九州唐津炭田産の大型アミノドン類と始新世・漸新世境界

概要

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A right maxillary fragment with M^<2-3> of a large amynodontid was found from the middle member of the Yoshinotani Formation of the Ochi Group at Tatsukawa Colliery of the Karatsu Coal-field, Kyushu in 1962. It was identified as cf. Zaisanamynodon borisovi, within the family Amynodontidae, based mainly on its large size and lower crowned molars. Z. borisovi is characteristic of Ergilian age of the Asian land mammal scheme. The Eocene-Oligocene boundary was recently redefined and correlated at 34 Ma in absolute age. The Ergilian land mammal age is currently placed in late Eocene. There has been controversy concernin the locations of the Eocene-Oligocene boundary within the Ochi and Kishima Groups in the Karatsu Coal-field. The presence of cf. Z. borisovi in the Yoshinotani Formation and a fission track age (34.6Ma) obtained from the same formation support the correlation of the Eocene-Oligocene boundary with the boundary between the Ochi and Kishima Groups.
国立科学博物館の論文
1996-12-22