Bulletin of the Mizunami Fossil Museum No. 3
Brachiopoda fauna of the Miocene Mizunami group, central Japan
- BMFM03-005Itoigawa et al.,1976（PDF 5.80MB）
Itoigawa et al. (1976a) print-version
Published: 1976/12/25 Page: 41–54, pls. 12–15
Miocene Brachiopoda fossils of the Mizunami group from 24 localities in the Mizunami and Iwamura basins are studied. Twelve species are recognized in them as shown in Table 1 and described in detail. It is concluded that the Brachiopoda fauna has characteristics as follows; 1. Brachiopoda fossils are not so abundant as mollusks in the Mizunami group. 2. They occur in specific horizons and localities as Inkyoyama (1) and Nanamagari (3) of the Kujiri fades, many localities of the Nataki conglomerate member and Higashihora (22) of the Kubohara member in the Iwamura basin. 3. Many of fossil specimens show allochthonous occurrences in conglomerates, sandstones and nodules. 4. Many immature speimens are recognized in some localities. Examples are “Dallinella” in the Kujiri facies, Coptothyris in the Nataki member, and Terebratalia in the Shukunohora fades and the Kubohara member of the Toyama formation. 5. Brachiopoda fossils commonly cooccur with Bryozoa specimens. 6. Individual variation is common in some specimens. It is found in features as shell shape and number of ribs. Relationship in the Brachiopoda fauna and paleoenvironmental condition is shortly discussed and is shown in Table 2. Brachiopoda assemblages in some beds are synthesized as follows; Kujiri facies “Dallinella” -Discinisca assemblage Shukunohora facies Terebratalia -Discinisca assemblage Nataki member (except St. 288 -Loc. no. 21) Coptothyris-Terebratulina assemblage Nataki member (St. 288) Terebratulina-Coptothyris assemblage Oidawara member Laqueus assemblage Kubohara member Terebratalia-Discinisca assemblage