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Paleobotanical Section

Hao, Shougang [1], Wang, Deming [1], Wang, Qi [2], Xue, Jinzhuang [1].

Estinnophyton discovered from the Lower Devonian Posongchong Formation of southeastern Yunnan, China: its phylogenetic and palaeophytogeographical significance.

A new species of early land vascular plants, Estinnophyton yunnanense, has been described from the Lower Devonian (Pragian) Posongchong Formation of Wenshan District of Yunnan Province, China. This plant possesses aerial stems with isotomous branching. The leaves are slender, once or twice-bifurcated, arranged in low spirals or pseudowhorls. Fertile leaves are morphologically identical to the vegetative ones, clustered on the axis, forming a loose strobilus-like structure. There are 3-6 fertile leaves in each gyre. Two ovoid-elongate sporangia are singly attached to the adaxial surface each subtended by a recurved stalk, either at the base of each segment in a once-bifurcate fertile leaf or below the points of successive divisions in a twice-bifurcate fertile leaf. E. yunnanense differs from other species described previously from Europe, i.e. E. gracile and E. wahnbachense, mainly in possessing two single stalked sporangia on each fertile leaf rather than two pairs of sporangia, as well as in the dimensions of leaves. In view of the complex taxonomy and nomenclature surrounding the type material of Estinnophyton, we considered possible emendation of the generic diagnosis based on the new Chinese material. Following comparison with members in the Protolepidodendrales and others, Estinnophyton is considered to have had a closer affinity with primitive sphenopsids than the protolepidodendralean lycopsids. The discovery of Estinnophyton yunnanense in China, to a certain extent, reduces the distance between South China (the northeastern Gondwana phytogeographic unit) and Western Europe (Laurussia phytogeographic unit).


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1 - Peking University, Department of Geology, Beijing, 100871, China
2 - Chinese Academy of Sciences, Institute of Botany, Cas, The Center Of Systematic And Evolutionary Botany, 20 Nanxincun, Xiangshan, Beijing, 100093, China

Keywords:
Estinnophyton yunnanense
Lower Devonian Posongchong Flora
sphenopsid.

Presentation Type: Poster
Session: 33-65
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:31


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