The excavated bone of a mammoth.
The quaternary is the modern geological period that stretches back to the last 2.6 million years in which humans have existed. Before humans first formed civilizations, the quaternary was mostly known for the long period of glacial events and the quaternary extinction that lasted around 10,000 to 50,000 years ago for which some mixture of hunting and climate change was most likely to blame. Now fossils are all we have to remember most of the large fauna from this era.
The woolly mammoth (Mammuthus primigenius) lived on the tundra of North America and northern Eurasia from about 150,000 to 10,000 years ago, although a race of smaller mammoths lived on Wrangel Island until about 1,700 B.C. The species is in the same family as all modern elephants and is about the same size. Because of the cold climates and recent extinction, woolly mammoth remains can be found exceptionally well preserved. Remains are found most often in Siberia, where people used to unearth the ivory for trade. One stuffed mammoth was put on display at The Museum of Zoology in St. Petersburg.
The saber-toothed cat or tiger, known as a Smilodon, lived in North and South America from about 1.8 million years ago to 10,000 years ago. A smaller precursor species called Smilodon gracilis lived as long ago as 2.5 million years. It was about the size of a lion and at its heaviest could weigh over 800 lbs., so it specialized in short, powerful strikes. Its most known attribute, the long teeth, could grow up to 7 inches, about the same in both males and females, and it had a jaw that could open up 120 degrees. You can see a Smilodon fossil at the National Museum of Natural History in Washington, D.C.
Giant Short-Faced Bear
Arctodus simus was a giant short-faced bear that lived in North America between 800,000 and 12,500 years ago. The bear was one of the largest land mammals that ever existed, standing 5.3 feet at its shoulders and weighing 2,500 lbs. Because it was so big, it had to eat about 35 lbs. of meat per day. One fossil remains at the Royal Ontario Museum in Canada.
There are many extinct species of ground sloth, including Paramylodon harlani. This particular species lived between 5 million to 11,000 years ago. It was much bigger than modern sloths at around 6 feet tall while standing and had small bones beneath the skin that would have afforded it some protection. Many of its fossils have been found at the La Brea Tar Pits in Los Angeles. One of them was brought to the Texas Memorial Museum at the University of Texas.
Canis dirus, known as the dire wolf, lived in North and South America from 1.8 million to 10,000 years ago. It was around 5 feet long and weighed about 130 lbs. Although it is closely related to the gray wolf, it nevertheless is much older and does not share a direct ancestry with any currently living species. About 3,600 fossils have been recovered from the La Brea Tar Pits alone. The nearby George C. Page Museum in Los Angeles has a collection of dire wolf fossils.
The American lion (Panthera leo atrox) lived in North America from about 1.8 million to 11,000 years ago. It is closely related to the African lion and exists within the same species, but unlike the common perception of lions, this kind adapted to the cold. Since it was 10 to 12 feet long, it was the longest cat that has ever been found, but its weight of 1,100 lbs. still falls short of the saber-toothed tiger. Many fossils have been found at the La Brea Tar Pitts, so you can also see the American lion display at the George C. Page Museum.