Porifera-microbialites of the Lower Liassic (Northern Calcareous ...
Porifera-microbialites of the Lower Liassic (Northern Calcareous ...
Porifera-microbialites of the Lower Liassic (Northern Calcareous ...
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Plate 11<br />
Adnet / Rot-Grau-Schnöll Quarry –<br />
Lyssacinosid sponge types from <strong>the</strong> Hettangian Schnöll Formation (Adnet/Rot-Grau-Schnöll<br />
Quarry).<br />
(A): Small specimens showing no distinct wall structure, only dermal and gastral layers with<br />
higher concentration <strong>of</strong> spicules. Skeleton type 1.<br />
(B): Transverse section <strong>of</strong> a sponge specimen showing <strong>the</strong> skeleton type 2. In <strong>the</strong> centre large-<br />
scaled monaxons are arranged in circles and bundles (arrow).<br />
(C): Sector <strong>of</strong> a sponge wall. Cross-section <strong>of</strong> a tubular or cup-shaped species. High densities <strong>of</strong><br />
spicules and long-shafted hexactins characterize <strong>the</strong> skeleton type 3.<br />
(D): Sponge specimens showing <strong>the</strong> skeleton type 4. Canals <strong>of</strong> <strong>the</strong> aquiferous system are filled<br />
with light grey sediments. Microbialites in former sponge tissue area show highest<br />
concentration <strong>of</strong> pyrite at <strong>the</strong> boundary to <strong>the</strong>se canals.<br />
(E): Sponge specimen <strong>of</strong> skeleton type 5. The former mesohyle shows very thin-rayed<br />
hexactins. Similar pentactin gastralia (arrows) are aligned to <strong>the</strong> edges <strong>of</strong> round pores.<br />
(F): Detail <strong>of</strong> Pl. 10B (arrow). Ostia <strong>of</strong> a sponge specimen that shows features <strong>of</strong> skeleton types<br />
3 and 4. Arrow = dermal layer with higher density <strong>of</strong> thick-rayed spicules.
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