Euarchontoglires Eulipotyphla placenta discoid placenta seen in numerous groups -- humans, mice, insectivores, rabbits, rats, and monkeys A placenta in which part of the chorion remains smooth, while the other part interacts with the endometrium to form the placenta. The maternal blood cells are in direct contact with the fetal chorion. UBERON:0036154 A single placenta is formed and is discoid in shape