Impossible to verify - the problem is that we still don’t have a complete grasp of how many species there are in existence, at any given moment; to say that nature is diverse is an immense understatement. There are estimates of 5 to 100 million species of life on this planet (both plants and animals), and we have only identified 2 million of them to date. Take into account how quickly some animal species branch and you very much have a data set that is incredibly hard to quantify. Also keep in mind, of the uncounted and unstudied species, there are many that are such fast evolvers that by the time they’ve become extinct they’ve already branched into several other species, in this essence extinction is very much a natural part of evolution. That is not to say, that extinction due to destructive human activities are an entirely natural part of evolution.
So beyond a number that we can’t count, let’s look at what we are can count. The International Union for Conservation of Nature (IUCN) maintains a red list of threatened plant and animal species which evaluated 47,677 species in 2009 found 17,291 species are threatened with extinction. Even if every one of those species identified to be threatened in 2009 were to disappear in 2010 that would be a daily rate of 47.4 species per day.
There is also a metric known as the background extinction rate which is more of a measure of the lifespan of a species rather than a per-year estimate.
original claim: @OMGFacts; source: MSNBC, The Good Human, IUCN, wikipedia
