Estheriid zonation in the Gondwana

Abstract

Estheriid fauna of the Indian Gondwana is represented by 18 genera of fossil conchostraca. On the basis of recent discoveries of leaiid estheriids from the Lower Gondwana formations four new biozones are added to the previously established horizons. Nine esteriid biozones are now established for the entire Gondwana sequence of India. Lacuna, however, still exists in some of the formations. The biozones proposed are helpful for basinal correlation. There are some excellent index fossils to distinguish the Late Permian and Early Triassic Gondwana sediments and emplace precisely the boundary between them. With the record of Leaiid estheriids emerging from the Indian subcontinent, for the first time, all the five continents of the Gondwanaland can be tied up, solving a long existing problem in understanding the migratory route of the fauna. Indian fauna bears many of the common elements of the Gondwana estheriids of other continents from Late Permian to Jurassic periods. Estheriellids are confined to India (Early Triassic), Africa (Late Triassic) and South America (Jurassic-Cretaceous) only. The Indian species of Estheriells bear closer affinity to those of Europe (Bundenstein, Germany). It suggests dispersal of the bioprogram through land connections between the two super-continents during the Early Triassic.