Kerguelen plateau and the late cretaceous southern-continent bioconnection hypothesis: Tales from a topographical ocean

Abstract

Aim To evaluate rigorously an influential palaeobiogeographical hypothesis which states that in the Late Cretaceous (until c. 80 Ma) the Kerguelen Plateau provided a terrestrial causeway between East Antarctica and India that, in turn, formed part of a longer overland route between South America and Madagascar. Location Southern Ocean, Indian Ocean, East Antarctica, India and Madagascar. Methods Palaeogeographical modelling drawing on geological and geophysical data, bathymetric charts and plate tectonic reconstructions. Results During the Late Cretaceous, only small portions of the present-day Kerguelen Plateau were sub-aerial. Additionally, the plateau's north-north-west and south-south-east ends did not directly abut India and Antarctica, but instead were separated by large gaps. Thus, the notion that the two continents were then linked by a land route running the entire length of the edifice is almost certainly incorrect. Main conclusions The currently available physical evidence indicates that the Late Cretaceous southern-continent connection hypothesis, which is based exclusively on biological data, is untenable. Assuming the fossil and/or extant biological records of Madagascar-India are closely related to those of South America, alternative palaeogeographical scenarios need to be explored to explain this conundrum. Overwater dispersal and/or an alternative passage involving a more direct route via Africa (with crossings of the Mozambique Channel and a then appreciably narrower Central Atlantic) should be considered. © 2009 Blackwell Publishing Ltd.