Tsuga shimokawaensis,a new species of permineralized conifer leaves from the Middle Miocene Shimokawa Group,Hokkaido, Japan |
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Authors: | Midori Matsumoto Takeshi Ohsawa Makoto Nishida |
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Institution: | (1) Department of Earth Sciences, Faculty of Science, Chiba University, 263 Chiba, Japan;(2) Laboratory of Phylogenetic Botany, Faculty of Science, Chiba University, 263 Chiba, Japan;(3) Research Institute of Evolutionary Biology, 158 Tokyo, Japan |
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Abstract: | Silicified pinaceous leaves from the late Middle Miocene bed of Shimokawa Town, central Hokkaido, Japan are described asTsuga shimokawaensis sp. nov. Comparisons with leaves of extant species ofTsuga show that the new species is assigned to sect.Tsuga, resembling the extant speciesT. heterophylla in having usually one-cell-layered hypodermis, andT. sieboldii in having mesophyll cells between the resin canal and the hypodermis. From cladistic analyses we infer thatTsuga shimokawaensis is positioned the basal in sect.Tsuga and that sect.Tsuga comprises four species groups. |
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Keywords: | Fossil leaf Middle Miocene Pinaceae Tsuga shimokawaensis |
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