• 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.34 no.5
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• pp.402-406
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• 2013

Since 1984, the author has been studying the Daedong flora and has collected a large number of fossil plants from the Amisan Formation of Nampo Group distributed in Chungnam Coal-Field. One of the fossil plants was bennettitalean male flower, which was collected in 1986. The author described it as Weltrichia sp. The occurrence of Weltrichia sp. is the first record in the Early Mesozoic Daedong flora of Korea.

• Journal of the Korean earth science society
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• v.31 no.5
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• pp.430-436
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• 2010

Some materials belonging to the Leptostrobus myeongamensis Kim were found in the Upper Triassic Amisan Formation, Nampo Group, Korea. This species is closely associated with the foliage of Czekanowskia ex gr. rigida Heer. Although none of Leptostrobus myeongamensis Kim has been found in organic connection with Czekanowskia leaves, it is considered that they belong to the same taxa based on their common occurrence. The occurrence of Leptostrobus myeongamensis Kim from the Late Triassic floras of Korea is one of the oldest records in the Mesozoic floras found in the world.

• Journal of the Korean earth science society
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• v.22 no.2
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• pp.105-111
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• 2001

Seven specimens of raindrop imprints are discovered from the Late Triassic Amisan Formation of Nampo Group distributed in the Myeongam area of Boryeong-City, Chungcheongnam-do. The raindrop imprints are interpreted to had been formed in lacustrine environments under subtropical humid climate during the lowered period of the surface of the water by temporally or seasonally arid climate. The raindrop imprints are the first finding in the Lower MesozoicNampo Group, Korea.

• Journal of the Korean earth science society
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• v.23 no.1
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• pp.30-37
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• 2002

Leptostrobus myeongamensis sp. nov. is newly described from the well-preserved but broken material occurring in the Upper Triassic Amisan Formation of the Nampo Group in Korea. This species is characterized by its lateral appendages of cone axis, each consisting of a rounded capsule and small scale leaf, and by its cone base covered with small scale leaves, the same size as in cone axis. This species is the first record from the Mesozoic strata in Korea.

• Journal of the Korean earth science society
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• v.25 no.1
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• pp.32-38
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• 2004

Some fine specimens of Annulariopsis bunkeiensis were collected from two fossil sites of the Amisan Formation of Nampo Group distributed in the Jogaegol, Boryeng City, Chungnam Province. According to our detailed study from our new material, the leaves of A. bunkeiensis are not mucronate, but emarginate at their apices. Accordingly, we revised the diagnostic characters given by Kimura and Kim (1988) mainly in regard to the leaf apex.

• Journal of the Korean earth science society
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• v.29 no.6
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• pp.466-473
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• 2008

This study deals with the morphological characteristics and structure of organ fossils of Neocalamites carrerei such as rhizomes, aerial leafy stems, and cones collected in situ from the Amisan Formation of Nampo Group. Judging from the size of some extant Equisetum and paleoclimate of Daedong flora, it is considered that the size of Neocalamites carrerei was probably very large. The cone of Neocalamites takahashii (Kon'no) is closely associated with the leaves of Neocalamites carrerei. It indicates that two organ fossils mentioned above probably belong to the same species. Comparing with very abundant occurrence of aerial leafy stems and rhizomes in the Amisan Formation, cones are very rare. This fact implies that Neocalamites reproduce not only by spore reproduction, but also by asexual reproduction. Neocalamites largely differ in the leaf form and size from Equisetum.

• 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.

• Journal of the Korean earth science society
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• v.35 no.3
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• pp.161-167
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• 2014

Recently, a winged insect fossil the Mecoptera has been discovered for the first time in the Late Triassic Amisan Formation in the Boryeong area, Chungnam, Korea. The fossil is classified as Mesopsyche dobrokhotovae based on the characteristics of wing venation. Insect fossils which belong to this Genus show worldwide distribution in the Late Triassic, making it possible to estimate that they thrived in this period. Extant Mecoptera survive in humid environments by hanging onto tree leaves or stems and eating other small insects. Compared to the ecology of extant Mecoptera, the presence of the fossil Mecoptera indicates that the paleoenvironment in Nampo Group was very similar to the present during the Late Triassic Period. Mesopsyche dobrokhotovae is the first Mecoptera occurrence and one of the oldest insect fossil occurrences in Korea.

• 한국지구과학회:학술대회논문집
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• 2003.09a
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• pp.69-70
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• 2003