NEOTROPICAL VERTEBRATE FAUNA FROM THE NEOGENE OF LA GUAJIRA, COLOMBIA

An extensive fieldwork has been done in the past three years in the northern part of La Guajira Peninsula, the northernmost region of South America. Herein, we present new records of a very diverse Neotropical vertebrate fauna from the Castilletes (early to middle Miocene) and Ware (Pliocene) Formations. The predominant deposits of these Formations are shallow marine environments, and fluvio-deltaic environments with large freshwater reservoirs that strongly contrast with the dry climate and xerophytic vegetation of La Guajira peninsula today. The most relevant paleontological findings from marine environments are numerous morphospecies of sharks, rays and catfish; while from fluvio-deltaic environments are dogtooth tetras and piranhas (today only distributed in distant areas like the Amazon and Orinoco basins) fresh water turtles, snakes and one of the oldest records of Crocodylus in the Americas. Additionally, the mammal assemblage comprises Xenarthrans that includes Megatheriid and nothrotheriid sloths and the cingulates, Glyptodontinae and Pampatheriidae. Rodents are represented by Chapalmatherium, cf. Neoepiblema and Paramyocastor. Indigenous South American ungulates include horse-like protherotheriids, rhino-like toxodonts and astrapotheres. North American migrants include deer-like Protoceratidae and raccoon-like Procyonidae.

The wide fossil record from La Guajira peninsula provides essential information to understand biological aspects like the evolution and biogeography of the Neogene fauna of America. Also, geological aspects like the formation of Panama isthmus and the rise of the Andes cordillera; and local ecological aspects like changes in the level of the sea and recent desertification events.