Treatise Online, no. 36: Part E, Revised, Volume 4, Chapter 2E: Paleoecology of the hypercalcified chaetetid-type Porifera (Demospongiae)

West, Ronald R.

doi:10.17161/to.v0i0.4258

Cited by 2 publications

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“…Chaetetids were common reef-mound builders worldwide during the Early and Middle Pennsylvanian (West, 1988(West, , 2012bWahlman, 2002). Palaeozoic chaetetids share morphological features with many groups, including extant calcified demosponges, tabulate corals, stromatoporoids, hydrozoans, trepostome bryozoans and calcareous algae, and they have had a long and complex taxonomic history (for a review see Connolly et al, 1989;West, 2011a).…”

Section: Introductionmentioning

confidence: 99%

A new plate-like hypercalcified chaetetid demosponge (Loiscupula bachendensi gen. nov. sp. nov) from the Cantabrian Zone (Moscovian, Pennsylvanian, NW Spain)

Corrochano

West²

2013

Palaeontologia Electronica

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Loiscupula has a circular, concentric, platy basal skeleton, some with cylindrical features and chimneys, which sometimes branch on the upper surface. The basal skeleton is composed of polygonal (commonly hexagonal) to rounded tubules perpendicular to the surface of the skeleton producing the characteristic honeycomb pattern of chaetetids. Cathodoluminescence microscopy revealed non-luminescent calcite pseudomorphs of monoaxon and polyaxon spicules, rarely styles, which are irregularly distributed although there are occurrences that suggest that a spicular network existed. The basal skeleton is composed of neomorphic low-Mg calcite (1.7 mol% MgCO 3 ) and is strongly recrystallized; the tentative penicillate microstructure with relics of aragonite needles, and the high Sr content (up to 3456 ppm), suggest an original aragonite composition. Loiscupula is interpreted as primarily a gregarious organism with an inferred central point of attachment. This mode of growth produced small cryptic cavities between Loiscupula and the substrate, which were inhabited by encrusting organisms, mostly fistuliporid bryozoans. Based on the associated fossils and sedimentological features, it is suggested that Loiscupula inhabited an environment with a muddy bottom in the euphotic zone, where the water was well-oxygenated, of normal salinity, and the energy regime low to moderate.

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