Palaeoecology of the mid-Cretaceous siphonate bivalve genus Goshoraia (Mollusca, Veneridae) from Japan

摘要

The mid-Cretaceous bivalve Goshoraia Tamura, 1977, endemic to Japan, is an early example of shallow-marine siphonate bivalves of the family Veneridae Rafinesque, 1815. Three species, including one new, are here described: Goshoraia minor Tashiro and Kozai, 1989 (Aptian), G. crenulata (Matsumoto, 1938; Albian-lower Cenomanian) and G. maedai sp. nov. (middle to upper Cenomanian). The habitats of Goshoraia have been extensively compared with those of common Cretaceous, nonsiphonate burrowers, such as trigoniids, which range from tidal flat and shoreface to shelf environments. Depth of burial, which can be estimated from the extent of the pallial sinus, increases from the ancestral G. minor to its descendants G. crenulata and G. maedai sp. nov., documenting that the ability to burrow within this genus improved in time. These morphological and palaeoecological changes may be related to the Mesozoic marine revolution during the mid-Cretaceous.