Attachment structures in shells from the Ordovician and Silurian of Canada, Europe and Africa
2008 (English)In: Sixth International Bioerosion Workshop: Salt Lake City 13-20 July 2008, Program and Abstracts, Idaho: Idaho State University , 2008, 36- p.Conference paper (Other academic)
Shallow pits occur in gastropod and trilobite shells from the Middle Ordovician to Late Silurian of eastern Canada, western Europe and northern Africa. Despite their widespread occurrence, these pits have gone relatively unnoticed in the literature. Individual pits typically are 200-350 μm ovals with a lobate outline, penetrating steeply to a uniform depth of 20-30 μm. The base of the pits are sculptured by an irregular lattice of more deeply penetrating, narrow (~3 μm) fissures that separate less deeply penetrating angular regions that are 5-15 μm in width. Pits always occur in multiples and form an irregular array with no apparent alignment. Adjacent pits typically are spaced more than one pit diameter away (300-500 μm) and they rarely abut one another. Pits appear to be postmortem structures occurring both on the inside and outside of shells. Although the size range and general shape of the pits is similar to some dendrinid microborings described from the Paleozoic, their wide surface aperture suggests that these pits were most likely attachment structures. The rough microsculpturing formed by the fissures at the base of the pits increases the surface area of shell exposed to the tracemaker, a feature that would be advantageous as an anchoring mechanism. These pits differ from named Paleozoic traces attributed to brachiopods and bryozoans (e.g., Podichnus and Ropalonaria) by their shallower penetration, irregular shape, and lack of consistent pit arrangement.
Place, publisher, year, edition, pages
Idaho: Idaho State University , 2008. 36- p.
IdentifiersURN: urn:nbn:se:uu:diva-10121OAI: oai:DiVA.org:uu-10121DiVA: diva2:37889
Sixth International Bioerosion Workshop, 13-20 July, 2008, Salt Lake City