Stromatoporoid Growth Rhythms and Rates

Stromatoporoids are major contributors to framework construction in Paleozoic reefs. The Devonian species Parallellostroma densilaminata (Fagerstrom), P. winchelli (Galloway and Ehlers), and Stictostroma sp. form large rhythmically structured colonies that competitively overgrow corals. Their competitive interactions and important role as reef builders place considerable value on growth rate information. Identification of common growth periods in these interacting species provides a method for quantifying vertical and lateral stromatoporoid growth and a means for identifying an annual periodicity of calcification.