Lecture 71 – Lecture 72 – Lecture 73 Primates Ozgur Unal NIS - BIOLOGY Lecture 71 – Lecture 72 – Lecture 73 Primates Ozgur Unal

Primates List the similarities and differences you see among the primates in the pictures. All primates have a common ancestor. What is the basis for this statement?

Characteristics of Primates Humans, apes, monkeys and lemurs belong to a group of mammals called primates. Though primates are highly diverse, they share some general features: Manual dexterity Senses (eyesight) Locomotion Complex brains Reproductive rate Manual dexterity: Primates are distinguished by their flexible hands and feet  five digits on each hand and foot The first digit on most/many primates’ hand & feet are opposable. An opposable first digit is set apart from the other digits  What is the advantage?

Characteristics of Primates Senses: Primates mostly rely on vision and less on their sense of smell than other mammals do. Their eyes are protected by a bony eye socket. Eyes are at the front of their face  overlapping vision called binocular vision. What is the advantage of forward looking eyes? Most primates are diurnal  active during the day  color vision Some primates are nocturnal  active at night  black and white Flattened faces  better binocular vision Teeth reduced in size and usually unspecialized  suitable for different types of diets

Characteristics of Primates Locomotion: Primates have flexible body They rely on hind limbs for locomotion. Most primates live in trees and have developed an exrtaordinary ability to move easily from branch to branch. When on ground, all primates except humans walk on four limbs. Many primates can walk upright for short distances. They have a more upright posture compared to 4-legged animals.

Characteristics of Primates Complex brains and behavior: Primates tend to have a larger brain in relation to their body size. Their brains have fewer areas devoted to smell and more areas devoted to vision, memory and coordinating arm and leg motion. Many primates have problem solving abilities and well-developed social behaviors (grooming and communication).

Characteristics of Primates Reproductive rate: Most primates have fewer offspring than other animals. Usually, one offspring at a time Long pregnancy Newborns are dependent on their mothers for an extended period of time  this allows for the increased learning of complex social interactions Check out Figure 16.2!! What factors threaten some primate population?

Primate Groups Primates are large, diverse group of more than 200 living species. Most primates are arboreal, or tree-dwelling, living in tropical or subtropical forests. Primates that live on the ground are considered terrestrial primates. Primates are classified into two subgroups based on characteristics of their nose, eyes and teeth: Strepsirrhines  wet nosed primates Haplorhines  dry nosed primates The haplorhines include anthropoids, a group of large-brained diurnal monkeys and hominoids.

Strepsirrhines Strepsirrhines can be identified by their large eyes and ears. They predominantly rely on smell for hunting and social interaction. Mostly found in Madagascar and nearby islands. Some can be found in Asia and Africa. Check out Table 16.1!! Most small lemurs are nocturnal and solitary. Only a few larges speices (Figure 16.4) are diurnal and social.

Haplorhines The second group of primates include tarsiers, monkeys and apes. The apes in turn include gibbons, orangutans, gorillas, chimpanzees and humans. The tarsier is found only on Borneo and the Philippines. Small, nocturnal creature with large eyes. It has the ability to rotate its head 180 degrees like an owl. Lives in trees.

Haplorhines Anthropoids are generally larger than strepsirrhines and they have larger brains relative to their body size. They are more likely to be diurnal They have more complex social interactions. They tend to live longer than strepsirrhines. Anthropoids are split into two groups: New World Monkeys (Americas) Old World Monkeys (Africa, Asia and Europe)

Haplorhines New World Monkeys: 60 species of arboreal monkeys New World monkeys include tamarins and marmosets  they lack fingernails and opposable digits Most of the New World monkeys are distinguished by teir prehensile tails. A prehensile tail functions like a fifth limb. It can graps tree branches or other objects and support a monkey’s weight  Figure 16.5

Haplorhines Old World Monkeys: Old World monkeys live in a wide variety of habitats thgourhout Asia and Africa. There are about 80 species in this group including macaques and baboons. They are diurnal and live in social groups. None have prehensile tails, and some have no tails. Most Old World monkeys have opposable digits.

Haplorhines Apes: Only a handful of ape species exist today. Apes generally have large brains in proportion to their body size than monkeys Longer arms than legs, barrel-shaped chest, no tails and flexible wrists They are classified into 2 subgroups: the lesser apes and the great apes. The lesser apes are the arboreal primates of the ape family. They have the ability to walk on either 2 or 4 legs like all great apes, but they generally move from branch to branch using a hand-over-hand swinging motion called brachiation.

Haplorhines The great apes include orangutans, gorillas, chimpanzees and humans. Read the textbook as you go over each species. Orangutans are the largest arboreal primates. Gorillas are the largest of primates (predominantly terrestrial). Chimpanzees and bonobos have well developed communication systems, such as body positions and gestures. Humans are classified in a separate subcategory of hominids called hominins. Hominins are humanlike primates that appear to be more closely related to present-day humans than they are to present day chimpanzees and bonobos. Though many species of hominins existed on Earth, only one species survives today.

Primate Evolution Most primates today are arboreal with prehensile tails, long limbs, binocular vision, brachiation and opposable digits. Primates evolved from ground-dwelling animals that searched for food in the top branches of forest shrubbery. Then they evolved into additional food-gathering niches in trees. Opposable digits help them grasp tree branches and catch insects. The rise of flowering plants also provided new niche opportunities.

Primate Evolution Primate Ancestors: Genetic data suggests that the first primates probably lived 85 mya. The earliest primate fossils  Altiatlasius  60 mya Altiatlasius was a small, nocturnal animal that ate insects and fruits using its hands and feet for grasping.

Primate Evolution Diverging Primates: Lemurlike primates were widespread by about 50 mya and many species existed on all continents except Australia and Antarctica. Sometime around 50 mya, the anthropoids diverged from tarsiers. The earliest anthropoids leaped less and walked more than strepsirrhines and tarsiers. 30-35 mya, the anthropoids had diverged and spread widely.

Primate Evolution Displacement: Many strepsirrhines appeared to have become extinct by the end of Eocene  due to change in climate or the divergence of anthropoids The anthropoids of this time generally were larger and had bigger brains than strepsirrhines. Today, nocturnal strepsirrhines do not interact with the diurnal anthropoids when the habitats of these two groups overlap.

Primate Evolution Monkeys: At the end of Eocene, the monkeys appeared. Early monkeys had larger brains than their anthropoid ancestors and their eyes were more forward looking. They relied less on smell. New World Monkeys diverged from the line that gave rise to Old World Monkeys sometime between 35 and 25 mya. New World Monkeys  America Old World Monkeys  Africa How did the New World Monkeys arrive at America?

Primate Evolution Journey to South America: Many scientists hypothesize that the New World Monkeys evolved from an isolated group of ancestral anthropoids that somehow drifted to South America from Africa. By rafts of vegetation and soil.... Sea levels were lower and the continents were closer.

Primate Evolution Aegyptopithecus: In Africa and Asia, anthropoids continued to evolve. Many anthropoid fossils have been found at a site in present-day Egypt called the Fayum basin. Now a desert, the Fayum was tropical when dozens of anthropoid species lived there 36-31 mya. The largest among them was Aegyptopithecus often called the dawn ape. This arboreal animal, which was the size of a domestic cat, was ancestral to the apes. It might have been part of the anthropoid line that split from the Old World monkeys and might have given rise to orangutans, gorillas, chimps and humans.