29.7 The Evolution of Primates

More than 1/3 of the 330 living species of marsupials are found in Australia, with the rest found in the Americas and South America.

The koala, bandicoot, and several other Australian animals are called koalas.
Unlike monotremes, the embryos of marsupials are nourished by a yolk-sac, but without an egg shell.
The embryo can enter an embryopause and delay development until it is implanted.

Fetal young are also Marsupial.

The very premature young reside in a pouch in which they receive milk and continue their development.
The young joeys nurse for about a year and a half.

The devil is native to Australia.

There are about 4,000 species of mammals in 18 to 20 orders with many different ways to live.
They have been successful in form, diversity, and abundance.
There are two major clades of the eutherian mammals.
The Atlantogeneta include the Afrotheria and the Xenarthra.
The Euarchontoglires have many familiar orders, including Scandentia, Rodentia, Lagomorpha, and the Primates.
The major Laurasiatherian orders include horses and rhinos.
The two largest orders are the rodents and bats, which make up about 60 percent of all eutherian species.

By the end of this section, you will be able to describe the derived features that distinguish primate from other animals, as well as describe the defining features of the major groups of primate.

The mouse lemur is 30 grams (1 ounce) larger than the mountain gorilla.

The evolution of primate characteristics allow us to understand the evolution of our own species.

All primate species are descended from tree-dwellers.

The hands and feet are adapted for climbing because of the arboreal heritage of primate.

The brains of primate are larger than those of most other mammals, they have claws that have been modified into flattened nails, and they have a tendency to hold the body upright.

Haplorhini and Strepsirrhini are two groups of primate.

The bush babies and pottos of Africa, and the lorises of Southeast Asia are examples of prosimians.

tarsiers and simians are included in the Haplorhines, which include humans, apes, and monkeys.
strepsirrhines tend to be nocturnal, have larger olfactory centers in the brain, and have a smaller size and brain than anid.
Haplorhines are diurnal and depend more on their vision.
The difference between the strepsirrhines and haplorhines is that the haplorhines have to get their vitamins from their food.

The smallest primate is Carlito syrichta, which is about 5 inches long from nose to tail.

The tail is twice the length of the body.
The large eyes and long hind legs are the same size as the animal's brain.
Proto-primates are the first primate-like mammals.
They were similar to tree shrews in size and appearance.
Most of the fossil evidence is from North Africa.
Until more fossil evidence is available, these creatures are largely unknown.
The oldest primate-like mammals with a relatively robust fossil record date to about 65 million years old.
The teeth and skeleton of the Proto-primate Plesiadapis were similar to those of true primates.
They were found in North America and Europe in the Cenozoic.

In North America, Europe, Asia, and Africa they were found.

The early primate were similar to present-day prosimians.

The early prosimian species went extinct due to cooler temperatures or competition from the first monkeys.

Anthropoid monkeys evolved from prosimians.

Evidence shows that monkeys were present in the New World and the Old World by 40 million years ago.
New World monkeys are referred to as Platyrrhini because of their broad noses.
Old World monkeys are referred to as Catarrhini because of their narrow noses.
There is still uncertainty about the origin of the New World monkeys.
The continents of South American and Africa were separated at the time of the platyrrhines.
It is thought that monkeys came to the New World either by drifting on log rafts or crossing land bridges.
Old World monkeys include both arboreal and ground-dwelling species, whereas the New World monkeys are all arboreal.
The arboreal habits of the New World monkeys are reflected in the possession of prehensile or grasping tails by most species.
Some Old World monkeys have thick patches of skin on their seats, and the tails are never prehensile.

The howler monkey is native to Central and South America.

It makes a call that sounds like it's made by a lion.
A shrew is larger than a monkey and does not have a tail.
Many apes spend most of their time on the ground, but they are capable of moving through trees.
When walking quadrupedally, monkeys walk on their palms, while apes support the upper body.
The apes have larger brains than monkeys.
There are two groups of apes.
All great apes have the same skeleton.

The gibbons are smaller than the great apes, they have low sexual dimorphism, the sexes are not markedly different in size, and they have relatively longer arms for swinging through trees.

There are two orangutan species in Indonesia, Borneo and Sumatra.
The Batang Toru forest in Sumatra has a third orangutan species.
Orangutans are solitary and arboreal.
The cheek and throat pouches of males are larger than that of females.
There are animals in Central Africa.
The eastern and western populations of the gorilla are separate from one another.
The males are twice the size of the females.
The hair on the back of older males is gray or white.
Chimpanzees are considered to be the most closely related to humans.
The bonobo is closely related to the Chimpanzees.
Chimpanzees and bonobo separated about 2 MYA, according to genetic evidence.
Chimpanzees and bonobos live in Central Africa, but they are separated by a river.
Chimpanzees have shorter legs but have more hair on their heads.
Chimpanzees keep their white tail tufts for the rest of their lives.
Chimpanzees have lower-pitched voices than Bonobos.
Chimpanzees are more aggressive and sometimes kill animals from other groups.
Chimpanzees and bonobos are very affectionate.
Fruits for orangutans and foliage for gorillas are the main food items in the Orangutan and gorilla diet.

A gibbon is a lesser ape.

In gibbons, females and infants are buff and males are black.
One of the great apes is a young chimp.
It has a large brain and no tail.

The great apes and humans are included in the Hominidae of order Primates.

Evidence from the fossil record and a comparison of human and Chimpanzees' genes suggest that humans and Chimpanzees are different from each other.
Our species is the only surviving member of the evolutionary branch that includes humans.
The term hominin is used to refer to the species that evolved after the split of the primate line.
A number of marker features differentiate humans from the other hominoids, including upright posture, a fully opposable thumb, and an increase in the size of the brain.
Bipedal hominins include several groups that were probably part of the modern human lineage--Australopithecus, Homo habilis, and Homo erectus--and several non-ancestral groups that can be considered "cousins" of modern humans.

It is difficult to determine the true lines of descent.

The course of evolution from early hominins to modern humans was thought to be shown from oldest to youngest when relatively few hominin fossils had been recovered.
In the past several years, many new fossils have been found, and it is clear that there was more than one species alive at any one time, and that many of the fossils found are hominin species that died out and are not ancestral to modern humans.

The chart shows the relationship between humans and hinnins.

There are three species of very early hominids that made news in the late 20th and early 21st centuries.

Ardipithecus, the youngest of the three species, was discovered in the 1990s.
Several more specimen of Ardipithecus were discovered in the intervening years and it was shown that the organisms was bipedal.
Two species of Ardipithecus have been identified, A. ramidus and A. kadabba.
The status of this group as a human Ancestor is uncertain.

The oldest of the three was discovered in 2001 and has been dated to seven million years ago.

There is a skull that was found in Chad.
The mosaic of primitive and evolved characteristics of the fossil, informally called "Toumai," is not clear as to how it fits with the picture given by the data.
It is not thought that this species was an early descendant of modern humans.

In 2000 there was a new species found, called Orrorin tugenensis.

There are several different types of Orrorin.
The features of Orrorin are similar to those of modern humans.
If Orrorin is a human descendant, the Australopithicenes may not be in the direct human line.
They may help to clarify their role.

The southern ape went extinct about two million years ago.

The great apes have many of the same characteristics as modern humans.

Sexual dimorphism was more exaggerated in modern humans.
The ratio of males to females was similar to that seen in modern gorillas and orangutans.
Modern human males are larger than females.
The brain size of the great apes is similar to that of the humans, but it is smaller.
Bipedalism is one of the key features of modern humans that is similar to that of Australopithecus.
The footprints were 3.6 million years old and were similar to those of modern humans.
The hominins were upright at the time.

Many of the australopiths are referred to as australopiths.

About 4.2 million years ago, a person named Australopithecus anamensis lived.
More is known about the early species, which lived between 3.8 and 2 million years ago.
The reduction of the dentition and jaw in size is a trend in human evolution.

The brain size was close to that of a modern Chimpanzee.

The prognathic jaws are a bit longer than those of modern humans.

It was the most complete australopith fossil found, with 40 percent of the skeleton recovered.

The skull of an early hominid that lived between two and three million years ago resembled that of modern humans but was smaller with a sloped forehead, larger teeth and a prominent jaw.

Lucy was discovered in the mid-1970s.

Like other early hominids, it had robust arm bones and may have spent time in trees.
The brain size of A. afarensis was 500 square centimeters, which is less than one-third the size of modern human brains.
Two new australopiths have been added in the last few years.

The australopiths had teeth that were good for soft food.

Over the past several years, fossils of different body types have been found and dated to 2.5 million years ago.
The hominids of the Paranthropus were muscular and had large grinding teeth.
The heavy wear on their teeth suggested that they had a vegetarian diet as opposed to the australopiths.

Paranthropus robustus of South Africa and Paranthropus aethiopicus and Paranthropus boisei of East Africa are included.

The hominids in this group went extinct more than one million years ago and are not thought to be related to modern humans.

Between 2.5 and three million years ago, the human genus, Homo, appeared.

For a long time, fossils of a species called H.

H. habilis had many of the same features as modern humans.

The australopiths and a larger brain had a jaw that was less prognathic than that of H. habilis.
Some features of older hominin species were retained by H. habilis.
The stone tools that have been found with the remains of H. habilis are referred to as "handy man."

The link between hominin eating of meat and evolutionary trends is explained in this video.

About 1.8 million years ago, H. erectus appeared.

It is believed that it was the first hominin species to leave Africa.
The features of H. erectus were more similar to modern humans than to H. habilis.
H. erectus was larger than earlier hominins, reaching heights up to 1.85 meters and weighing up to 65 kilograms, which are similar to modern humans.
The degree of sexual dimorphism was less than in earlier species, with males being 20 to 30 percent larger than females, which is close to the size difference seen in our own species.
The earlier species of H. erectus had a larger brain than today's humans, with an average of 1,130 to 1,260 square centimeters.
The nose of H. erectus was similar to that of modern humans and it had a forward-facing nose.
Longer, downward-facing nostrils allow for the warming of cold air before it enters the lungs and may have been an adaptation to colder climates.
The first hominin to use fire, hunt, and have a home base is thought to be H. erectus.
It is thought that H. erectus lived until about 50,000 years ago.

Homo erectus had a nose that pointed downward.

A number of species are thought to have evolved from H. erectus about 500,000 years ago.

There are three species of Homo heidelbergensis.
The brain size of modern humans is between 1,200 and 1,400 square centimeters.
They had a thick skull, a prominent brow ridge, and a receding chin.
Some of the species were overlap with modern humans until 30,000 to 10,000 years ago.

The Homo neanderthalensis may have worn clothing.

About 1.5 million years ago, H. erectus migrated out of Africa and into Asia and Europe.

Modern humans migrated out of Africa about 100,000 years ago in a second major migration wave.
Modern humans replaced H. erectus species that had migrated into Asia and Europe.

The evolutionary timeline is supported by evidence.

One way to study the origins of modern humans is to look at the mtDNA from populations around the world.
The maternal line is the only one where a fetus develops from an egg containing its mother's mitochondria.

The timelines of genetic divergence can now be estimated with the help of the mtDNA.

Evidence shows that all modern humans are descended from a common ancestor that lived in Africa about 160,000 years ago.
One way to understand human evolution is to look at the Y chromosomes, which are passed from father to son.
Evidence shows that all men are descended from a man who lived in Africa about 140,000 years ago.

The Denisovans were identified through the study of mitochondrial DNA.

There were two things that were suggested by the DNA from teeth and finger bones.
The genetic makeup of modern humans and Neanderthals was different.
The Denisovans had a common ancestor with the Neanderthals.

Neanderthal and Denisovan genes have been found in modern human populations, indicating that interbreeding occurred over part of their range.

A notochord is a hollow later in a fish's life cycle.

Early gnathostomes were able to exploit new food tubular nerve cord.

The cartilaginous fishes and thelancelets are included in the two clades of invertebrates in Chordata.

Lancelets feed on mammals.
A cartilaginous fish include sharks, rays, skates, and other organisms.
Cartilaginous fishes live on the ocean floor and are suspension feeders.
All of their lives, the habitats with a few species living in fresh water for part or the two invertebrate clades is more closely related.
The majority of present-day fishes to the vertebrates are being debated.
Almost 30,000 species are part of the clade Osteichthyes, which consists of named for the vertebral column.
Actinopterygii (ray-finned fishes with a cranium) and sarcopterygii (lobe-finned vertebrata) are the two clades of the name Craniata.

The hagfishes and lampreys are among the four members of the tetrapods.

Some salamanders that feed on dead animals are limbless, but Hagfishes are well-developed limbs.

The lungs of birds have air spaces in them that are found in the adults of many species.

All animals have small teeth.

Birds are modified and belong to a group.

The archosaurs are three classes of living Amphibia.
Birds, salamanders, and caecilians likely evolved from theropod dinosaurs within the archosaurs.
The oldest known fossils of adinosaur in two distinct stages are that of Archaeopteryx, which is dated from the metamorphoses into an adult stage, acquiring lungs.
The tail of modern birds is lost in Anurans.

There are different levels of parental care in the salamander.

The mammals have hair and mammary glands.

The amniotes are similar to the salamanders in that they have the secretory glands, eccrine presence, and apocrine glands.

The amniotes have a single bird and mammal.

The early amniotes had two openings in the skull behind the eye.
The first amniotes probably created main lines for mammals.
The initial evolved from synapsids and sauropsids in the late Triassic period.

Endothermy is a key characteristic of synapsids.

There are three groups of mammals, but a number of them have been lost.

Over evolutionary time, monotremes are reduced.
For unique among mammals as they lay eggs, limbless reptiles are classified as birth to young.
Because they descended from ancestors with four young, Marsupials give birth to very immature tetrapods.
It was one of the key adaptations that allowed reptiles to pouch.
Eutherian mammals are called placental live on land due to the fact that all species of mammals have a complex placenta which prevents water loss from the skin.

Milk is derived from modified sweat and is used to nourish young Crocodilia and Sphenodontia.

The classification is paraphyletic and leaves out the birds, which are now classified as avian reptiles.

Birds and not all living species are arboreal.

Birds are the most speciose group of land vertebrates, with brains that are larger, relative to body size, than display a number of adaptations related to their ability to fly, those of other mammals, claws that have been modified into which were first present in their theropod.

Birds have a high metabolism that makes them upright, they are endothermic, and they have a tendency to hold the body.
Most prosimians have feathers that allow them to retain their own body heat, as well as a considerable amount of heat, which is divided into two groups.
simians are included in these haplorhines.
Prosimians were used to regulate the internal temperature of monkeys.
The simian line is largely independent of ambient thermal.

The lesser apes and the greater are divided into two groups.

There are apes with flight feathers.
There is a lot of debate about the origins of Neanderthals and Denisovans, which can be considered "cousins" of humans.
New evidence from fossil finds and genetic uprightness, the first evidence of bipedal hominins, will continue the discussion about whether modern humans were walking or not.

There is a hollow nerve cord.

The pharyngeal slit becomes the b in fishes.

The chorion is used for gas exchange.

She found that the a. cephalochordates species has a mostly cartilaginous skeleton and b. echinoderms swim bladder.

There was a person with gills.

The members of Chondrichthyes had four limbs.

By having (a) _____.

Monotremes include:

A bird is a dinosaur.

The hip structure supports bipedalism.

Primary feathers a.

The eccrine glands produce something.

The notochord and the clade Anura are the same structure in adults.

The evolution of jaw musculature allowed birds.

It's hard to determine the sequence of the skeleton.