Fossils of a dytiscid beetle, Ilybius weymarni, from late Pleistocene Maebashi peat in Maebashi City, Central Japan

Abstract

Abundant fossil insects were obtained from the Maebashi Peat (ca. 14 000-13 000 yrs BP). These are composed of aquatic and marshy insects such as Dytiscidae, Donaciinae, Straphylinidae, and Carabidae. The palaeoenvironment of the Maebashi Pear, based on insect and plant fossils, is as follows: there were mainly marshy areas with Cyperacease, Phragmites, Lysichiton, and Alnus, and scattered areas of shallow water. The marshy area is thought to have been surrounded by needle-leaved forests of Picea, Pinus, and Larix mainly. The paleoclimate was considered to be cooler than at present, since Ilybius weymarni and Hydroporus sp. can be presently found in cooler regions from northern Honshu to Hokkaido.