• Journal of the Korean earth science society
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• v.36 no.2
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• pp.181-189
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• 2015

A large number of fossil conchostraca used in this study were collected from the Amisan Formation distributed in the western part of Chungnam, Korea. These fossils were densely discovered in several horizons of the Amisan Formation, and might have flourished in the fresh water environment of subtropical climate. The fossil conchostraca from the Amisan Formation were classified into four species belonging to three genera as follows: Euestheria kawasakii, E. shimamurai, Sphaerestheria koreanica, and Cyclestherioides rampoensis. Out of four species, the last species was previously described from the Amisan Formation, and the other three species were newly found. Based on the fossil conchostraca, it is inferred that the geological age of the Amisan Formation falls under the Late Triassic Period.

• Journal of the Korean earth science society
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• v.38 no.4
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• pp.293-302
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• 2017

A large number of stonefly nymph fossils were discovered from the Late Triassic Amisan Formation in the Boryeong region, Korea. These Plecoptera were classified as Platyperlidae, Baleyopterygidae, and Siberioperlidae based on their external morphologies. The Baleyopterygidae were most abundant among the fossils. This suggests that the plecopteran has already been widely distributed in the Northeast Asian region including Russia, Mongolia and China during the Mesozoic. The fossils of these stoneflies imply that benthic habitats of flowing and fresh waters may have existed, given the fact that they are similar with the biology of extant species. These Plecoptera were found together with Ephemeroptera and Conchostraca and thus, they were presumed to be preying on these insects.