Parthogenesis is essentially virgin birth. As far as I know it has never been documented in mammals, though it has been artificially induced. Theoretically, I tend to think anything is possible, however, the problem with mammals reproducing in such a way is that mammalian genetics is subject to genomic imprinting. Genomic imprinting is a bit over my head, but essentially means that certain genes in an egg or sperm are turned off and a working copy only comes from the other parent. A mammal with one parent can lack working copies of genes which leads to pretty serious developmental defects. Parthogenetic experiments on mice have shown viable offspring to be rare.