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Fossils of 3 new prehistoric cockroach species found in central Japan's Fukui Pref.

This image provided by the Fukui Prefectural Dinosaur Museum shows a fossilized Petropterix fukuiensis wing.

KATSUYAMA, Fukui -- Fossils belonging to three previously undiscovered prehistoric cockroach species have been found in an around 120-million-year-old stratum in this central Japan city, the Fukui Prefectural Dinosaur Museum announced at a Sept. 27 news conference.

    The fossils were unearthed in a Lower Cretaceous stratum called the Kitadani Formation of the Tetori Group in the city's Kitadanicho district. A museum representative said, "This is the first time that multiple cockroach species have been found in the same spot in a Cretaceous stratum in Japan. They will be important fossils in studying cockroaches' evolution in the Northern Hemisphere at the time."

    Cockroaches are said to be closely related to termites and praying mantises, and the world's oldest fossil of a cockroach was found in a roughly 320-million-year-old Upper Carboniferous stratum. Because they continue to exist to this day, they are called living fossils. The oldest roach fossil excavated in Japan was apparently from an Upper Triassic stratum dating back around 230 million years in Mine, Yamaguchi Prefecture.

    The three new species' fossils were unearthed over 2014 and 2015, and the dinosaur museum, Fukui Prefectural University and Kyushu University jointly studied them. All three are wing fossils, and their shapes and sizes were among the factors that helped identify them as new species. Among them is "Petropterix fukuiensis," which roughly means "fossil of a cockroach representing Fukui Prefecture." It apparently had hard wings like those of a beetle, and its fossilized remains measure 2.45 millimeters by 6.3 millimeters.

    This artist's rendition by Tsukunosuke and provided by Nozomu Oyama shows newly discovered cockroach species.

    A total of five cockroach species -- including the three new ones -- were confirmed in the joint research. All are believed to have lived in the same period as the small theropod dinosaur Fukuivenator and the sauropod dinosaur Fukuititan, the fossils of which were both discovered in Fukui Prefecture.

    "There is a theory Fukuivenators were omnivorous, so they might have chased these newly discovered kinds of cockroaches," said museum researcher Hirokazu Yukawa, who specializes in paleobotany -- the study of ancient plants. "The findings this time get us closer to revealing the ecology and mystery of not just dinosaurs, but also totally different creatures that lived in the same period. We can expect new discoveries in future excavations that bring us closer to understanding the creatures and environment in the age of the dinosaurs."

    Their paper was published in an international academic journal in Germany on Sept. 9.

    (Japanese original by Riki Iwama, Fukui Bureau)

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