2023/12/08
Keio University
Hiroaki Aiba, a teacher at Keio Yochisha Elementary School, and Dr. David Král of Charles University in the Czech Republic have reported a 300,000-year-old fossil of the family Geotrupidae (earth-boring dung beetles) as a new species. The fossil was discovered in September 2022 by Kota Yatagai, then a third-year student at Keio Senior High School, when he broke open a rock during a science class. The rock was provided as teaching material by the Konoha Fossil Museum in Nasushiobara, Tochigi Prefecture, and was excavated from the 300,000-year-old Middle Pleistocene Shiobara Group strata distributed on its grounds. The discovered fossil measures approximately 25 mm in total length and is almost perfectly preserved. It belongs to the family Geotrupidae, and features such as its large mandibles indicate that it is a member of the genus Ceratophyus .
While most insect fossils from the Quaternary Pleistocene (300,000 years ago) have been considered to be of extant species, this fossil is an extinct species. This is the world's first new species of Geotrupidae fossil from the post-Pliocene era, making it the world's most recent extinct fossil species. Furthermore, since this group of insects feeds on the dung of herbivorous mammals, there is also the mystery of which animals' dung it fed on at that time. Therefore, this discovery has the potential to be a valuable resource for considering the speciation and biogeography of insects in the Japanese archipelago.
The results of this research were published online on November 30, 2023, in Paleontological Research , the international journal of the Palaeontological Society of Japan.
Please see below for the full press release.