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#           Cenozoic      

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Cenozoic (66 million years ago until today) means ‘recent life.’ During this era, plants and animals look most like those on Earth today. Periods of the Cenozoic Era are split into even smaller parts known as Epochs, so you will see even more signposts in this Era. Cenozoic signposts are colored yellow. 

Cenozoic signposts are colored yellow. The images show the art on the Trek Through Time signposts. The name of each epoch is a link to the entire plaque installed on the Trek Through Time.

### *Paleogene Period: 66-23 million years ago*

### **Paleocene Epoch:** 66-56 million years ago

**What did Earth look like during the Paleocene Epoch?**

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                            - Sea level fell to expose dry land on much of inland North America, Europe, Africa, and Australia.
                            - By the end of the Paleocene, North America's last large inland sea was gone.
                            - South America, Antarctica, Australia, India, and Africa were all separate continents.

**What was Earth’s climate like?**
                            - The climate during the Paleocene was much warmer and more uniform than today.

**What animals were on Earth****during the Paleocene Epoch****?**
                            - After the massive extinction at the end of the Cretaceous, evolution once again proceeded rapidly.
                            - With their dinosaur competitors gone, many new mammals evolved. 
                            - The first rodents, armadillos, primitive primates, and ancestors to modern mammalian carnivores appeared.
                            - However, none of these Paleocene forms were any bigger than a small bear.
                            - Many of these early mammals were unsuccessful competitors, and few exist today.
                            - Although the dinosaurs were gone, reptiles, such as snakes, lizards, turtles, and crocodiles persisted. 

**What plants were on Earth****during the Paleocene Epoch****?**
                            - New plants quickly evolved, and the first pines, cacti, and palm trees appeared. 
                            - Flowering plants continued to diversify rapidly.

**What was Virginia like****during the Paleocene Epoch****?**
                            - During the Paleocene, much of coastal Virginia was under water.
                            - Central and western Virginia were rolling lowlands and hills.
                            - The ancient Appalachians had eroded away, and the modern Appalachians had not yet formed.

**What else happened during the****Paleocene Epoch****?**
                            - At the end of the Paleocene there was a sudden global warming.
                            - The exact cause for this temperature increase is unknown but may be related to the release of carbon dioxide (CO 2 ) and methane (CH 4 ) into the oceans and atmosphere.
                            - Atmospheric and ocean circulation patterns changed, and there were significant extinctions in some deep-sea organisms and a major turnover in land mammal species. 

 

### **Eocene Epoch:** 56-34 million years ago

**What did Earth look like during the Eocene Epoch?**

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                            - At the beginning of the Eocene, India, which had been moving slowly northward, collided with Asia, and this force started to push up the Himalayan Mountains.
                            - Australia rifted away from Antarctica and began to move northward. By the end of the Eocene, the gap between these two continents was large enough that the Circum-Antarctic Current first started flowing.
                            - This changed ocean currents around the world and resulted in a global cooling event at the end of the Eocene.
                            - Sea level was high during much of the Eocene, which submerged large portions of most continents.

**What was Earth’s climate like****during the Eocene Epoch****?**
                            - During the Eocene, temperatures were warmer than during any other time in the Cenozoic.
                            - There was a lot of rainfall but no seasons, no glaciers, and similar temperatures throughout most of the globe.
                            - Palm trees and alligators were able to live within the Arctic Circle.
                            - By the end of the Eocene, temperatures had dropped drastically, and seasonality had returned. This had profound effects on the plants and animals. 

**What animals were on Earth****during the Eocene Epoch****?**
                            - The increase in diversity of mammals that began in the Paleocene continued in the Eocene.
                            - The first whales, bats, primitive elephants, and hoofed animals appeared. 
                            - The first giant mammals roamed the Earth.
                            - The first horse-like animals lived in the Eocene, but they were the size of dogs and had toes instead of hooves.
                            - Eocene primates more closely resembled modern forms.
                            - Birds also continued to diversify with the appearance of penguins, pelicans, ducks, and gulls.

**What plants were on Earth****during the Eocene Epoch****?**
                            - The highly successful flowering plants continued to diversify until they filled most environments on the land. 

**What was Virginia like****during the Eocene Epoch****?**
                            - The coastal plain of North America from New Jersey to Texas was under a warm shallow sea.
                            - Tropical rain forests covered the now gentle slopes of the Appalachians.
                            - There were some volcanoes in western Virginia. 

**What else happened****during the Eocene Epoch****?**
                            - Near the end of the Eocene, there is evidence of several extraterrestrial objects striking the Earth.
                            - Remnants of these craters can be found in Russia, Belarus, Canada, and the United States at the southern part of the Chesapeake Bay.
                            - It is still uncertain if they all happened simultaneously and what effect they had on the planet. 

 

### **Oligocene Epoch**: 34-23 million years ago

**What did Earth look like during the Oligocene Epoch?**

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                            - More of North America was dry land than in the preceding Eocene Epoch.
                            - The Gulf Coast remained flooded, but the Atlantic Coast north of South Carolina was dry land during most of this time.
                            - India pushed farther into Asia, South America separated from Antarctica, and Australia continued to move away from Antarctica.
                            - There was a significant increase in volcanic activity in Europe and in North America.
                            - Yellowstone National Park is a remnant of this activity.

**What was Earth’s climate like****Oligocene Epoch****?**
                            - The climate, which had been warm and moist in the Eocene, became cool, dry, and seasonal.
                            - For the first time in the Cenozoic, Antarctica was covered extensively with glaciers, which lowered sea level.
                            - Farther north, temperate forests replaced subtropical forests.
                            - Near the end of the Oligocene, savannas (grasslands with scattered trees) appeared.

 

 

**What animals were on Earth****during the Oligocene Epoch****?**
                            - As temperatures lowered, seasonality increased, grasslands appeared, and the body size of mammals increased.
                            - A huge, hornless rhinoceros from Asia was the largest land mammal ever to live.
                            - As forests diminished, some animal species adapted and became grazers.
                            - Many species could not survive the change in climate and perished. 
                            - Many other new forms evolved that could cope with the savanna's limited hiding places.
                            - Early forms of monkeys, dogs, cats, rhinoceroses, pigs, and camels were present. 
                            - Horses increased in size, with longer legs and fewer toes for faster running. 

**What plants were on Earth****during the Oligocene Epoch****?**
                            - The cooler, drier, more seasonal climate of the Oligocene was ideal for the evolution of numerous species of grasses.  

**What was Virginia like****during the Oligocene Epoch****?**
                            - Most of Virginia was above sea level and had a temperate climate. 
                            - During the early and late Oligocene, there were a few brief periods of time when parts of Virginia were under water.

###  

### *Neogene Period: 23-2.6 million years ago*

### **Miocene Epoch:** 23-5 million years ago

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**What did Earth look like during the Miocene Epoch?**
                            - Because of continental plate movement, new mountain ranges formed during the Miocene in North America, South America, Europe, and Africa.
                            - There was continued uplift of the Himalayas and renewed uplift of the Appalachians.
                            - The polar ice cap continued to exist on Antarctica.
                            - Africa and Asia were now connected by land bridges, as were North America and Siberia.

**What was Earth’s climate like****during the Miocene Epoch****?**
                            - There were warmer conditions in the first half of the Miocene.
                            - In the latter half of the Miocene, increased mountain building, combined with changing ocean currents and polar ice on Antarctica, led to decreased rainfall, increased seasonality, and cooler temperatures.
                            - As a result of this climate change, the forests continued to shrink in size and grasslands spread even more widely.
                            - The first true prairies appeared and covered much of the continents. 

**What animals were on Earth****during the Miocene Epoch****?**
                            - With increasing grasslands, hoofed mammals, with their multiple stomachs suitable for digesting the tough grasses, flourished.
                            - There were great mammal migrations from continent to continent over the land bridges.
                            - For example, elephants first migrated to North America at this time.
                            - The abundance and diversity of mammals was at its highest.
                            - The most significant event for human beings, however, was the appearance of the first anthropoid apes.

**What plants were on Earth****during the Miocene Epoch****?**
                            - The two major plant changes were the major expansion of grasslands and the appearance of kelp forests in the oceans. 

**What was Virginia like****during the Miocene Epoch****?**
                            - Although the western part of Virginia was involved in active mountain building, the coastal plain of Virginia was under water.
                            - Marls, clays, sands, and diatoms were being deposited there, forming shales, sandstones, and diatomites.

 

### **Pliocene Epoch:** 5-2.6 million years ago

**What did Earth look like during the Pliocene Epoch?**

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                            - By the beginning of the Pliocene, the continents were in very similar positions to where we find them today.
                            - The Cascade, Rocky, and Appalachian Mountains were forming, as well as the Colorado Plateau.
                            - A shift in the Caribbean Plate connected North and South America at the Isthmus of Panama, and this provided a land bridge for mammals to migrate across. 
                            - The Mediterranean Sea dried out and was a grassland for several million years. 
                            - The Himalayan Mountains continued to rise.

**What was Earth’s climate like****during the Pliocene Epoch****?**
                            - The first half of the Pliocene was warmer than the world is today, and sea levels were higher.
                            - During the last half of the Pliocene, temperatures dropped, and there was less rainfall.
                            - Not only did the ice cap on Antarctica grow larger, there also was an ice cap at the North Pole.
                            - Scientists still aren't sure what caused these climatic changes that eventually led to the ice ages of the Pleistocene epoch.

 

**What animals were on Earth****during the Pliocene Epoch****?**
                            - Most of the plant and animal groups would be recognizable to us today, although the individual species were different.
                            - The emergence of the land bridge between North and South America in the late Pliocene made it possible for many animals to migrate into new regions.
                            - Armadillos, ground sloths, opossums, and porcupines moved into North America, and dogs, cats, bears, and horses moved into South America.
                            - Many animals became extinct because of the new competition.
                            - The modern horse evolved, and hoofed animals reached their peak on the grasslands.
                            - Early hominids in Africa evolved into several distinctly different species with only one of them surviving to the present day as modern human.

**What plants were on Earth****during the Pliocene Epoch****?**
                            - Grasslands and savannas expanded significantly due to the cooler, drier climate.
                            - The vegetation species were very similar to those of today.

**What was Virginia like****during the Pliocene Epoch****?**
                            - The shape of North America was similar to the present, except for a wide strip along the Gulf and Atlantic coasts, which was under water.
                            - In Virginia, marls and clays were being deposited in a shallow sea that extended as far west as Petersburg.  

 

### *Quaternary Period: 2.6 million years ago to the present*

### **Pleistocene Epoch:** 2.6 million to 10,000 years ago

**What****did Earth look like during the****Pleistocene Epoch?**

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                            - The position of the continents was essentially the same as it is today. 
                            - However, the outline of the continents changed as a result of the ice ages. 
                            - During a glacial period, sea level fell because water was trapped in the ice.
                            - During an interglacial period, sea level rose as the ice melted and the water flowed into the oceans.

**What was Earth’s climate like during the****Pleistocene****?**
                            - This was a time of global cooling and warming with ice ages and interglacial periods occurring about every 100,000 years.
                            - We are in the beginning of an interglacial period right now (as of 2020).
                            - During the glacial periods, the northern quarter of the globe was covered with ice. 
                            - At its maximum, the ice was 13,000 feet thick, and sea level dropped about 430 feet.
                            - During the interglacial periods, much of the northern ice melted, and the glaciers retreated northward.
                            - The ice on Antarctica, however, which melted much less during interglacial periods, gradually increased in size. 

**What animals were on Earth****during the Pleistocene****?**
                            - Many plants and animals survived to live on the planet today, but many others did not.
                            - There was a significant number of large animals (i.e., mammoths, mastodons, saber-toothed cats, and giant ground sloths), but few of them survived.
                            - Their extinction was probably due to stresses from the fluctuating climate and being hunted by humans.
                            - By the end of the Pleistocene, modern humans had spread throughout most of the world except Antarctica.

**What plants were on Earth****during the Pleistocene****?**
                            - During interglacial periods, forests were dominant.
                            - When the climate cooled, grasslands expanded, and tundra dominated.

**What was Virginia like****during the Pleistocene****?**
                            - In Virginia, there were no glaciers because they didn't extend farther south than New York City.
                            - As sea level rose and fell, the coastal plain of Virginia was either under water or dry land.
                            - The climate extremes ranged from tundra in the western mountains during glacial periods to warm temperate conditions near the coast during interglacial periods.
                            - The spruce and hemlock forests found today on north-facing slopes and higher mountains are remnants of broad forests that once covered the state during glacial periods. 

Back to the Mesozoic

Back to the Paleozoic

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