Ctenodactyloid rodent assemblage from Kargil Formation, Ladakh Molasse Group: age and palaeobiogeographic implications for the Indian subcontinent in the Oligo-Miocene

Abstract

Two ctenodactyloid rodents, Fallomus razae Flynn, Jacobs & Cheema and F. ladakhensis nov. sp., arebeing described from the Kargil Formation of the Ladakh Molasse Group of Kargil area. Fallomus (? Chapattimyidae) is considered an endemic offshoot of the South Asian Eocene ctenodactyloid stock. The new species is relatively larger and more hypsodont with an ectostylid borne on a separate pillar. At Kargil, Iberomeryx (= Cryptomeryx) savagei and Lophiomeryx kargilensis were earlier reported and indicate an Upper Oligocene age for the lower part of the Ladakh Molasse Group. Both these taxa show Eurasian affinity. From the upper part of the Ladakh Molasse Group i. e. Pashkyum Formation, Hyoboops palaeindicus is known and indicates a Lower Miocene age for the lower part of the Pashkyum Formation. The fossil vertebrates suggest an age for the Ladakh Molasse Group extending from Upper Oligocene to Middle Miocene. The incisor enamel ultrastructure of Fallomus is multiserial with average inclination of the Hunter Schreger Bands varying between 30°-35°