[B-PT05] 化学合成生態系の進化をめぐって

[BPT05-P04] New species of the Jurassic to Cretaceous seep-restricted bivalve Caspiconcha from Japan, Spain and New Zealand

*ジェンキンズ ロバート¹、Kaim Andrzej²、疋田 吉識³、Kiel Steffen⁴ (1.金沢大学理工研究域自然システム学系、2.ポーランド古生物学研究所、3.中川町エコミュージアム、4.スウェーデン自然史博物館)

キーワード：二枚貝、メタン湧水、分類

Chemosynthesis-based ecosystems are commonly found around hydrothermal vents and methane seeps in the deep sea. Mesozoic vents and seeps were also inhabited by animals endemic to such environments. Amongst bivalves, several genera of Lucinidae and the large kalenterid genus Caspiconcha were restricted to the Mesozoic seeps. Thus, it is important to know their fossil record to understand evolutionary history of chemosynthetic communities.

We report four new species of the Mesozoic methane seep-restricted bivalve genus Caspiconcha. One is from the late Albian of northern Spain. Two new species are from the late Albian of Yubari City, Hokkaido, and from the Campanian of Nakagawa Town, Hokkaido, respectively. The other is from the late Albian to mid-Cenomanian of New Zealand. The oldest confirmed record of the genus is known from the latest Jurassic, it reached its maximum diversity in the Albian, and declined in diversity and abundance through the Late Cretaceous.