Asterolepis sp. 2

Olive, Sébastien, 2015, Devonian antiarch placoderms from Belgium revisited, Acta Palaeontologica Polonica 60 (3), pp. 711-731 : 722-723

Asterolepis sp. 2

Fig. 8 .

Material.— Unassigned plate of the trunk shield: IRSNB P.9260; Cd1: IRSNB P.9259. From Burtaux quarry, locality Alvaux, Mazy, Gembloux, Namur Province, Belgium. Alvaux Member, Bois de Bordeaux Formation, Givetian, Middle Devonian.

Description

Trunkshield.— Unassigned plate ( Fig. 8A ): The assignment of that plate is not possible due to the very bad preservation. It is a lateral plate of the trunk shield as indicated by the presence of two laminae separated by a strong angle.

1

2

Pectoral fin.—Dorsal central plate 1, Cd1 ( Fig. 8B ): A well preserved specimen is available. It is rather long. The external dorsal articular area anterior to the unornamented area, is finely covered with tiny meshes. The posterior margin, articulating with the dorsal central plate 2, is concave. The margin, articulating with the medial marginal plate 2 is elongated and strongly concave, as in Asterolepis ornata . On the lateral margin, the lateral corner is quite prominent. The medial margin is slightly damaged but no spine is observable.

Ornament.— The ornament of Asterolepis sp. 2 is rather reticulate. On the unassigned plate, the ornament also consists of fine, rounded and flat tubercles arranged in a concentric and radiating pattern.

Remarks.—The shape of the dorsal central plate and the rounded, flat tubercles of the ornamentation support the Asterolepis identification. The dorsal central plate strongly resembles the dorsal central plate of A. ornata ( Gross 1931: pl. 5: 1a). Possibly, the specimens from Mazy could belong to the same form as the one from Hingeon. The amount and quality of the material in both localities is unfortunately not sufficient to confirm this conclusion.

Figures

Fig. 8. Dermal plates of antiarch placoderm Asterolepis sp. 2., from Mazy (Namur Province), Givetian, Devonian. A. IRSNB P.9260, unassigned plate, external view; photograph (A1); explanatory drawing (A2). B. IRSNB P.9259, CD1, external view. Scale bars 10 mm.