| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2001: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
In the fiscal year of 2002, 1 carried out a field collection trip to Hokkaido, where a large number of nodules containing plant fragments were collected. Since there were few material that can fit the purpose of this study, I continued taxonomic identification of a previously collected fructification of possible gymnosperm, and further search of fossil fungi and arthropods in the fossil plant tissue. Although I could not find any fungi nor arthropods, the fructification itself was identified as a new species of gymnosperm that can be assigned to a new order. A fossil tree fern rhizome donated from an amateur collector was designated as a new species of the Cyatheaceae, which is attributable to the genus Dicksonia. Both new taxa will be described elsewhere.
I have continued microscopical search of fossil fungi in permineralized fossils, mainly woods, collected from the Cretaceous of Goshonoura Series, Kumamoto Pref., Sebayashi Series, Gunma Pref., Kuji and Taneichi Series, Iwate Pref., a
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nd Yezo Group, Hokkaido. Wood decaying fungi were commonly found in disorganizing tissues. This shows wide activity of wood decaying fungi in the Cretaceous terrestrial ecosystem. Also found important was the predominant occurrence of VA (vesicular-arbuscular) mycorrhizae in the root cortical layer of a Cretaceous tree-fern Tempskya. The VA mycorrhizae were absent in the root system of any Cyatheaceous ferns, which also exhibit a tree habit. It is likely that mutualistic VA mycorrhizae made Tempskya possible to effectively absorb inorganic materials. Collapse of this mutualistic relationship might have causec extinction of Tempskya by the end of the Cretaceous.
Search of arthropods in permineralized fossils from Hokkaido resulted in findings of 3 different insects in two different organs. One insect was found in a gymnosperm fructification, and was attributed to the Psocoptera. Other two existed in a deformed tissue of a gymnospermn twig, which is a possible insect gall. One is a poorly preserved larva hard to taxonomically identify, and the other is a small adult that nested in a round sturucture probably made by itself. The adult form was comparable to the Staphilinoidea of Polyphaga. The findings provided evidence of varying ways of use of plant tissues by insects in the Cretaceous ecosystem. Less
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