her love's a pony, my love's subliminal

Here's an easy way to get freaked out and depressed at the same time: most animals that ever lived on Earth are now extinct.  Thank God this also counts "natural" extinctions, "prehistoric" ones, the ones we're not responsible for.  When the aliens examine us millions of years in the future, as the sun is dying, our rule will be called the dark ages: the most repressive and the bloodiest, but thankfully, the briefest.  I project that in the future Earth will be ruled by a race of terrible mice that may or may not have the power of flight, like the ones in Stephen King's "Night Shift". 

This is quite sad, really: "In the 1920s two German zookeepers, the brothers Heinz and Lutz Heck, attempted to breed the aurochs back into existence (see breeding back) from the domestic cattle that were their descendants. Their plan was based on the conception that a species is not extinct as long as all its genes are still present in a living population. The result is the breed called Heck Cattle, 'Recreated Aurochs', or 'Heck Aurochs', which bears an incomplete resemblance to what is known about the physiology of the wild aurochs."