The origins of the five groups of living seed plants, including the single relictual species Ginkgo biloba, are poorly understood, in large part because of very imperfect knowledge of extinct seed plant diversity. Here we describe well-preserved material from the Early Cretaceous of Mongolia of the previously enigmatic Mesozoic seed plant reproductive structure Umaltolepis, which has been presumed to be a ginkgophyte. Abundant new material shows that Umaltolepis is a seed-bearing cupule that was borne on a stalk at the tip of a short shoot. Each cupule is umbrella-like with a central column that bears a thick, resinous, four-lobed outer covering, which opens from below. Four, pendulous,winged seeds are attached to the upper part of the column and are enclosed by the cupule. Evidence from morphology, anatomy, and field association suggests that the short shoots bore simple, elongate Pseudotorellia leaves that have similar venation and resin ducts to leaves of living Ginkgo. Umaltolepis seed-bearing structures are very different from those of Ginkgo but very similar to fossils described previously as Vladimaria. Umaltolepis and Vladimaria do not closely resemble the seed-bearing structures of any living or extinct plant, but are comparable in some respects to those of certain Peltaspermales and Umkomasiales (corystosperms). Vegetative similarities of the Umaltolepis plant to Ginkgo, and reproductive similarities to extinct peltasperms and corystosperms, support previous ideas that Ginkgo may be the last survivor of a once highly diverse group of extinct plants, several of which exhibited various degrees of ovule enclosure.
Herrera, F., Chicago Botanic Garden, Glencoe, IL 60022, United States; Shi, G., Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China; Ichinnorov, N., Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar-51, Mongolia; Takahashi, M., Department of Environmental Sciences, Faculty of Sciences, Niigata University, Ikarashi, Nishi-ku, Niigata, 950-2181, Japan; Bugdaeva, E.V., Institute of Biology and Soil Science, Far East Branch, Russian Academy of Sciences, Vladivostok, 690022, Russian Federation; Herendeen, P.S., Chicago Botanic Garden, Glencoe, IL 60022, United States; Crane, P.R., School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, United States, Oak Spring Garden Foundation, Oak Spring, Upperville, VA 20184, United States
Recommended Citation:
Herrera F.,Shi G.,Ichinnorov N.,et al. The presumed ginkgophyte Umaltolepis has seed-bearing structures resembling those of Peltaspermales and Umkomasiales[J]. Proceedings of the National Academy of Sciences of the United States of America,2017-01-01,114(12)