Australobuchia Zakharov, 1981

Fuersich, Franz T., Alberti, Matthias, Pandey, Dhirendra K. & Ayoub-Hannaa, Wagih S., 2022, Jurassic bivalves from the Spiti area of the Himalayas, northern India, Zitteliana 96, pp. 153-178 : 153

Genus Australobuchia Zakharov, 1981

Type species.

Aucella plicata Zittel, 1864.

Remarks.

The generic assignment of the two species described below is still under discussion. Most recent authors (e.g., Crame 1990; Hikuroa and Grant-Mackie 2008) follow Zakharov (1981), who regarded buchiids from high latitudes of the southern hemisphere as belonging to a different lineage than those from the northern hemisphere and therefore included them in his new genus Australobuchia . Other authors (e.g., Crame 1986, 1993) argue that more research is needed to understand the origin and evolution of the bipolar benthic faunas, which may have resulted from fragmentation of an originally wide distribution or by dispersal. The Spiti area at the northern margin of the Indian craton bordering the Neotethys during the Late Jurassic occupied a southern palaeolatitude between 20-30° according to the Paleolatitude Calculator of van Hinsbergen et al. (2015). The occurrence of high latitude southern taxa at relatively low latitudes can be explained by their restriction to outer shelf and slope environments where, due to upwelling, lower water temperatures prevailed (compare Alberti et al. 2021; Fürsich et al. 2021). In this context, isothermal submergence may explain the way polar faunas were able to cross the tropics (e.g., Crame 1993).