Trundlelepis sp.
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publication ID |
https://doi.org/ 10.5281/zenodo.5376020 |
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persistent identifier |
https://treatment.plazi.org/id/020087A6-324F-3119-FC89-FC0149DCFA42 |
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treatment provided by |
Marcus |
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scientific name |
Trundlelepis sp. |
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MATERIAL EXAMINED ( Table 1). — Nine scales in sample C864, one scale in C866, one scale MMMC 02554 ( Fig. 4G, H View FIG ) in C923, three scales and one ground thin section MMMC 02562 ( Fig. 3E View FIG ) in C925, and one scale in Y4.
DESCRIPTION
Morphology ( Fig. 4G, H View FIG )
The scales are relatively large, being up to 1.0 mm wide and long, with a horizontal crown bearing regularly-spaced ridges along the anterior edge; the ridges are placed radially relative to the posterior corner of the crown. Some scale crowns (not figured) have denticulated postero-lateral edges. The neck is deep and concave all round, with vertical buttresses on the posterior face, and most scales have a large convex base which bulges forward of the crown. Scale MMMC02554 has a diagonal ridge, or accessory growth zone, leading down and forwards from the posterior limit of the crown.
Histology ( Fig. 3E View FIG )
The histological structure of the scale sectioned is of typical Gomphonchus - type, with finelybranching dentine tubules filling the crown.
REMARKS
The scales resemble the most common morphotype in the original material of T. cervicostulata Burrow, 1997 from the Connemarra Formation (late Lochkovian-early Pragian) in this region of central New South Wales. However, some of the scales have accessory growth zones off the postero-lateral edges of the crown ( Fig. 4G, H View FIG ) which are a distinguishing feature, in combination with radial canals, of scales of Gomphonchoporus Vergoossen, 1999 . Such accessory growth zones are noted on scale variants of many Early Devonian taxa – e.g., Nostolepis taimyrica Valiukevicius, 1994 (Pragian-Emsian), N. athleta Valiukevicius, 1994 (Lochkovian-Pragian) and N. tcherkasovae Valiukevicius, 1994 (Lochkovian) from Tareya, Russia (Valiukevic˘ius 1994: pl. XVIII, fig. 5; pl. XIX, fig. 14; pl. XX, fig. 4 respectively) – and also on scales of Nostolepis halli Blom, 1999 ( Blom 1999: fig. 29A, B, D, E) from the Late Silurian (Pridoli) Chester Bjerg Formation, Hall Land, north Greenland. The scales described here also resemble scales from Lochkovian deposits of Arctic Canada which Vieth (1980: pl. 6, fig. 15) assigned to Gomphonchus cf. hoppei . Once again, the small number of scales in the assemblages studied here, and the probability of similar forms occuring within the morphological range of several taxa, preclude a definite taxonomic assignment. Perhaps the scales are from a biological taxon showing scale characters which are transitional between the older, more cosmopolitan species and the younger endemic species.
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