A new gnetalean macrofossil from the Early Cretaceous and its evolutionary significance |
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| Affiliation: | 1. School of Earth and Environment, Anhui University of Science & Technology, Huainan 232001, China;2. School of Earth Sciences, Lanzhou University, Lanzhou 730000, China;3. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, CAS, Nanjing 210008, China;1. Université de Lyon, F-69622 Lyon, France;2. Université Lyon 1, Villeurbanne, France;3. CNRS, UMR 5276 Laboratoire de Géologie de Lyon, Herbiers de l''Université Claude-Bernard Lyon 1, 7-9 rue raphaël Dubois, 69622 Villeurbanne Cedex, France;4. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, China;1. University of Vienna, Department of Palaeontology, Althanstrasse 14 (UZA II), 1090 Wien, Austria;2. Swedish Museum of Natural History, Department of Palaeobiology, P.O.Box 5007, 10405 Stockholm, Sweden;3. Nelson-Mandela Metropolitan University, Centre for Coastal Palaeoscience and Botany Department, PO Box 77000, Port Elizabeth 6031, South Africa |
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| Abstract: | Modern gnetophytes consist of three families, i.e. the Ephedraceae, the Gnetaceae, and the Welwitschiaceae, which show diversified morphology. The basal group Ephedraceae possesses an extremely reduced female cone with only the uppermost pair/whorl being fertile, while both the Gnetaceae and the Welwitschiaceae bear female cones/spikes with multiple whorls of fertile bracts. Here, we describe a new ephedroid macrofossil, Liaoningia decussata Yang et Lin, gen. et sp. nov., from the Lower Cretaceous Yixian Formation of western Liaoning in China. This species has typical ephedroid morphology, e.g. the dichasial branching shoot system, swollen nodes, internodes having many fine longitudinal striations, and decussate phyllotaxy, lengthy linear leaves possessing two parallel veins, and female cones consisting of paired bracts. This new genus is similar to the Ephedraceae in its vegetative organs, but differs from the latter by the female spikes with multiple pairs of fertile bracts. In this respect Liaoningia is similar to both the Gnetaceae and the Welwitschiaceae, but distinctly differs from the latter two genera in its vegetative organs. As a result, our new genus shows intermediate morphology between the Ephedaceae and the other two families of the gnetophytes, and is probably a missing link in the evolutionary process from the Ephedraceae to the clade including the Gnetaceae and the Welwitschiaceae. |
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| Keywords: | Early Cretaceous Evolution Female spike Gnetophytes Yixian formation |
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