PLATE 17.
Structura and hypothetical stages of three-edged spines formation
of the subfamily Spongopolyentactiniinae (Spongentactinella olafi Afanasieva)
Upper Devonian, Middle Frasnian, Domanik Formation. The Lyajol River, outcrop no. 1904, sample 6: fig. 1, 2; borehole Shuda-Yag-1003: fig. 3, 4 - sample 8 (depth 120.9-124 m), fig. 5-7 - sample 72 (depth 71.9-72.4 m).
1. Spines with Y-shaped final (1, 2) and middle (3, 4) cross-section
Fig. 1, 2 - FF-P001/056-09633, 1 - (bar=20µm), 2 - detail (=7µm).
Fig. 3, 4 - FF-P001/056-04125, 3 - (=15µm), 4 - detail (=7µm).
2. Spines with three-petalled basal cross-section (5-7)
Fig. 5-7 - FF-P001/056-08514, 5 - (=15µm), 6, 7 - detail (=4µm). |
