The significance of silicified plant remains to the understanding of Glossopteris-bearing plants: An historical review

Anatomically preserved fossils from the Late Permian basins of Antarctica and eastern Australia have played a pivotal role in our understanding of Glossopteris-bearing plants since their discovery in the late 1960s. The first studies, from the Bowen Basin of Queensland by Gould and Delevoryas, showed that permineralized glossopterid ovules are borne on fertile leaf-like structures, suggesting to these authors a "seed fern" affinity for them. Based on vascular bundle orientation, it is now clear that ovules are borne on the adaxial surface of fertile structures, and more recent study has documented that they are often borne on small stalks. Plectilospermum, an Antarctic seed, was shown to exhibit simple polyembryony. With the recent discovery of evidence for swimming sperm in Australian ovules, our understanding of glossopterid reproduction continues to develop. Although whole plant reconstructions are not yet known for individual glossopterid plants, we can now document, in part, information about the plants that bore G. schopfii, G. skaarensis, and G. homevalensis leaves.