I did learn something from the questioner, though. I've never heard of a Machrauchenia before. So I guess we're all "ignorant fucks" about something. 😄
Also, the questioner implies that everyone who accepts evolution is atheist, which is not true. Only a portion of people who accept evolution today are atheist. Of the twelve largest Christian denominations in the US, about 77% belong to churches that agree with teaching evolution.
http://ncse.com/rncse/18/2/what-do-christians-really-believe-evolution
@Pat Indeed! I probably should have mentioned that, but I was going more for snark than precision.