The relationship of the stromatoporoids to the sclerosponges
Article first published online: 9 OCT 2007
Volume 5, Issue 4, pages 369–388, October 1972
How to Cite
STEARN, C. W. (1972), The relationship of the stromatoporoids to the sclerosponges. Lethaia, 5: 369–388. doi: 10.1111/j.1502-3931.1972.tb00868.x
- Issue published online: 9 OCT 2007
- Article first published online: 9 OCT 2007
Similarities of the extinct strornatoporoids to the sponges of the recently established order Sclerospongia have strengthened arguments that these fossils are closer to the Porifera than to the Coelenterata. Major features favouring the affinity of the stromatoporoids to the sclerosponges include: (1) lack of evidence of colonialism in the strornatoporoids, (2) similarity of gross structure of some stromatoporoids to that of one sclerosponge (Astrosclera), (3) fibrous microstruc-ture of sclerosponges, Mesozoic stromatoporoids, and some Paleozoic stromatoporoids, (4) similarity of stromatoporoid astrorhizae to the excurrent canals of sclerosponges. Points of dissimilarity include: (1) the solid aragonitic skeletons of most sclerosponges, (2) the presence of dissepiments, laminae, and latilaminae in stromatoporoids, (3) the absence of siliceous spicules in stromatoporoids.
These comparisons suggest that the stromatoporoids were basically encrusting filter feeders like the sclerosponges but had progressed by loss of spicules and periodic introduction of dissepirnents and laminae toward a secretion of a skeleton of the coelenterate type. They cannot be placed with confidence in either the sclerosponges or the hydrozoans and should be recognized us a separate subphylum of the Porifera.