The end of the Cretaceous, about 65 million years ago, was marked by the mass extinction of the dinosaurs. Having served their purposes, which included: production of petroleum, formation of soil, and experimental models for mammals, and these animals were exterminated. Up to this point, mammals were limited to nocturnal, insectivorous niches. Once the dinosaurs had fulfilled their purpose and had been removed from the environment, many more mammals were developed and placed appropriately throughout the world. The first mammals were created through very extensive modifications made to a fertilized male and female therapsid reptile egg.
Modifications made to therapsid reptilian genome included:
Introduction of the 4-chambered heart.
Change arterial system to single functional aortic arch;
Make the red blood cells functional without a nucleus (enucleate erythrocytes) so they could carry more oxygen;
Add a muscular diaphragm for enhanced breathing;
Make them endothermic (maintaining a consistent body temperature);
Add hair and skin glands;
Create a complex differentiated dentition that has two generations and occludes using lateral jaw movement during mastication;
Add the Loop of Henle to kidneys:
Introduction of a larger more sophisticated brain;
Mammary glands for producing milk
Reproductive system that provided birth of live young.
Many alterations were to the skeleton.
Once a mammalian zygote was created, the real dilemma for developing the first two mammals (male and female) was finding a place for gestation of the first mammalian embryo. Since the mammalian zygote must have womb in which to develop and you cannot have a womb until you have a mammal, the first two mammals were hatched out of eggs. Then the angels had to feed the infants since there was no mothers’ milk to drink. As was the case with the development of most new species, angels built viruses to use as vectors for introduction of new genetic information. The insertion and deletion of genetic information was performed through the use of vial carried restriction enzymes. Selective breeding was another tool used by the angels.