FIGURE 1. Locality map (left) and local stratigraphy of the Castle Bank locality, showing occurrence of Teganium avalonensis sp. nov. within the Castle Bank sequence (mainly siltstone, with shading representing colour of sediment; v: volcanic ash layers). Exact locality information is deposited with the specimens.
FIGURE 2. Teganium avalonensis sp. nov., from the Middle Ordovician Castle Bank Biota, Wales. A-B: paratype slab NMW.2021.3G.72, with pair of sponges in A, plane-polarised light, and B, cross-polarised; C, E, holotype NMW.2021.3G.71: C, overall view, with box indicating area enlarged in E; E, detail of basal region showing projecting basalia; D, paratype NMW.2021.3G.73, overall view. Scale bars: A-D equal 5 mm; E equals 1 mm.
FIGURE 3. Teganium avalonensis sp. nov. A, paratype NMW.2021.3G.74; apical part with marginalia, imaged with directed light (from right) to highlight texture of body wall; B, paratype NMW.2021.3G.98, with low-angle light to highlight diagnostic texture of body wall (boxed area enlarged inset); C-F, paratype NMW.2021.3G.82, partial specimen with the boxes in C indicating positions of D, E and F; D, lateral detail to show reticulate skeletal grid (plane-polarised light); E, detail showing scale of minute triaxon spicules within the same area; centres of several spicules arrowed; F, detail of central part of specimen in cross-polarised light (contrast enhanced) to highlight the small circular cavities within choanosomal (internal) layer of body wall. Scale bars: A, B, D, F equal 1 mm; C equals 5 mm; E equals 0.1 mm.
FIGURE 4. Paratypes of Teganium avalonensis sp. nov. A, NMW.2021.3G.77; B, NMW.2021.3G.98 in cross-polarised light (boxed area enlarged in Figure 3B); C, NMW.2021.3G.78 with pair of specimens, the right-hand one with marginalia; D, NMW.2021.3G.79; E, NMW.2021.3G.81 with multiple specimens, in cross-polarised light; F, NMW.2021.3G.80. Scale bars equal 1 mm.
FIGURE 5. Cut-away reconstruction of Teganium avalonensis sp. nov., with detail of wall structure on the right; dermal/hypodermal skeleton in lower part, and choanosomal layer with exhalent canals in upper part.
FIGURE 6. Teganium sp., from the Middle Ordovician Castle Bank Biota, Wales. A, NMW.2021.3G.76i and ii, overall view, with positions of detail images indicated by boxes (all rotated). B, apex of NMW.2021.3G.76i, apex of sponge showing extensive marginalia; C, detail of body wall showing characteristic texture (boxed area enlarged inset); D, apex of NMW.2021.3G.76ii, with oscular margin and trace of marginalia. Scale bars: A equals 10 mm; B-D equal 1 mm.
FIGURE 7. Palaeogeographic distributions of species of Teganium (all species in B originally assigned to Teganiella). A, Ordovician (Sandbian, 458 Ma). B, Carboniferous (Visean, 340 Ma). Map constructed using GPlates (Müller et al. 2018) using data from Torsvik & Cocks (2016). Does not include unconfirmed taxa listed by Ruedemann (1925b, 1934, 1942).
