Mammal Body Size Distribution

This is a follow up to Mammal Body Size by Continent.

We have previously compared the average masses of extant and extinct species on different continents to try to understand whether size has an influence on extinction in mammals. Looking at the averages was a good start, but we really need to look at the full distributions of masses of the two groups to get the best picture of whether or not there was a major size bias in extinctions during the late Pleistocene. Make a graph for each continent that you think is worth visualizing. Each plot should facet two histograms that use the same bins to display the number of extinct and extant species. Use the log(mass) rather than the mass itself so that you can see the form of the distributions more clearly. Label the axes appropriately.

There is a lot of work to do in this problem so make sure to break it down in to manageable pieces. Some logical chunks include:

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