Missouri's Massive Mammals

by Margot McMillen
Illustrated by Mark Raithel

These ancient ancestors wandered the land long before the name "Missouri" was even a dream.

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Even a great state like Missouri can get a little boring sometimes.

You walk outside, and you know what you're going to see. Trees, grass, some streets and buildings. If you wait a while, maybe you'll spot a squirrel or a neighbor's cat. No surprises.

It's hard to imagine, but your neighborhood was once a habitat for giant Ice-Age mammals, which are not at all boring. Today our state is important to scientists who study these ancient animals.

People who lived in the Ice Ages did not write. They didn't have the Internet, tape recorders, cameras or videocams. They lived in the times before written stories, so we call those early times pre (meaning "before") historic (meaning "stories"). We learn about prehistoric times from bones, teeth and footprints-the fossils-buried in the ground.

Paleontologists are scientists who study ancient life. They call the end of the last Ice Age the Pleistocene period. In the Pleistocene, animals such as the camel, musk oxen, tapirs, peccaries and mastodons lived here. Next time you're bored, think about one of those coming around the street corner!

Now imagine you're one of the first people here. It's the end of the last Ice Age-about 11,000 or 12,000 years ago. You've come with your family, a tribe of hunters who hunt with spears. Your family has found a dry cave, chased out the prehistoric wolves and bears and hopes to stop traveling for a while.

Compared to the 1990s, everything's different.

It's a bit colder, winter is longer and summer is cooler. There are swamps, shallow lakes and ponds everywhere. The land is wet from melting glaciers. Because it is wet and cool, there's a different mix of plants. For example, there are evergreen forests instead of hickory and oak. And it's not so grassy.

But most interesting to you and your people are the animals. You depend on the herds of giant mammals for your survival.

Try to imagine your people traveling to North America, following the herds. When the herds moved on, so did your family. Following the herds is your way of life and, like everyone else, you expect to grow up to make flint rock into spear points and hunt the mastodons and giant sloths.

These mastodons and giant sloths were well-suited to the cool climate of the Ice Age. They were mammals, which means that they had fur to help them regulate body temperature so they could be active in both cold and hot weather. This is a big difference compared to a cold-blooded animal, such as a reptile or insect, that depends on the sun to stay warm.

At one time, only cold-blooded animals lived on earth. No one knows why the big ones-the dinosaurs-died out. But eventually, only the smaller cold-blooded animals, such as turtles, insects and crocodiles survived.

Mammals with their insulating fur began to adapt to the new environment. They grew taller and bigger. They were mostly herbivores, or plant-eaters, and they had few predators.

In the United States, there were two types of mammal of the order Proboscidea, named for its long, probing trunk or proboscis. They are also commonly called elephant types. One of these types is the mastodon. Mastodons were adapted to living in the forests of what is now Missouri. They ate leaves, evergreen needles and bark. At 10 feet tall, the mastodon could reach food in high places and even pull trees out of the ground.

The other North American elephant type, the mammoth, lived farther north and west and was woolly. Mammoths had thick, fine hair for warm insulation and long, shaggy outer hair to protect from wind and rain.

Another big mammal was the giant sloth. Today, only two types of sloth remain, and they live in South America. They are about the size of cats. At the end of the Ice Ages, there were three types of giant sloths in North America. The Shasta ground sloth, found in the Southwest, was the smallest at 6 feet tall.

In our region, the giant sloth reached 20 feet. If it was hungry, it could push down a tree. Paleontologists believe that the sloth was extremely strong, but slow-moving. It could have been easy for a predator to kill but, like the mastodon, it had few predators.

Other giant mammals, such as the giant beaver and the doedicurus, also thrived in the late Ice Ages. Imagine jogging past a doedicurus-an armadillo the size of a pickup truck-on your way to school.

Why did these giant animals become extinct?

No one knows for sure. It was probably a combination of things, such as changing climate and plant life and a growing number of humans. From the small tribes that some scientists believe may have followed herds from Siberia to North America, there were soon many new human mouths to feed.

A group of predators can wipe out a healthy population if the prey cannot raise their young as quickly as the predators kill them. In the case of the Ice Age mammals, scientists think that man was the predator. The giant mammals couldn't reproduce fast enough.

If you were in the tribe that followed the giant mammals to our region, you would have expected your way of life to go on forever. You would grow up learning to make spears, hunt and live off the rich resources of the land. But things changed. The giant mammals became harder to find. When the giant mammals died off, the early people had to adapt and change, too.

Paleontologists always have more questions than answers about Missouri's prehistoric mammals and the people who hunted them. Research, careful observation and plain old curiosity can lead to fascinating discoveries about prehistoric life in our region. Such exploration can be fun, and you never know where it might take you.

Margot McMillen of Columbia is a frequent contributor to the Conservationist.

Where to go to learn more about fossils and early people in Missouri

Our state fossil

Way before the Ice Ages, the area we now call Missouri was under the ocean. You can find the leftover fossils of the sea critters in your county!

The crinoid is Missouri's official state fossil. It is part of the family of starfish and sea urchins. They have hard plates that cover their soft bodies.

The crinoid stem is a series of hard disks that look sort of like a spinal column or a plant stalk anchored on the ocean floor. At the top of the stem is the animal's body with a tiny mouth that catches bits of other animal and plant life as it streams by on the current.

Crinoids live in dense colonies, and their flowerlike forms moving with the current make them look like a field of flowers. They have been nicknamed "sea lily," but they are not plants. They are animals feeding on tiny pieces of food that drift by.

When crinoids die, their hard plates fall to the ocean floor. Over the years, layers of stem disks and body plates become compressed and mix with mud. They become stone. Most limestone in Missouri has crinoid fossils in it.

The best places to collect fossils are on private land where you have the owner's permission. If you want to hunt fossils, but no one wants to take you, you might look closely at old buildings that you visit. Limestone is used on the outside of buildings, and is sometimes found inside. Courthouses, banks, schools and post offices often are made of limestone. Limestone slabs also are used for table tops, fancy desk tops and even walls.

Collecting rocks or fossils on Conservation Department land or from state parks is not permitted. However, recreational gathering of rocks and fossils is permitted on Mark Twain National Forest lands. Collecting samples from caves on any public land is not allowed.

Sometimes you'll have the most fun looking for fossils in ordinary places. Try a gravel driveway or your own back yard.