Floating Islands

I am taking a Primate Behavior and Ecology course this semester, which has so far been really interesting. I am learning about the differences between apes and monkeys and all that jazz. New World monkeys or platyrrhines diverged from Old World monkeys about 35 mya, but South America split off of Africa much earlier around 100 mya. The earliest fossils were established 26 mya in the New World probably because fossils do not form as well in wet, tropical climates. The real question is: How did the platyrrhines get to South America? The best supported hypothesis is by rafting across on islands of floating vegetation.

A study by Alaine Houle was conducted to examine the effects of wind velocity and direction as well as current velocity and direction on the number of days that it would take take to cross a water barrier during the Paleogene. Very simple summary statistics were used like in G&E Chapter 3 like mean, variance, and standard deviation. Conclusions were that around 40 mya, it would have taken about 11 days to cross the Atlantic Ocean at a most conservative measurement. The shortest measurement was 7 days. In this light, this theory does not seem all that implausible because the survival limit of monkeys has been estimated to be 11-15 days. Rafting earlier would also have decreased the amount of time. It is likely that monkeys could survive this trip and find enough food on the island to sustain them for two weeks. Now, what sort of population size would be needed, I have no idea. But imagine that Houle did this study with just summary statistics!! By the way, the link is http://www.jstor.org/view/13669516/di005208/00p0189i/0.