Monograph: Reassessment of Dyads Contained in a Late Silurian Rhyniophytoid Sporangium

A sporangial cluster of dyads of PH doli age, first described by Lang in 1937, was investigated using Confocal Laser Scanning Microscopy (CLSM) supplemented by additional transmitted white light microscopy. CLSM images were most useful in determining the topology of an internal membrane found in well-preserved spore pairs. Detailed morphological characterization failed to resolve unambiguously either the ploidy or the botanical affiliation of these spores, but comparison with other fossils indicates a rhyniophytoid affinity for this sporangium, and that the included spores are most probably meiospores.