Which evolved first, meiosis or mitosis?

While mitosis is almost always accompanied by cytokinesis, there are situations in which one of these processes may occur without the other. For example, skeletal muscle cells are very large cells with several nuclei in each cell. During the differentiation of these cells, the nucleus of a cell divides, but cytokinesis never occurs. The cell just gets bigger. Then the two nuclei divide again, and again no cytokinesis occurs. The cell just gets even bigger. So mitosis can happen without any cell division.

Meiosis clearly evolved from mitosis. The other kind of nuclear division, meiosis, accomplishes quite a different result. Unlike mitosis, which can occur in any cell which has chromosomes, meiosis can only occur in a cell with an even number of chromosome sets, usually two (diploid).

http://www.genetics.org/content/181/1/3