 (Parkes 1995, fig. 22.19, 20) from level 503’, base view. C.?Lanarkia sp. UCR 944-20 (level 527.25’) in lateral view. D.?Turinia sp. UCR10746-19, showing taphonomic effects and ultrasculpture, in crown view. E-J. Nikolivia spp. E. UCR 10746-13 with cell pattern on surface in crown view; F, UCR 10746-20 in crown view; G, AMF97875 (Parkes 1995, fig. 22.17, 18) from level 402' with possible bite marks, in crown view; H, UCR 10746-27 in ventral basal view; I, UCR 10746-25 showing taphonomic effects in crown view; J, Nikolivia sp. cf. N. auriculata, UCR 10746-18 in crown view. K, L. Apalolepis sp. AMF97872 (level 503’) (Parkes 2005, fig. 22.11, 12), crown and basal views. M-O. Talivalia sp. cf. T. elongata. M, UCR 10746-17 in crown view; N, UCR 10746-37 in crown view; O, UCR 10746-21 in lateral view. P-S. Barlowodus sp. cf. B. tridens. P,Q, AMF97874 (level 875’) in crown and basal views (Parkes 2005, fig. 22.15, 16). R, S, UCR 944-21 (level 527.25') in laterocrown view, closeup in S showing striated ultrasculpture. Scale bars=0.2 mm; anterior to left or top, otherwise arrow points to anterior. See Table 1 for meterage.