Antarctic belemnite biogeography and the break-up of Gondwana

Abstract

Abstract In the late Jurassic, the belemnite genera Hibolithes and Belemnopsis were abundant and widespread in Tethys, characterizing a Tethyan Realm that extended south from southern Europe and Asia to Antarctica and the rest of Gondwana. Although a distinct Southern Hemisphere ‘Austral’ belemnite realm counterbalancing the northern Boreal Realm was absent, it is clear that a significant degree of endemicity existed at the species level, with distinct species groups in Indonesia, Madagascar, Australasia, South America and so on. Trans-Gondwanan faunal links first developed in the late Jurassic shelf seaway between Antarctica, Madagascar and India. Belemnopsis became extinct in southern Europe, and was left as a relict, endemic to this trans-Gondwanan seaway. In the Aptian the Belemnopseidae were eventually replaced around Gondwana by the endemic family Dimitobelidae, which developed as the Antarctic—Australasian core of Gondwana began to drift south. In Tethys few genera remained, the Tethyan Realm finally breaking down in the late Cretaceous. Initially the Dimitobelidae were widespread in Gondwanan seas, the trans-Gondwanan links developed in the Jurassic being maintained. However, as Gondwana fragmented further in the late Cretaceous, these links broke down and the Dimitobelidae survived only in the Antarctic-Australasian region which was retreating southwards.