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A monospecific assemblage of terebratulide brachiopods in the Upper Cretaceous seep deposits of Omagari, Hokkaido, Japan

100%

Kaim A., Bitner M. A., Jenkins R. G., Hikida Y.

Acta Palaeontologica Polonica

2010

tom 55

nr 1

The Campanian (Upper Cretaceous) seep carbonate at Omagari (Hokkaido, Japan) yields a monospecific association of the terebratulide brachiopod Eucalathis methanophila Bitner sp. nov. The association is the only occurrence of brachiopods known from the post−Early Cretaceous history of chemosynthesis−based communities. Unlike many earlier rhynchonellide−dominated hydrocarbon seep associations—which disappeared in Aptian times—this association is composed of chlidonophorid terebratulides. It is hypothesised here that large rhynchonellide brachiopods have been outcompeted from chemosynthesis−based associations by large chemosymbiotic bivalves (especially lucinids) and that this seep association containing numerous terebratulide brachiopods originated as a result of immigration from the background fauna settling in a seep that lacked numerous large bivalves but offered some hard substrates for brachiopod attachment. Some living chlidonophorids are known to settle around seep/vent localities or more generally in deep−water hard−substrate settings. We review occurrences of brachiopods in chemosynthesis−based associations and show that brachiopods immigrated repeatedly to seep/vent environments. Eucalathis methanophila Bitner sp. nov. represents the oldest and single Mesozoic record of the genus. The new species is similar in ornamentation to three living species, Indo−Pacific E. murrayi, eastern Atlantic E. tuberata, and Caribbean E. cubensis but differs in having a higher beak and wider loop. Additionally the studied species is nearly twice as large as E. tuberata.

Gastropods from Late Cretaceous Omagari and Yasukawa hydrocarbon seep deposits in the Nakagawa area, Hokkaido, Japan

100%

Kaim A., Jenkins R. G., Hikida Y.

Acta Palaeontologica Polonica

2009

tom 54

nr 3

463-490

Sixteen gastropod species from two Campanian (Upper Cretaceous) hydrocarbon seep localities in Hokkaido, Japan are described. Seven species are new: the acmaeid limpet Serradonta omagariensis; three turbinids: Homalopoma abeshinaiensis, Cantrainea yasukawensis, and C. omagariensis; the trochid Margarites sasakii; the seguenzioid Cataegis nakagawensis; and the provannid Provanna nakagawensis. The most common species in the investigated localities are acmaeid limpets (S. omagariensis), tiny turbinids (H. abeshinaiensis, C. yasukawensis, C. omagariensis), and provannids/hokkaidoconchids (P. nakagawensis and Hokkaidoconcha hikidai). The Upper Cretaceous associations described here do not resemble Lower Cretaceous associations known from other regions but are composed of species similar to gastropods from Recent hydrocarbon seeps and hydrothermal vents in the Northwestern Pacific. This strongly suggest that this region possesses a regional pool of gastropods in chemosynthesis−based communities at least since Late Cretaceous time. The only group of gastropods described here which has no Recent counterpart is the Hokkaidoconchidae. A comparison to gastropods from plesiosaur falls and sunken wood of the same age and region strongly suggest that these invertebrate communities do not differ significantly from the coeval hydrocarbon seep communities described herein.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Hikida Y.

2 Jenkins R. G.

2 Kaim A.

1 Bitner M. A.

1 2010

1 2009

Wyniki wyszukiwania

A monospecific assemblage of terebratulide brachiopods in the Upper Cretaceous seep deposits of Omagari, Hokkaido, Japan

Gastropods from Late Cretaceous Omagari and Yasukawa hydrocarbon seep deposits in the Nakagawa area, Hokkaido, Japan