Permalink : http://hdl.handle.net/2115/38455

KEYWORDS : Gall fossil;Plant - insect coevolution;Resistant macromolecule (polymer);Aphid (Aphidoidea)

Pyrolytic analysis was performed on a leaf fossil, containing a gall-like spherule structure, from the Eocene Ikushunbetsu Formation in the Yubari area, Hokkaido, Japan, in order to examine the potential and applicability of the geochemical methods for identification of the trace fossils of insects such as gall. Several compounds such as n-alkanes and alkyl benzenes and naphthalenes were detected in leaf blade sample, whereas they were absent in the spherule sample. These results indicate that the gall-like spherule in the leaf fossil is neither an organic fossil nor a gall. However, as organic molecules could be detected in a small amount of leaf sample, the method used has potential to identify organic fossil originated from gall. Combination of morphological and geochemical studies on the gall fossils is suggested to provide essential information for understanding coevolutionary relationships between terrestrial higher plants and insects, at geologic time scale, as well as macroevolutionary patterns in plant - insect associations.