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Fig. 3 | Swiss Journal of Palaeontology

Fig. 3

From: Siphonal tube structure of the Late Devonian orthocerid Dolorthoceras from the Polar Urals (NW Russia) preserving nacre and organic fibres as well as its persistence in cephalopod evolution

Fig. 3

Dolorthoceras sp. (PIN-1894/100); River Malaya Usa, Polar Urals, NW Russia; Frasnian, Late Devonian. Median conch section. Columnar nacre in the septum and the shell wall indicates the exceptional preservation of this orthocone. Note that the tablets of nacre are, as in present day Nautilus, larger in the septa than in the shell wall. Scale bar is 30 µm. ch chamber, hsd hyposeptal cameral deposits, ipl inner prismatic layer, m matrix, md mural cameral deposits, nl nacreous layer, opl outer prismatic layer, s septum, sw shell wall

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