[B-PT05] Evolution of Chemosynthetic Ecosystem in Earth History

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

*Robert Jenkins¹, Andrzej Kaim², Yoshinori Hikida³, Steffen Kiel⁴ (1.School of Natural System, College of Science and Engineering, Kanazawa University, Japan, 2.Institute of Paleobiology, Polish Academy of Sciences, Poland, 3.Nakagawa Museum of Natural History, Japan, 4.Swedish Museum of Natural History, Department of Palaeobiology, Sweden)

Keywords:Bivalve, Cold-seep, Taxonomy

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.