Venezuelan tarpit fossils shed new light on great megafaunal exchange
Tarpits are areas where bituminous crude oil emerges onto the Earth’s surface as it leaks out of the reservoirs below, and have been used as an indicator for seeking oil deposits. Their most interesting feature however is that they are perfect animal traps, and the tar acts as an excellent preservative for any animal who strays too far into the black gooey mass. The sampling of ancient ecosystems is relatively complete, ranging from mammoths to insects, pollen or seeds and man-made arrowheads from ancient hunter gathering denizens of the area. The most famous ones are the La Brea pits just outside Los Angeles in California (see http://tinyurl.com/nklvhh3)
The Mene de Inciarte tarpit in the Sierras de Perija on the Colombian border provides an excellent comparison to the fauna found at La Brea, giving us insights into how the fauna in the southern half of the continent differed from that in the north. The comparison also tells us how the faunas of the two continents mixed when they were joined together by the slow ballet of continental drift, a mere 2-3 million or so years ago. A single cubic metre, carefully excavated, disgorged over 16,000 specimens of ancient life, some of which are helping rewrite the timing of the waves of exchange of life forms between the Americas.
The finds include a mastodon femur, and remains of a glyptodont (giant sloth, depicted in the photo), a 3 metre pelican, a caiman the size of a bus and most significantly the skull of a sabre toothed tiger named Homotherium venezuelensis. This last find was over a million years older than any found so far in South America, forcing a re assessment of the timing of the 7 or more waves of megafaunal exchange. This latest discovery adds a new wave to the American biotic exchange that accompanied the joining of the two continents. The arrowheads also suggest hunting in the southern part of America may have begun earlier than thought, though this will prove contentious among archaeologists who are still debating the evidence of earlier humans than the Clovis culture in the Americas, and is being researched further. The team are now actively searching for human remains to date.
Loz
Image credit: Juan Barreto/AFP/Getty Images
http://www.theguardian.com/world/2013/oct/30/venezuelan-fossils-ice-age-sabre-toothed-tiger
http://www.iol.co.za/scitech/science/discovery/venezuela-s-jurassic-park-1.1574026#.UnQdwBDYO4w
http://phys.org/news/2013-09-oil-emerges-venezuela-jurassic.html
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