Re-examination of seed cuticles from Cretaceous deposits in West Greenland

Abstract

Just over 60 years ago Miner described several species of plant microfossils from Cretaceous strata in West Greenland (Disko Island) which he placed in two genera, Chrysotheca(now Costatheca) and Spermatites. Although he, and a number of other authors subsequently, questioned their affinities, his species Spermatites arcuatus, S. ellipticus, S. elongatus, S. nanus, S. orbicularis, S. ovatusand S. pylophorusare today widely thought to be cuticular seed coats. The affinity of the only species of Costathecahe diagnosed, C. diskoensis,is more problematic. Although his specimens may also be seed cuticles, similar fossils from other Upper Cretaceous successions that have been assigned to this species might have different origins. It is possible that some are insect eggs. All eight taxa are typical late Early to Late Cretaceous morphotypes, but the lack of detail in Miner's descriptions has hampered their identification in coeval plant microfossil assemblages elsewhere, and their differentiation from other taxa erected subsequently. Hence, revised descriptions supplemented by illustrations of selected type and some new material from West Greenland, and comments on the characters that distinguish the species of Spermatitesare presented here. Both their morphology and relative abundance in Upper Cretaceous deposits suggest that they may well have angiospermous origins. Costatheca diskoensisis also discussed but, apart from one scanning electron micrograph, it is not illustrated because the two slides containing the type material have not been located.