Siboglinidae Caullery 1914

?Family Siboglinidae Caullery, 1914 (?vestimentiferan)

‘Prince Patrick tubes’

(Fig. 11C, F, G)

1992 serpulid worm tubes Beauchamp & Savard: 438, figs 2a, 5a, 8c, d.

Material. NRC C-453952 1-4, Prince Patrick Island, many small tubes cemented together in a large bundle. NRC C-453961 PPL, C-453989 PPL, tubes observed in thin section. Provided by S. E. Grasby.

Occurrence. Prince Patrick Island seep carbonates, Arctic, Canada. Christopher Formation, Lower Albian, Cretaceous (Beauchamp et al. 1989; Beauchamp & Savard 1992).

Description. Carbonate tubes mostly 1.0 mm in diameter, but tubes of up to 5 mm also occur in these clumps (Fig. 11C). Tubes are unattached, non-branching and non-agglutinated. Ornamentation of the tube walls is largely obscured due to surface mineralization. In thin section, the tube walls are very similar to those of the large tubes from the same deposit: they are mostly thick and comprise many superimposed layers (Fig. 11F), but some are thinwalled (Fig. 11G). Tube cross-sections are distinctly round (Fig. 11F) suggesting that tubes were originally rigid. Some of the smaller tubes contain small transparent spheres within their interior (Fig. 11G).

Remarks. Tubes from Prince Patrick Island have also been interpreted as having been made by serpulids (Beauchamp & Savard 1992). However, these tubes were probably not originally calcareous in composition due to the absence of chevron-like layering, their neatly laminated tube walls and the separation of wall layers in places, which is unlikely to occur in cemented mineral tubes. Although outer tube wall ornamentation could not be assessed, the at times thick walls that these tubes possess, in combination with the morphology of the tube cluster, suggest that they may represent the fossilized root portions of vestimentiferan tubes (cf. Fig. 8I). These tubes are resolved near siboglinid tubes in the PCA plot (Fig. 21) and near vestimentiferans in the less conservative cladistic analysis (Fig. 24B), and are therefore also tentatively assigned to the vestimentiferans.