[Ira_Louvin]

When I was a creationist, eventually I admitted that “microevolution” could happen. I figured that changes could happen within species, but it could never turn into a new species.

The problem is, as Carl Zimmer once said, “If you accept microevolution, you get macroevolution for free.” Macroevolution is just microevolution over time. Eventually, enough genetic and/or geographical drift occurs that they become new species — organisms that no longer breed with one another.

So if you believe in microevolution: Congratulations! You’re almost there!

http://unreasonablefaith.com/2008/08/12/microevolution/

[Cicero]

Well, no. Not really.

[metmom]

The problem is, as Carl Zimmer once said, “If you accept microevolution, you get macroevolution for free.” Macroevolution is just microevolution over time. Eventually, enough genetic and/or geographical drift occurs that they become new species — organisms that no longer breed with one another.

No. Macroevolution is just microevolution extrapolated and extrapolation is not science. It's a philosophical conclusion that has yet to be demonstrated in practice, and lining up a bunch of fossils is not actual observed, testable, repeatable lab work.