Turinia 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 : 22

? TURINIA SP.

( FIG. 7D ; TABLE 1 ; SUPPL. 1, FIGS. 5 , 9 )

Referred specimens —Possibly three scales in BCII section: two at level 430.5’ (131.2 m) and one at 456.5’ (139.1 m): Roberts Mountains Formation.

Description —One scale in 430.5’ is a robust trunk scale with the posterior tip broken off, by which the central large pulp canal can be seen. The base is extended anteriorly into a wide spur. A further possible trunk scale is boat-shaped with a poorly preserved crown with prominent ridges and a median narrow platform, a wide shallow neck and a small anterior prong on the large ellipsoid base ( Fig. 7D ). A broken trunk scale from level 456.5’ has a posteriorly expanding and possibly high crown. The undersurface of the posterior crown in a trunk scale has a strong median rib and three to four lateral ones (Suppl. 1, fig. 9). There is a broken anterior rounded base with a large pulp opening.

Remarks —These few scales resemble those of the type species and might be Turinia pagei but their preservation is poor and/or they are broken and this taxon does not usually occur below the Siluro-Devonian boundary. Turiniid scales with several ventral crown ribs are also seen in Turinia barentsia from the Lower Devonian Red Bay Group of Spitsbergen ( Blom and Goujet 2002, e.g., pl. 1.6, 8). Turinia -like scales have been recorded in some localities such as the Welsh Borders and Irian Jaya ( Märss et al. 2007, Turner et al. 2017).

Figures

Figure 5. Funicristata nevadaensis n. gen. n. sp. from the uppermost Silurian of the Birch Creek II section. A–C. UCR 10750-3 (level 456.5') in crown views and magnified view of the crown ridges; D, E. UCR 10750-2 (level 456.5') in crown and lateral views; F, G. UCR 10746-10 (level 430.5') in anterocrown and crown views; H, I. UCR 10746-8 (level 430.5') in anterocrown and laterocrown views; J, K. UCR 10750-10 (level 456.5') vertical longitudinal section; L. UCR 10750-12 (level 456.5') horizontal section through crown. Abbreviations: c=canal; en=enameloid; h=hyphal boring; po=pore openings. Scale bars=0.1 mm in A, B, D–L, 0.01 mm in C; anterior is to left or down, otherwise arrows point to anterior. See Table 1 for meterage.

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.

Figure 9. Paleogeographic reconstruction for the late Silurian, base map from Scotese (2014, map 73), showing possible vertebrate dispersal route from the Baltic to the circum-Arctic and thence south to western Laurentia.