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The structure of the sporopollenin wall of fossil megaspores can be usefully applied to the determination of morphological similarities and differences between species and genera, which in turn can aid determinations of botanical relationships. Nine species belonging to seven genera of lycopsid megaspores from European Mesozoic successions that have been examined in thin section under a transmission electron microscope are discussed in this paper. Of these, seven are considered to be referable to the Selaginellales, namely Bacutriletes pragensis, Echitriletes zemechensis, Erlansonisporites sp. ‘pseudomoravica’ type, Horstisporites cenomanicensis, Kerhartisporites kleinii, K. srebrecensis, Ricinospora sp. and Verrutriletes maloninensis. The structure of the exospore of Aneuletes patera, an alete species of hitherto uncertain affinity, also suggests that this has selaginellalean origins. The construction of the wall of Echitriletes lanatus, however, resembles that of representatives of the Isoetales and imp...

This paper presents data on the stratigraphic ranges of all known Mesozoic and Tertiary megaspores from around the world and demonstrates the potential of these palynomorphs for dating and correlating sedimentary sequences. Forms referable to more “natural”; genera such as Ariadnaesporites and Paxillitriletes, as opposed to those that are based solely on sculptural morphology, are particularly important because not only are they among the most reliable of biostratigraphic indicators but they also have the greatest value to biologists concerned with the evolution of heterosporous plants. There is, however, much work to be done before megaspores can be used on a regular basis for solving geological problems.

The poorly consolidated clastic sediments of Late Cretaceous age in the vicinity of Asen, southern Sweden (Scania) are noted for the variety of fossil flowers and Normapolles pollen grains they have yielded. Megaspores have also been recovered from a number of horizons. Comments on, and illustrations of all but a few indeterminate remains of these are provided in this paper, and four new species, Bacutriletes ferulus, B. majorinus, Erlan‐sonisporites scanicus and E. septus, are erected. Comparison of the total recovery with the relatively small number of Late Cretaceous assemblages that have been described from elsewhere reveals only a few taxa in common. As a result, it is not possible to improve on the late Santonian‐early Campanian age determination that has already been established for the Asen deposits. It is reasonable to infer from the wall structure of the majority of the spores that they were shed by plants of either selaginellalean or isoetalean affinity. Their distribution within the A...

Rationalization of the taxonomy of pollen grains referable to Papillopollis has been necessary so that the majority of specimens encountered in the Senonian succession of Portugal can be identified. Revised diagnoses are provided for P. aradaensis Kedves & Pittau, P. aveiroensis Kedves & Pittau, P. minimalis Pacltova & Krutzsch, P. rugulatus Kedves & Pittau and P. santonius Pacltova & Krutzsch; one new species, P. barbosae, is erected. The degree of morphological variation allowed for these species is greater than in previous descriptions of forms of Papillopollis and enables the removal of seventeen other taxa which lack reliable distinguishing characters by placing them in synonymy. The sculpture of the pollen grains described ranges from essentially granulate to minutely papillate. The sexine at the poles is typically fissured or reduced to small granular or papillate masses or bodies, but can be absent altogether. These areas of modified exine may have had a harmomegathic function. Thin secti...