Annelida Lamarck, 1809

Georgieva, Magdalena N., Little, Crispin T. S., Watson, Jonathan S., Sephton, Mark A., Ball, Alexander D. & Glover, Adrian G., 2019, Identification of fossil worm tubes from Phanerozoic hydrothermal vents and cold seeps, Journal of Systematic Palaeontology 17 (4), pp. 287-329 : 13-14

?Phylum Annelida Lamarck, 1809

Family incertae sedis

‘Sibay tubes’

( Fig. 17 )

1999c Indeterminate annelid? tube Little, Maslennikov, Morris, & Gubanov: 1061, figs 4, 5.

Material. NHMUK VF71, cluster of tubes. Collected by C. T. S. Little.

Occurrence. Sibay massive sulphide deposit, southern Ural Mountains, Russia (52 º 41.66 ' N, 58 º 38.15 ' E). Middle-Lower Devonian ( Little et al. 1999c; Shpanskaya et al. 1999).

Description. Pyritic tubes 0.3–7.0 mm in diameter, nontapering, sometimes gently curved and with smooth walls ( Fig. 17A, B ) ( Little et al. 1999c). The tube walls were originally described to be formed of fine-grained pyrite which is occasionally colloform ( Little et al. 1999c). In thin sections examined during the present study, the tube walls appear thick and may be multi-layered ( Fig. 17C ), and some also appear to be comprised of framboidal pyrite ( Fig. 17D ).

Remarks. These tubes exhibit few distinguishing characteristics, which led to their previous diagnosis as indeterminate?annelid tubes ( Little et al. 1999c). As we were unable to find further characters, the tubes were largely unresolved within cluster and cladistic analyses ( Figs 22 , 24 ). The indeterminate status of the tubes is therefore maintained. They are tentatively suggested to be annelid tubes due to their smooth, thick and possibly multi-layered walls, and as they do not closely resemble the tubes of other Palaeozoic tubicolous animals.

Figures

Figure 17. ‘Sibay tubes’, NHMUK VF71, Devonian, Sibay, Russia. A, hand specimen showing cluster of tubes in various orientations. B, detail of tube wall showing smooth appearance. C, detail of the walls of three adjacent tubes in transverse section; walls appear thick and multi-layered. D, detail of framboidal pyrite preserving tube walls. Scale bars: A = 3 mm; B = 1 mm; C = 500 µm; D = 10 µm.

Figure 22. Strict consensus cladogram of the three most parsimonious trees of tubes built by a total of 43 modern annelid taxa (best score = 14.344, consistency index = 0.308, retention index = 0.629). The analysis was based on the 48 mostly morphological tube characters and was performed using implied character weighting (k = 3). Numbers on nodes represent groups present/contradicted support values. Symbols/colours indicate taxonomic affinities.

Figure 24. Fourier transform infrared (FTIR) spectroscopy spectra of the organic tubes of vent and seep annelids. Spectra are offset on the absorbance axis, and key spectral absorbance peaks are labelled with the types of chemical bonds they represent: -NH, nitrogenhydrogen; -CH, carbon-hydrogen; -OH, oxygen-hydrogen. The regions of the tube analysed are as follows: Tevnia jerichonana (anterior, inner tube wall); Zenkevitchiana longissimi (middle, outer tube wall); Lamellibrachia anaximandri (posterior, outer tube wall); Sclerolinum contortum (anterior, outer tube wall); Alvinella sp. (middle); Spiochaetopterus izuensis (middle, outer tube wall).