A century of seed ferns: A symposium to celebrate paradigm shifts in the understanding of seed plant
Pigg, Kathleen B. , Nishida, Harufumi .
The significance of silicified plant remains to the understanding of Glossopteris-bearing plants.
Since the late 1960s when silicified Permian plant remains were first recovered in the central Transantarctic Mountains and the Bowen Basin of Australia, they have played a pivotal role in our understanding of Glossopteris leaf-bearing plants.Schopf's 1970 Science paper announcing the Antarctic discovery and his work on glossopterid reproductive structures and Vertebraria pioneered the study of these Gondwana permineralized fossils with the same techniques and approaches used with Euramerican coal-ball plants. Subsequent work by the Taylor lab illuminated new aspects of Antarctic glossopterids including the presence of polyembryony. Reconstruction of stems with Araucarioxylon wood and attached leaves of G. skaarensis demonstrated that Glossopteris plants produced paired branch traces that fuse distally much like those of cordaites, and extend into axillary branches bearing closely spaced, helically arranged leaves. Studies by Drinnan and associates in the Prince Charles Mountains have suggested that the glossopterids that occupied eastern Antarctica may have been distinct from those in the central Transantarctic Mountains. Coeval floras in Australia provided the material from which Gould and Delevoryas described permineralized glossopterid ovules borne on fertile leaves, supporting a seed fern affinity for glossopterids, and further stimulating earlier speculation that Glossopteris might be an early ancestor of the angiosperms. During the 1980s, Glossopteris continued to play an important role in phylogenetic hypotheses of seed plants. In the early 1990s Pigg and McLoughlin documented the presence of both widespread distribution of two Antarctic leaf species, G. schopfii and G. skaarensis, into the Bowen and Sydney Basins of Australia, and the narrower distribution of G. homevalensis within the Bowen Basin. Last year Nishida and colleagues contributed to the ongoing paradigm shift in our understanding of glossopterid relationship by documenting evidence of motile gametes ("swimming sperm").
1 - Arizona State University, School of Life Sciences, PO Box 874501, Tempe, Arizona, 85287-4501, USA
2 - Chuo University, Faculty of Science and Engineering, 1-13-27 Kasuga, Bunkyo, Tokyo, 112-8551, JAPAN
Presentation Type: Symposium
Location: Ballroom 1 (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 8:45 AM