Snakes from the Paleocene and Eocene of Patagonia (Argentina): Paleoecology and coevolution with mammals

Snakes from the Paleocene (? Madtsoia sp.) and Eocene (? Madtsoia sp., ? Boa sp., Chubutophis grandis gen. et sp. nov., Boinae indet.) of Patagonia, Argentina, are reviewed. The Late Cretaceous and Early Tertiary records are analysed and compared. The conclusions are: (1) The Dinilysiidae do not reach the Tertiary. (2) The Boidae seem to have had a basic diversification in Gondwana during the Cretaceous. (3) The snakes from the Late Paleocene were larger than those of the Late Cretaceous, probably due to the more varied and abundant mammals of larger size providing their most frequent prey. (4) During the Early Eocene a greater ecological diversity of snake faunas is present. It probably represents the existence of environmental “patches”; or “pulses”; in subtropical general areas and the existence of a more varied mammalian fauna. (5) As conclusion, during the Early Tertiary of Patagonia the snakes were the most important predators together with ziphodont crocodiles, phorusrhacoid birds and borhyaenid mammals. The evolution and diversity of these snakes seems to have been in accordance with the basic South American mammalian diversification and the greater ecological and size diversity of the herbivorous mammals (co‐evolution) at the same time.