The Quaternary Period: Animals, When It Happened, and Major Events

A trio of woolly mammoths trudges over snow covered hills.
© Daniel Eskridge/

Written by Krishna Maxwell

Updated: October 6, 2022

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This is the period most of us think about when think about the rise of early humas or we hear the term ice-age. This was a period of many extreme changes brough about by shifting continents, massive volcanoes that affected the world’s climate, and huge extinction events. The quaternary period was marked by the rise and fall of giant animals and the emergence of humans.

The Quaternary period is the last period of the Cenozoic Era. It is a period known for the many glaciations and glacial retreats. The extinction of huge birds and mammals happened during this period, which left room for the appearance of the human species. The Quaternary period is divided into the Holocene and Pleistocene epochs.

What are the vital events that took place during this time? Let us study the following information and understand the animals, chronology, and major events of this period.

The Animals of the Quaternary Period

This period was marked by many temperature changes. Glaciations and warming happened abruptly. This imposed change on many of the animals that thrived during this period. Below are the two epochs of this period and the known animals in them:

Pleistocene Epoch

Giant animals or megafauna ruled this epoch. Giant mammals dominated the land. Among them were the cave bears, mammoths, giant deer, mastodons, giant sloths, and saber-tooth tigers. Wooly mammoths and camels populated North America. They were hunted down as prey by packs of giant lions and saber-toothed tigers. The North American plains were occupied by teratorn birds and giant beavers.

The oceans were ruled by giant marine animals like megalodon and hunting whales. When the Earth’s climate stabilized to its modern state, all the giant animals died off except for the whales and horses. North America’s horses became extinct as well but survived in other parts of the world. The Europeans then re-introduced them.

Scientists believe that it was either too much hunting or too much cold that led to the extinction of these majestic animals. Some experts support the theory of too much hunting. They believe that the ancient hominoids hunted large animals to extinction. Evidence shows broken tips of weapons stuck in large piles of bones. Other researchers believe that large animals died off because they could not adapt fast enough to the climate changes. They believe that the megalodon was one of the giant animals affected by this fatal consequence. Below are a few known giants that lived during the Pleistocene epoch:

Megalodon (Carcharocles megalodon)
Megalodons are an extinct species of sharks that grew to more than 50 feet in length.



This enormous shark dominated the oceans during the Pleistocene epoch. It was the largest fish to have ever existed. Its reign lasted for 13 million years. Scientists suggest that it grew to about three times the length of the largest great white shark ever recorded and 15-18 meters high.

The extremely large teeth of these sharks may give you an idea of what they ate. The serrations implied that they would have consumed meat. Large fish, other sharks, and whales were the possible food sources for this giant shark.

Giant Sloth

The last of their kind disappeared only about 4,200 years ago. The giant sloth is one of the successful species of the Ice Age. It had 19 genera from North, South, and Central America. The species also reached the Caribbean by the end of this epoch. The largest of the giant sloths was the Megalocnus. This giant sloth weighed 200 pounds. It was as heavy as a full-grown man.

Giant Cave Bear

Europe hosted these enormous cave bears. Their large sinuses made it difficult for them to change their diet right away during severely cold weather. A giant cave bear weighed about 2,205 pounds. Plants were its main source of food. Scientists suggest that it became extinct because of the cold snap 24,000 years ago.

Other researchers say that cave bears died off because of prehistoric humans. Until now, experts still wonder how the brown bear survived the same situation. They say that the cave bears had large sinuses that prevented them from using their front teeth. These bears could only eat plants with their back teeth. During the cold snap, plants dwindle. Brown bears had smaller sinuses. This allowed them to eat meat as well. These bears survived because they were able to fatten up before hibernation.

Holocene Epoch

This is the current epoch. The modern animals you see today are related to the present air, land, and marine animals. They may be smaller than their giant counterparts in the Pleistocene, but they share genetic information. The Holocene period is a stable time. Temperate and tropical forests exist because of this consistency. Many ecosystems developed. This brought forth the different specialized animals you know. Here are two of the common animals that you may recognize from the Pleistocene:

Great White Shark

This large top ocean predator roams the coastal waters of the world. Great White sharks can weigh up to 5,000 pounds. They can grow a length of 15-20 feet. This shark’s gray upper body can blend with the seafloor if you view them from above. The white underbelly gives the shark its name. They can swim up to 15 miles per hour and breach prey like whales from underneath.

These sharks have 300 serrated teeth. These animals can detect prey easily because of their unbelievable sense of smell. They can even sense the electromagnetic fields of other animals. They feed on sea birds, other sharks, crustaceans, and even dead whales.

Brown Bear

These bears have a well-built hump on their shoulders. This large muscle allows them to dig up rocky ground and roots to find food. Sub-species of the brown bear are the grizzly bear, Kodiak bear, and Eurasian brown bear.

When Everything Happened

The Quaternary period was the time when the continents stabilized into their modern positions. The climate changed significantly during this time as well. It began with huge polar ice sheets. There were times when the glacial ice covered Asia, North America, and Europe.

Constant changes in climate continued throughout the Pleistocene. The planet cooled and warmed. Scientists noted at least 60 cycles of glacial contraction and expansion during this time. The variations in climate are caused by the planet’s orbit. These are called the Milankovitch cycles. Some scientists say that we are still in the Ice Age and that the warming is part of the temporary recession of the polar ice. Huge amounts of water were locked up in the polar sheets. This caused the sea levels to lower. The event revealed a land bridge between Siberia and Alaska.

During the early Pleistocene epoch of the Quaternary periodd, the animals were well-adapted to cold. They developed very thick fur to help them go through the frigid temperatures. The climate warmed up during the Holocene. This was when these animals were thought to have died off. Some scientists say that these animals became extinct because the early human hunted them down.

Reconstruction of Neanderthal man’s face. Neanderthals were one of the first humans to eat cooked meat.

©Hermann Schaaffhausen – Public Domain

The Major Events

Animals during this time became massive. This was brought about by the disappearance of the dinosaurs. The animals had free reign over the Earth’s environments and food sources. The advancement and retreat of the glaciers carved and molded the land. Sea levels rose and fell. This brought on the land bridges that gave the animals freedom to travel to different ice-covered lands. The last ice age finished about 10,000 years ago. Then, the sea levels rose and the land bridges disappeared. The continents then reached their current locations.

  • The Thaw – The warming resulted in the retreat of the ice sheets. It exposed the reshaped mountains. New rivers drained into huge basins. The Equator became the warm refuge of many animals and plants. This is because the carbon dioxide in the glaciers was released into the atmosphere. Aridity and precipitation were affected. Sharks and whales ruled the oceans. They existed with microscopic plankton, otters, seals, crustaceans, fish, urchins, seals, and dugongs. On land, the gigantic animals with thick fur died off.
  • The Age of Humans – The disappearance of the land giants happened almost at the same time as the appearance of hunting humans. Homo erectus appeared in Africa during the start of the Quaternary period. Eventually, hominids developed bigger brains. This resulted in higher intelligence. Homo erectus started to use fire. Some scientists say that these first humans came from Eurasia and then migrated to Africa. Then, they spread out to Eurasia to hunt and live in the colder regions. Here, they used tools and fire. Other experts say that the Homo erectus came from Africa and then migrated to Eurasia.

The Neanderthals came next. These early humans were stockier and shorter than modern humans. They also had stronger and longer arms and hands. Neanderthals used tools from bone and stone. They also wore the clothes that they made. These early humans lived in the shelters they made. Neanderthals ate animal protein because of the cold weather. Recent studies show that they ate cooked plants.

Homo sapiens were also found in Africa. They matured at a later age than Neanderthals. The long childhood gave them more time to learn from their parents and from their environment. There was a division of labor and diversification in food intake. This allowed the Homo sapiens to survive. Different food sources allowed these modern humans to take advantage of their environment, whether the climate was warm or cold.


The Quaternary period was full of dramatic changes in weather and the environment. The animals adapted as much as they could, but the drastic changes became too much for them. The weather became too unfavorable for them, but adaptive smaller animals pressed on. With them, humans rose and became the dominant species on Earth.

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About the Author

Krishna is a lifelong animal owner and advocate. She owns and operates a small farm in upstate New York which she shares with three dogs, four donkeys, one mule, and a cat. She holds a Bachelors in Agricultural Technology and has extensive experience in animal health and welfare. When not working with her own animals and tending her farm, Krishna is helping other animal owners with behavior or management issues and teaching neighboring farmers about Regenerative Agriculture practices.

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