The biogeographic and tectonic history of India

Abstract Aim To present an up to date account of the Mesozoic history of India and its rela-tionship to the other Gondwana continents and to Eurasia.Location Continents surrounding the Western Indian Ocean.Methods Utilization of recent evidence of continental relationships based upon researchin stratigraphy, palaeomagnetism, palaeontology, and contemporary biotas.Results The physical data revealed a sequence of events as India moved northward: (1)India–Madagascar rifted from east Africa 158–160 Ma (million years ago), (2) India–Madagascar from Antarctica c. 130 Ma, (3) India–Seychelles from Madagascar84–96 Ma, (4) India from Seychelles 65 Ma, (5) India began collision with Eurasia 55–65 Ma and (6) ﬁnal suturing took place c. 42–55 Ma. However, data from fossil andcontemporary faunas indicate that, throughout the late Cretaceous, India maintainedexchanges with adjacent lands. There is an absence in the fossil record of peculiaranimals and plants that should have evolved, had India undergone an extended period ofisolation just before its contact with Eurasia.Main conclusions The depiction of India in late Cretaceous as an isolated continent is inerror. Most global palaeomaps, including the most recent one, show India, as it movesnorthward, following a track far out in the Indian Ocean. But the evidence now indicatesthat India’s journey into northern latitudes cannot have taken place under such isolatedcircumstances. Although real breaks among the lands were indicated by the physicaldata, faunal links were maintained by vagile animals that were able to surmount minormarine barriers. India, during its northward journey, remained close to Africa andMadagascar even as it began to contact Eurasia.KeywordsIndia, biogeography, Gondwana, late Cretaceous, palaeontology, tectonics.INTRODUCTIONIt has now been more than 40 years since the theory of platetectonics has found general acceptance and more than30 years since Dietz & Holden (1970) published their mapsillustrating the breakup of Pangea and the dispersal of con-tinents through time. Although many palaeomaps by variousauthors have been published since 1970, the predominantmodern series is that produced by the Palaeomap Project atthe University of Texas (Arlington). The latest edition enti-tled ‘Atlas of Earth History’ (Scotese, 2001) is a beautiful,colour rendition with artistic representations of sea ﬂoor,shorelines, and mountains.The Palaeomap Project produces a variety of educationalmaterials including a CD ROM map series with computeranimations and Palaeo-Globe kits for constructing physicalmodels of the earth at different periods of time. The Projecthas a web site advertising its products (http://www.scote-se.com) and offers special discounts to primary and secon-dary schools. On one hand, there is no doubt that thisproject performs an important educational service providingan attractive introduction to plate tectonics for a broadaudience; on the other hand, it must be asked if the maps andvirtual reality simulations are accurate representations ofcurrent scientiﬁc knowledge. The information is presented ina factual manner with no indication that some of it may notbe on ﬁrm ground.In the case of India, the Project supplies a virtual realitysequence in which that continent is shown as separatingfrom Madagascar 90 Ma, moving through the middle of the