Cenozoic Era. The Cenozoic Era: Age of Mammals. The Rise of The Mammals. Periods: 1. Neogene 2. Quaternary 3. Paleogene 4.

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1 Periods: 1. Neogene 2. Quaternary 3. Paleogene 4. Tertiary Cenozoic Era The Cenozoic Era: Age of Mammals The Cenozoic Era is the last and most recent of the geologic eras. Its name means new life coming from the Greek root kainos, meaning new, and zoic, life. While this new life came to refer to mammals-thus coined The Age of Mammals- this new life could have just as easily been the angiosperm or flowering plants, the insects, the newest fish (teleostei) or modern birds. All of these groups, including the mammals, continued to evolve during this present Era. The Rise of The Mammals

2 During the Cenozoic, mammals evolved from their somewhat insignificant stature during the Mesozoic to include giant species that have gone extinct in modern times. While none of the mammals ever reached the size of the dinosaurs, there were some species that dwarfed their modern-day relatives. Everyone knows about mammoths, but during the Cenozoic Era some birds stood 7-feet tall. There were beavers 7 feet long! These creatures were typical of the growth achieved by the new life in the early Cenozoic. Flowering Plants Flowering plants or angiosperms were became widespread in the Cenozoic Era. They moved into niches all over the globe. Trees, grasses, shrubs and everything in between, angiosperms came to dominate many of the earth's biomes. This was beneficial to insects, many of which evolved symbiotic relationships with flowering plants. The Quaternary and Tertiary The Cenozoic includes the period that began roughly 65 million years ago to the present. Historically, the Era has been divided into two periods: the Tertiary and the Quaternary. These terms came from the 19th century when rock formation in Europe was classified as primary (being the oldest), secondary and tertiary, with quaternary being coined slightly later. As more sophisticated geologic understanding evolved, primary and secondary were dropped from use. Only Tertiary and Quaternary remained as the divisions of the era. Changes In The Naming System But these divisions don t seem appropriate in the light of current understanding about the geologic changes that occurred during the Cenozoic. New terms are being used that relate more closely and accurately to the stratigraphy of the planet: Paleogene for the early part of the Cenozoic including the early two-thirds of the Tertiary Period, and Neogene for the last part of the Tertiary and the Quaternary. Suffice it to say, regardless of what it is called, the geology that occurred remains the same! But let us not forget that the Cenozoic Era is a geologic classification and get back to the geology that distinguishes this period. The Continents Move During this time, the continents continued the separation that had begun at the end of the Mesozoic Era during the Cretaceous Period. The Atlantic Rift was widening and forcing more continental separation, in particular Greenland from Europe. Other ocean spreading rifts caused the separation of Australia from Antarctica and Africa from India. The supercontinents of Gondwanaland and Laurasia that had been the result of tectonic movement during the Mesozoic, were now transforming into the continents of modern day.

3 Volcanic Activity Builds Mountains The rifts that occurred around the globe resulted in volcanic activity that formed mountain ranges. The Cascade Range that extends along the coast of North America from British Columbia to California is one example of this rifting/volcanic activity. Volcanic activity in Europe, Asia and Africa resulted in the formation of the Himalayan and Alpine mountain systems. The Cenozoic Era: Time Marches On And so the Cenozoic era continues. It is the era we live in, though we could hardly say this is the era of humans. We have been present as a species only about 1.5 million years of the 65 million years of the current era. That represents about 7 seconds on the clock of eras!

4 The Neogene Period Major Changes For Planet Earth The Neogene Period began about 24 million years ago and it continues up to the present time. The name Neogene is a new name for part of the old Tertiary Period and includes the old Quaternary Period. Scientists changed the names of the periods when they learned new information about the age of the earth. The names will probably change again when scientists learn even more. Maybe you will help find a new and better way to name the periods of the earth s history! The chart below shows the old names and the new ones. Era Periods Epochs Traditional periods C E N O Z O I C Neogene Period Paleogene Period Holocene Pleistocene Pliocene Miocene Oligocene Eocene Paleocene Quaternary Tertiary On this page, you will read about the Miocene and Pliocene Epochs in the Neogene period. The Pleistocene and Holocene Epochs are covered on a separate page covering the Quaternary Period. The Neogene Period was a time of big changes for the earth. The climate became cooler and drier. Grasslands replaced forests. The animals had to adapt to these changing conditions or face extinction. Era Periods Epochs Millions of Years Ago CENOZOIC Era Neogene Period Holocene Quaternary Pleistocene Pliocene 11,000 yrs ago to present 1.8 mya to 11,000 yrs ago 5 to 1.8 mya Miocene 24 to 5 mya Mountains Form when Continents Collide The Neogene Period was a time when the continents were crashing into each other. Mountains pushed up in many places. India continued its push into Asia. This created the Himalayan Mountain Range. Italy moved north into Europe raising the Alps. Spain crashed into France to form the Pyrenees. The Rocky Mountains and the Andes Mountains formed in North and South America during this time. Land Bridges Bring Animals to New Lands Sea levels were lower due to the effects of continental collision. The North and South Poles began to have ice caps. During the Neogene Period, the polar ice thickened and took up more space in the ocean. The new mountains trapped water as snow and ice. All of this ice formation caused sea levels to drop even more. The drop in sea levels opened up land bridges between continents. This allowed animals to migrate between continents.

5 South America moved to the north. By the Pliocene Epoch it merged with North America forming the Isthmus of Panama. Armadillos, porcupines, ground sloths and opossums migrated from South America to North America. Dogs, cats, bears, and horses from North America crossed into South America. Forests Become Grasslands The climate continued to cool. Many of the areas that had been covered by forests were changing to grasslands. Grasses were better suited to the cool dry weather. But grasses had less nutrition than the forest plants of the Paleogene Period. It took more effort to get the nutrients out. Grasses were made of chemicals that were hard on teeth. Chewing wore the teeth down. Animals that ate grasses needed stronger teeth. Changes in the plants meant that the animals had to adapt or die. Many of the forest dwellers became extinct and new animals developed that could live on the grasses. Horses had long, flat-topped teeth that were especially good at grinding the grasses. Their teeth grew longer and kept pushing up through their gums to keep up with the wear that came from chewing. Other animals developed new ways to digest the grasses inside their bodies. These animals had more than one stomach. They are called ruminants. They were efficient at getting nutrients from the grasses. This new type of animal, the artiodactyl, developed into many familiar species: camels, bison, sheep and giraffes, to name a few. Predators Become Faster New predators evolved for the grassland environments of the Neogene Period. The grazing animals could run fast. Predators had to adapt or go hungry. The sleek bodies of the dog and cat carnivores were able to run fast and use their powerful jaws and teeth to take down their prey. They became the dominant predators in the Miocene grasslands. Miocene Ocean Life

6 There was new plant growth in the oceans, too. Kelp is a form of large brown algae. Kelp forests grew in cool waters where the plant could attach to rocks and coral. Otters and other animals evolved to live in this unique ecosystem. The dugong, a marine mammal related to the elephant and modern manatees, lived in large numbers in the Miocene kelp forests. Modern versions of these animals still feed on the plants in the Great Barrier Reef off the Australian coast. Megalodon: The World s Biggest Shark Sharks developed new species. One of these new sharks was Charcharodon Megalodon. It appeared first in the Miocene Epoch about 16 million years ago.megalodon was the largest of all the sharks. It grew to be nearly 50 feet long! To feed its huge body Megalodon dined on whales and dugongs. Megalodon became extinct about 1.6 million years ago during the Pleistocene Epoch. The Earth Enters an Ice Age The cooling climate of the Paleogene Period continued into the Neogene Period. By the end of the Pliocene Epoch the earth was locked in an Ice Age. There were many reasons that this happened. The lower sea levels, new mountains and shifting ocean currents all contributed. Ice caps grew over the polar regions. They stretched far beyond their present locations. Glaciers, growing from the ice caps, reached down as far as Ohio in the United States. The Pleistocene Epoch was beginning.

7 The Quaternary Period: Ice, Megafauna and Hominids The Quaternary Period began with an ice age about 1.8 million years ago. It is often called the Age of Humans. It continues up to the present time and is the period that we live in. It is divided into two epochs : The Pleistocene Epoch million to 11,000 years ago The Holocene Epoch - 11,000 years ago to present Each epoch has unique characteristics for climate and geography, so the plants and animals that lived during those times are unique to each epoch, too. The Geologic Time Naming System In the early 1800 s a system for naming geologic time periods was devised using four periods of geologic time. They were named using Latin root words. In Latin, quatr means four. Early geologists chose the name Quaternary for the fourth period in this system. We no longer use this system of dividing geologic time, but the name, Quaternary, is still commonly used for the most recent period in geologic time. The system for naming the periods is constantly changing. As more information is collected, analyzed, and debated, the divisions created for looking at geologic time changes. There have been recent changes to the way scientists look at this time. There was talk of dropping the old name for a new one called the Neogene Period. The old name had many defenders and there was debate about changing the name. Eventually the matter was settled and the old name kept its place. Era Traditional Periods New Periods Epochs Quaternary Period Neogene Holocene Epoch Pleistocene Epoch

8 Pliocene Epoch Cenozoic Era Tertiary Period Paleogene Miocene Epoch Oligocene Epoch Eocene Epoch Paleocene Epoch Continents Arrive at Present PositionsDuring the quaternary period the positions of the continents were much the same as they are today. What has changed during this time is the climate. The Pleistocene Epoch began with polar ice sheets far bigger than they are now. At times, the glacial ice reached far down into parts of North America, Europe, and Asia. This is commonly referred to as an Ice Age. The Climate of The Quaternary Period Generally temperatures were cooler everywhere on earth during this time. But the climate of the Pleistocene did not stay the same throughout the entire Pleistocene. The polar ice advanced and retreated. The earth warmed and cooled. Scientists have cataloged over 60 cycles of glacial expansion and contraction during the Pleistocene. Still In The Ice Age? There is a reason the polar ice advances and retreats. It isn t random. The variations are because of changes in the Earth's orbit. These are called Milankovitch cycles. The last major glacial advance was about 18,000 years ago. Some scientists say that we are still in an ice age and the current warming trend is just an interglacial period or temporary retreat of the polar ice. Glaciers Lower Sea Levels When the polar ice advances, huge amounts of water become locked up in the ice. This causes sea levels to drop. Land once covered by water is left high and dry. During a time of advancing glaciers, the Bering land bridge revealed itself between Alaska and Siberia. This happened many times during the Quaternary Period. Animals Adapt To The Cold Even though many of the plants and animals of the Quaternary Period are virtually the same as those living today, there are some important differences. First, there were certain animals that were well-adapted to the cold climate of the early Pleistocene Epoch. The wooly mammoth, mastodon, wooly rhinoceros, reindeer, and musk ox all developed thick fur to help them survive the frigid temperatures. Most of these animals became extinct when climates warmed in the Holocene Epoch. No one knows why. But as with all mysteries lots of theories have been put forth. One popular theory says that humans

9 hunted them to extinction. Another says that these animals could not adapt to the warmer climate. The only thing that is for sure is that these huge beasts no longer walk the earth! The Quaternary Period: A Time Of Giant Mammals or Megafauna The Pleistocene is known for its megafauna or giant mammals. Along with the wooly mammoth and wooly rhinoceros there were other giants: bison, ground sloths, and deer. There were giant carnivores as well. The saber tooth tiger, cave bear, and dire wolf were bigger than their modern counterparts. The megafauna disappeared at the end of the Pleistocene. All that remains are a few species of smaller, though still good-sized, animals in Africa: the elephant, hippopotamus, and rhinoceros. The Rise of Humans For us, the most important development of the Quaternary Period is the development of the hominids: Humans. From the first primates in the Tertiary Period to modern man, the hominid species has evolved amazing abilities. The earliest hominid fossils found so far date from the late Tertiary Period. They were found in Africa. As the Pleistocene Epoch continued, hominids spread throughout the world. Their larger brains allowed a level of thought and feeling that was, and is, unique among the animals. We think and solve. We change and control. The future of our planet will be greatly affected by the Age of Humans.

10 The Paleogene Period The Beginning of The Cenozoic Era The Paleogene Period marks the beginning of the Cenozoic Era. It began 65 million years ago and lasted more than 40 million years. The Paleogene is made up of three epochs: The Paleocene Epoch The Eocene Epoch The Oligocene Epoch Each epoch has unique characteristics for climate, geography, plants and animals. Era Periods Epochs Millions of Years Ago C E N O Z O I C Neogene Paleogene Holocene Pleistocene Pliocene Miocene Oligocene Eocene Paleocene 11,000 yrs ago to present 1.8 mya to 11,000 yrs ago 5 to 1.8 mya 24 to 5 mya 38 to 24 mya 54 to 38 mya 65 to 54 mya Naming the Periods of the Cenozoic In the early 1800 s, the system for naming geologic time had only four periods. The periods were named using the Latin words for first, second, third and fourth. The word tertiary means third. It was the third period in the old naming system and the first part of the Cenozoic Era. The name Tertiary is still used for the early Cenozoic, even though we have a new naming system. Today we use Paleogene for the first part. Look at the chart below to compare the new system with the old. Era Periods Epochs Traditional periods C E N O Z O I C Neogene Paleogene Holocene Pleistocene Pliocene Miocene Oligocene Eocene Paleocene Quaternary Tertiary

11 The Climate of the Paleogene Period The beginning of the Paleogene Period was very warm and moist compared to today s climate. Much of the earth was tropical or sub-tropical. Palm trees grew as far north as Greenland! By the end of the Paleogene, during the Oligocene Epoch, the climate began to cool. The Geography of the Paleogene On the chart below are some of the major geographic events of the Paleogene. Notice that on this chart, and on most charts of geologic time, the oldest time is located at the bottom. Epoch The Oligocene Geographic event Australia separates from Antarctica India crashes into Asia creating the Himalayan Mountains Antarctica is covered by glaciers Sea levels are low The Eocene North America and Europe separate The Paleocene Europe and North America are joined together Australia is joined with Antarctica India is not yet connected with Asia The Atlantic Ocean is small because South America and Africa have just separated

12 24Save This is how the earth looked at the beginning of the Paleogene Period. Look at the bottom of the chart. See if you can find the geographic events from the Paleocene Epoch. As you read the chart from the bottom to the top, try to imagine the continents moving into their present-day locations. The Rise of The Mammals The plants of the Paleogene Period are very similar to the plants that we have on earth today. The warm climate at the beginning of the period was perfect for the dense forest plants. As the climate cooled, open woodlands and grasslands became abundant. The grasses were important because they supported huge herds of grazing animals. The extinction event at the close of the Cretaceous Period wiped out the dinosaurs, large reptiles, and many other species. This left room for new animals to develop. Mammals became the dominant animals. In fact, the Cenozic Era is often called the Age of Mammals. Most of the main groups of mammals were present by the Eocene Epoch. With the dinosaurs and other large reptiles gone, mammals grew in size, numbers, and diversity. They filled ecological niches in the sea, on land and in the air. The Appearance of Common Mammals Many of the animals that we know today evolved during the Paleogene Period. On the chart below you will see familiar animals and the epochs when they first appeared. Epoch Appearance of Mammals Oligocene Dogs cats pigs toothed whales

13 Eocene bats elephant ancestors whales eohippus-the first horse Paleocene The condylarths-ancestors of mordern hoofed herbivores rodents the first primates 24Save Birds in the Paleogene The Paleogene Period favored the birds. New species evolved. There were many large flightless birds that are now extinct. These birds did particularly well until the mammals developed so many species. Many of the birds we know today were present in the Paleogene Period. The Oceans And Lakes of the Paleogene In the oceans, fish species branched out. Sharks became more plentiful. Trout and bass evolved along with many other fresh water species of fish. Huge lakes formed in the western United States during the Eocene Epoch. The Green River Formation is a famous fossil rich area created by these lakes. Many kinds of fossil fish are found in this rock formation today. Mammals developed in the oceans, too. Primitive whales, one of the largest mammals, began to develop at this time. Insects The insect population increased in the Paleogene Period. Bees and other insects that lived on the pollen and nectar of the flowering plants increased in numbers and variety. Climate Change

14 The Paleogene Period had begun with a hot and humid climate, but the climate was becoming cooler and drier. The cooler temperatures were the signal of many changes coming to the earth. The thick tropical forests would not be able to survive the cooler, drier climate. If we could go back in time and feel the climate at the end of the Paleogene, we would say it was quite warm. Compared to our climate today, it was still pretty hot! The plants and animals could feel the changing climate and as time marched into the next period, many of them would have to adapt or die.

15 The Tertiary Period: The Age Of Mammals Begins The Tertiary Period marks the beginning of the Cenozoic Era. It began 65 million years ago and lasted more than 63 million years, until 1.8 million years ago. The Tertiary is made up of 5 epochs : The Paleocene Epoch - 65 to 54 million years ago The Eocene Epoch - 54 to 38 million years ago The Oligocene Epoch - 38 to 24 million years ago The Miocene Epoch - 24 to 5 million years ago The Pliocene Epoch- 5 to 1.8 million years ago Each epoch has unique characteristics for climate and geography. The plants and animals changed from epoch to epoch also. In the early 1800 s a system for naming geologic time labeled only four periods. They were named using the Latin forms of numbers for first, second, third and fourth. The word tertiary means third. It was the third period in this system. Today, we use a different system, but the name Tertiary is still common for the first part of the Cenozoic Era. Today s system looks like this: Era Traditional Periods New Periods Epochs C E N O Z O I C E Quaternary Period Tertiary Period Neogene Period Paleogene Period Holocene Epoch Pleistocene Epoch Pliocene Epoch Miocene Epoch Oligocene Epoch Eocene Epoch Paleocene Epoch

16 R A Tertiary Climate: A Cooling Trend From Tropics To Ice Age The beginning of this period was very warm and moist compared to today s climate. Much of the earth was tropical or subtropical. Palm trees grew as far north as Greenland! By the middle of the tertiary, during the Oligocene Epoch, the climate began to cool. This cooling trend continued and by the Pliocene Epoch an ice age had begun. Period Epoch Continental Positions New Mammals N e o g e n e Pliocene Miocene Africa closes off the Mediterranean Sea North and South America join at Panama The Geography of the earth similar to today Africa is pushing into Europe-forms the Alps Arctic becomes covered with ice First hominids-human ancesters Horses,camels,and rhinos Beaver-like animals many apes and other primates P a l e o g e n e Oligocene Eocene Paleocene Australia separates from Antarctica India crashes into Asia-forms Himalayans Antarctica is covered by glaciers Sea levels are low Europe and North America separate Europe is joined with North America Australia is joined with Antarctica India a land unto itself Atlantic Ocean is forming Dogs, cats, and pigs toothed whales Bats Elephant ancestors Whales Eohippus-the first horse The condylarths-ancestors of modern hoofed herbivores Rodents The first Primates Grasses Support Grazing Animals The plants of the Tertiary are very similar to the plants that we have today. The warm climate at the beginning of the period favored dense forests. As the climate cooled open woodlands and grasslands became abundant. The grasses were important because they supported huge herds of grazing animals.

17 The Rise of The Mammals The extinction event at the close of the Cretaceous Period wiped out the dinosaurs, large reptiles, and many other species. This left room for new animals to develop. The mammals became the dominant animals. In fact, the Cenozoic Era is often called the Age of Mammals. Most of the main groups of mammals were present by the Eocene Epoch. With the dinosaurs and other large reptiles gone mammals grew in size, numbers and diversity. They filled ecological niches in the sea on land and in the air. The table above shows what mammals came on the scene with each new epoch. Hominids: Human Ancestors During the Pliocene the first hominids appeared; these were our human ancestors!

18 The Tertiary Was For The Birds Birds did almost as well as mammals during the Tertiary Period. Many of the birds we know today were present. There were also many large flightless birds that are now extinct. These birds did particularly well before the mammals developed so many species. Boney Fish and Sharks Develop New Species Fish species branched out during the Tertiary Period. Sharks became more plentiful. Trout and bass evolved. Flowering Plants Means Nectar For Insects The insect population increased in the Tertiary Period. Bees and other insects that lived on pollen and nectar of the flowering plants prospered. The Tertiary Period Ends With An Ice Age and Land Bridges The cooling climate of the Tertiary Period led to huge glaciers at the poles. The mountains of the world were also covered by glaciers, including the newly formed Himalayas and Alps. The huge amounts of water locked up in the ice lowered the level of the sea and land bridges appeared: Between Asia and North America Great Britain and Europe South East Asia and Borneo This enabled migrations of both plants and animals across these land bridges. The Tertiary period which had begun hot and humid, ended in a cold dry ice age.