In the taxonomic classification of the animal world, the class mammalian of the phylum vertebrate contains animals that have evolved features that are more sophisticated than those of their ancestors. The class Mammalia has been subdivided into 19 subtaxa, which are together referred to as orders. Primates are an order of mammals that comprises eutherian mammals such as monkeys and apes, among other things.

The Evolution of the Primata Class

According to the paleontological evidence discovered in North America and Europe, primates may have originated on these continents 55–60 million years ago.

1. Plesiadapis is thought to be the world’s oldest primate-like mammal, or proto primate, ever discovered. They were discovered in Europe and North America during the Cenozoic epoch, and it is assumed that they were extinct at the end of the Eocene epoch, when the dinosaurs went extinct.
2. The fossilised remains of primates have been discovered in North America, Asia, and Africa, and they date back to the Eocene epoch. They looked a lot like modern-day lemurs. Some believe that monkeys originated in the old world (Europe, Asia, and Africa), travelled over the ocean to the New World (America), and settled there by drifting on logs or on floating islands.
3. As a result, new world monkeys and old world monkeys were isolated from one another and followed different adaptive radiations throughout the course of 30 million years of evolution.
4. Prosimians first appeared during the Oligocene epoch, when they began to evolve. All existing species of modern-day monkeys have evolved over a period of around 30 million years.
5. According to recent estimates, there are between 230 and 270 primate species in existence today.

Primates have a variety of characteristics in general

1. Given that all primates are descended from tree-dwellers, they have evolved with adaptations that allow them to climb trees in order to survive. As a result of their stable ball joints and robust clavicles or collarbones, they have been able to use their arms quite successfully in tree climbing.
2. Because all primates, with the exception of spider monkeys, have pentadactylism, their big toes and thumbs are separated for grabbing (having five fingers and toes on hands and feet respectively). Gripping is made easier by the mobility of the fingers and toes, as well as the opposability of the thumb. 
3. All primates, with the exception of humans, have prehensile feet as well. Power grip is provided by partially turning the thumb and pressing it aggressively towards the fingers in the case of small world monkeys. The monkey and ape have greater dexterity and are better at gripping with accuracy. They are able to control little items more effectively as a result.
4. Primates have superior visual ability compared to other mammals since they have stereoscopic vision. When it comes to primates, visual processing is responsible for 50% of their cerebral cortex activity. The combination of colour vision and binocular vision results in stereoscopic vision.

Primates also have other traits

1. The majority of primates are arboreal, which means they live in trees (Notable exceptions are humans and gorillas).
2. The majority of primates have an upright posture in the upper body and occasionally walk on two feet (Humans are erect and always exhibit bipedalism).
3. All primates have a smaller nose, and the olfactory parts of their brains are smaller as a result (except Lemurs).
4. When compared to other mammals, primate brains are disproportionately huge in relation to their body size. The increased parts of the brain are in charge of coordinating manual dexterity, hand-eye coordination, and stereoscopic vision, among other functions.
5. When compared to the size of the animal, long gestational durations are observed.
6. The primates are, on the whole, extremely social animals.
7. Almost all primates are active during the day.
8. Grooming is an extremely gratifying behaviour that advanced primates, including humans, engage in on a regular basis.

Primates are classified according to their size and shape

Phylogenetic classifications of primates have been done, although the majority of classifications are based on similarities and differences in external morphology. Primates are divided into two suborders: the Strepsirrhini and the Haplorrhini (humans).

Conclusion

A short muzzle, a poor sense of smell, prehensile five-digit hands and feet with flat nails instead of claws, acute vision with depth perception due to the presence of forward-facing eyes, a large brain, and prolonged pre- and postnatal development are some of the characteristics that distinguish primates from other mammals. The majority of animals have a single young and live in groups led by a dominant male.