A foraminiferal fauna from siliceous sponge remains, collected in modern sponge bioherms on the continental shelf off British Columbia, Canada, are compared with assemblages reported from Late Jurassic sponge reefs in central and southern Europe. Forty arenaceous and 53 calcareous taxa were found either loose in, attached to, trapped within or engulfing parts of the meshwork. Specimens found loose belong to the same species as present in the surrounding mud or nearby on the shelf. The most common attached, trapped or engulfing genera are Crithionina, Gaudryina, Karreriella, Placopsilina, cf. Tritaxis, Trochammina, Islandiella, Lobatula and Ramulina. Two new taxa are described and illustrated: Placopsilina spongiphila n. sp. and Ramulina siphonifera n. sp. The main genera attached or closely associated with Jurassic reefal sponges are Vinelloidea, Thurammina, Tolypammina, Tritaxis, Subbdelloidina and Bullopora. Comparison of Recent and Jurassic sponge reef foraminiferal assemblages indicate that there are no taxa in common at the species level and few at the genus level. However, foraminifera from both the Recent and the Jurassic seem to have interacted with the sponge meshwork in a way that taxa are attached to, trapped in, laced-in and to a certain extent engulf the meshwork. Many ecological niches seem to have remained essentially unchanged since the Jurassic in the dead sponge meshwork environment with new taxa substituting themselves into niche spaces to replace taxa that went extinct.
Jean-Pierre Guilbault. BRAQ-Stratigraphie, 37 chemin Cochrane, Compton, QC, Canada H3L 3K4.
Manfred Krautter. Institut für Geologie und Paläontologie, Universität Stuttgart, Herdweg 51, 70174 Stuttgart, Germany.
Kim W. Conway. Geological Survey of Canada, P.O. Box 6000, Sidney, BC, Canada V8L 4B2.
J. Vaughn Barrie. Geological Survey of Canada, P.O. Box 6000, Sidney, BC, Canada V8L 4B2.
KEYWORDS: reefs, benthic foraminifera, convergent evolution, Canada, British Columbia, Europe, hexactinellid sponges, encrusting species, epifauna.
PE Article Number: 9.1.3A
Copyright: Paleontological Society. February 2006
Submission: 28 July 2004. Acceptance: 24 December 2005.
