Reconstruction of a river delta in northwest Venezuela 9 million years ago. Fossils uncovered in the Urumaco Formation show the delta was home to a wide variety of animals, many of whom were giants, such as sloths, rodents, armadlillos and crocodiles of immense proportions. All of the land animals found so far disocvered in the Urumaco have a south American affinity demonstrating no land bridge with North America at this time. Only later, after three million years ago when the land bridge formed did the Great American Biotic Interchange take place.
Image: Jorge Gonzalez