THE BIOGEOGRAPHICAL HISTORY OF CINGULATA (MAMMALIA, XENARTHRA) AND THE GREAT AMERICAN BIOTIC INTERCHANGE (GABI)

CARLINI, A. A; ZURITA, A. E

Mendoza

Congreso; 10 th International Mammalogical Congress; 2009

CONICET-SAREM

The latest finds from northern South America, have brought about a new interpretation of the evolutionary and biogeographical history of the major groups of Cingulates on and around the GABI. This can be summarized in the following points: 1) unfortunately, there are still only poor records of dasypodids in the Pliocene of Northern South America, but the first remains of Propraopus have been exhumed from San Gregorio Formation (late? Pliocene), Venezuela; 2) morphological evidence suggests that the glyptodonts from the middle Miocene-Pliocene of northernmost South America (Colombia and Venezuela) do not belong to Propalaehoplophorinae, but actually represent the first stages in the cladogenesis and later dispersion of the Glyptodontinae, and they represent the oldest records for this subfamily. So, the Propalaehoplophorinae were restricted to southernmost South America; 3) the oldest records of Glyptodontinae in southernmost South America (latest Miocene and Pliocene), and partially coincide with the peak of the "age of southern plains", that could have acted as a "biogeographical corridor"; 4) during the Pliocene, the glyptodontines (probably together with the "glyptatelines") passed onto Central and North America. At present, Glyptotherium and Pachyarmatherium are the only genera recognized in those areas; 5) the presence of Glyptotherium and Pachyarmatherium in the latest Pleistocene of Venezuela suggests a re-entry into South America at some point during the late Pleistocene, probably associated with "biogeographical corridors" formed during glacial periods; 6) a similar bidirectional migratory pattern has been observed for the pampatheriids, they migrated into Central and North America. Later, this clade re-entered into South America, following two alternative routes, one "para-Andean", and another parallel to the eastern coast. The cyclical climatic-environmental fluctuations occurred during the Pleistocene would have triggered speciation processes that gave rise to endemic South American species.