The absence of feathers would eliminate the idea of including man with the other members of the class of Bird. The Reptiles are cold blooded animals and that is sufficient to exclude warm-blooded man from the class of Reptiles. Therefore, naturally, man must belong to the class of Mammals.
1. Ashley Montagu’s Classification:
He has recognised two suborders of the primates, viz., the Presidia, which includes the three infrareds Lemuriformes (Madagascar Lemurs), Lorisiformes (African and Asiatic lemurs), and the Tarsiiformes (Malayan and Philippine tarsiers) and the Anthropoidea, which is divisible into two main series, and three superfamilies.
The series are the New World Monkeys (Platyrrhini) and. the Old World Monkeys (Catarrhini). The first series comprises the super family Ceboidea, while the second series includes two superfamilies, the Cercopithecoieda and the Hominoidea comprising: the apes and man.
2. Simpson’s Classification:
Characteristics of Primates
1. The Primates bear flat nails upon their digits. This makes the grasping function of the hands and feet easier.
2. The presence of well developed clavicle is a characteristic feature of the Primates.
3. The orbits are completely surrounded by bony rims.
4. The limbs are prehensile and adapted for arboreal life. This was probably an earliest mammalian characteristic.
5. Either the thumb or the great toe or both are opposable. This possibility, which is an ancient mammalian feature, has been retained by the Primates during their long arboreal life.
6. The teeth are adapted for mixed food-vegetarian and animal. Three kinds of teeth are present in the Primate, at least at one time of its life. The teeth are differentiated into incisors, canines and molars to serve different functions of cutting, holding and grinding, etc.
7. In the Primates the mamma are two in number and they are pectoral in position, $1 nursing habits of the mother determine the position of the mammary glands.
8. The development of the brains of the Primates shows wide variation. But a calcarinefa and a posterior lobe is always present in the primate brain.
9. The primates possess pendulous penis. The character is shown by some other mammals also.
10. They have a well developed caucus (a sac connected with the intestine of an animal).
11. The stomach is simple.
12. The femur has never third trochanter.
13. The testes are descended into the scrotum. Of course, it is present in many other agile and active mammals also.