How does polyembryony occur in nine-banded armadillos?

In the nine-banded armadillo (Dasypus novemcinctus), polyembryony is the biological process by which a single fertilized egg develops into multiple embryos.12

Specifically, this species regularly produces litters of four identical quadruplets. These offspring develop from one fertilized egg within the uterus. While the gestation period is typically four months, it is often preceded by a variable delay period of up to several months between the fertilization of the egg and its implantation in the uterine wall.132