Gomphonchus Gross, 1971

Burrow, Carole J., 2003, Earliest Devonian gnathostome microremains from central New South Wales (Australia), Geodiversitas 25 (2), pp. 273-288 : 280

Genus Gomphonchus Gross, 1971

TYPE SPECIES. — Gomphodus sandelensis Pander, 1856 .

Gomphonchus sandelensis ( Pander, 1856) SYNTYPES. — Scales figured by Pander (1856: pl. 6, figs 15-17) from the Late Silurian (Pridoli) Ohesaare Formation, Saaremaa, Estonia. These types have been lost.

MATERIAL EXAMINED ( Table 1). — Four scales in sample C923, 13 scales in C925 including figured specimen MMMC 02561 ( Fig. 3C, D ) and two scales in C937.

DESCRIPTION ( FIG. 3C, D )

The scales are about 0.4 mm wide and long. The crown is horizontal, forming a smooth surface without ridges; some scales have a shallow medial sulcus on the anterior crown edge. The posterior part of the crown extends behind the base. The neck is of medium height, concave all round, and with vertical “buttresses” posteriorly. The base/neck rim is sharp, and the base bulges slightly forward of the crown. The base is convex, resembling a rounded, upturned pyramid which flattens out towards the base/neck rim, and is always smaller in area than the crown.

REMARKS

G. sandelensis is widespread throughout northern Europe, being recorded from Upper Silurian (Ludlow) through Lower Devonian (Emsian) strata of the Baltic countries, Byelorussia, Ukraine, the Central Devonian Field, Timan-Pechora and Taimyr in Russia (e.g., Valiukevic˘ius 1999, 2000), southern Great Britain (Vergoossen 1999a, 2000) and Spain ( Mader 1983), and also from Arctic Canada (Vieth 1980) and possibly Greenland ( Blom 1999). Vergoossen (1999a, b, 2000) delved into the difficulties of Gomphonchus taxonomy, erecting several new species and resurrecting one old species; the scales described herein are deemed to be G. sandelensis s.s.

Figures

FIG. 3. — Acanthodian tooth and scales from sample C925, Cookeys Plains Formation (early Lochkovian), central New South Wales, Australia; A, B, Nostolepis sp. tooth whorl MMMC02560 in occlusal (lingual edge at top) and posterior and lingual views; C, D, Gomphonchus sandelensis (Pander, 1856) scale MMMC02561 in crown and lateral views, with anterior edge to the left (crown riddled with hyphal borings); E, Trundlelepis sp., horizontal ground thin section of scale crown MMMC02562, anterior edge to left; F, G, Gomphonchoporus hoppei (Gross, 1947) scale MMMC02563 in crown and posterior views, anterior edge at top; H, I, Radioporacanthodes porosus (Brotzen, 1934) s.s. scale MMMC02564 in antero-crown and anterior views. Abbreviation: p, pore rows. Scale bars: 0.1 mm.