That is a lot lower than I would have guessed (only 300,000 plant species on the entire planet?). I think the number of known species, 2.16 million, is the bett

That is a lot lower than I would have guessed (only 300,000 plant species on the entire planet?). I think the number of known species, 2.16 million, is the better comparison here, because we're talking about known extinctions. Also, this is just extinctions in the US, but I can't find a good number of known species that exist in the US. For one example, 10 of the 21 species labeled as extinct here are birds, and there seem to be roughly 900 species of birds in the United States. So 10 seems like a lot. There are also 8 extinct mussel species out of 297 known in North America.