Megafauna - by Nina

Introduction

This report is about megafauna, a race of giant animals that existed when earth once again became habitable after the comet struck it. Most megafauna in that age were mammals but there are a few exeptions, as in birds and reptiles. I am going to focus on South American megafauna, there are two different types of megafauna, Pleistocene megafauna and modern megafauna.

I got into megafauna when I went on a trip into the northeastern Brazilian hinterlands. We went to a hotel that owned some very impressive fossils and we also had a look at a some drawings of what a few native megafauna that lived in that area are supposed to have looked like. I decided do a project on them based on what I learnt at the hotel.

I will now tell you about the Stegomastodon, Cuvieronius, Doedicurus, Megatherium and the Toxodon and the animal that hunted all of these giant herbivors, the Smilodon.

Stegomastodon

The Stegomastodon is an ancient elephant that stood 2.8m tall  and looked like a bulkier version of a modern day elephant. It weighed about 6000kg, it had two tusks like a modern elephant but they grew about 3.5m long. The Stegomastodon ate grass and it had very specialised teeth to do so, they had a complex pattern of ridges.






A full fossil skeleton is on display at the Smithsonian Natural History Museum.

Cuvieronius

The Cuvieronius was an elephant like Stegomastodon but it was slightly smaller at 2.7m tall, it had two tusks that grow in a cork screw pattern. It evolved 4.6 million years ago in North America but moved to South America when the two continents joined, bones and bits of hide have been found south as Chile. Cuvieronius is a herbivor but it probably ate a whole range of of food such as leaves, branches and grass.

A fossil skull  is displayed in the Museum National d'Histoire Naturelle Paris.

Doedicurus

Doedicurus is an ancient, giant mammal that resemebled a reptile that has a shell like an armadilo, a head a bit like a tortise and a long tail that had a ball of spikes on the end. Doedicurus  was about 1.5m high and 4m long. It was a herbivor and lived in grasslands and woodlands. Its fossils have been found in South America and North America.

 

Megatherium 

Megatherium is a giant sloth that had huge claws and was about 8m long and was about the size of a modern day elephant and weighed 4000kg. The giant sloth usually walked on all fours but by fossilized foot prints it could have stood on two feet to reach up and get the  juicyest leaves from the top of the tree, it was thought to have a long tongue to pull leaves off a branch.

A full fossil skeleton is on display at the Natural History Museum, London.

Toxodon

The Toxodon is an animal that had a rhino like body and a head like a hippo. The Toxodon was first thought to be an amphibian but after looking at the tibia and the femur and the position of its head scientists had to conclude it had  features similar to an elephant and a rhino and could not be a water dwelling animal. Charles Darwin was the first European person to discover the Toxodon and he bought a skull off a native. The Toxodon was a herbivore, and ate mainly leaves and twigs, it had a speacilised jaw to do so. The Toxodon probably went extinct because of over hunting.

There is a full skeleton in Buenos Aires.

Smilodon

The Smilodon or sabre-toothed tiger was the top of the food chain in the Pleistocene era. It was big enough, fast enough and strong enough to kill animals as big Toxodon and juvenile Cuvieronius.



There are three diffrent types of Smilodon, Smilodon gracilis, Smilodon fatalis and Smilodon populator. Smilodon gracilis was the smallest and  weighed about 55 to 100kg, Smilodon populator was the biggest and had a shoulder height of about 120cm, it weighed about 220 to 400kg.



The Smilodon was the biggest cat to ever live, it had a short tail, powerful legs and long canine teeth. They are more robust than any cat alive. It has long front legs and short back legs giving it the look of a hyena. It's teeth were fairly fragile and could not bite through bone so it did not use them in bringing the prey down, it used them in killing the prey, it can slice through the juglar and wind pipe in one bite.

It would have had a wide range of prey including deer, tapirs and ground slothes and some of the larger species may even have preyed on juvenile mammoths and mastodons.






A full skeleton is on display at the National Museum of Nature and Science, Tokyo, Japan.

Why Megafauna Nearly Went Extinct

 The Pleistocene megafauna nearly went extinct, there are a number of theorys about the circumstances. One theory is that a comet struck earth and brought climate change and disease. Another is that an ice age occurred and lots of animals went extinct, or it could have been just climate change or disease or a combination and the most likely answer is humans hunted them. The Pleistocene megafauna NEARLY went extinct, if it had gone extinct modern megafauna would not have been abel to evolve. All the Pleistocene megafauna went extinct a while ago, exept maybe a handful of animals such as the salt water crocodile, the others are represented by their often smaller modern day relatives.

Conclusion

I have just told you about the Stegomastodon, Cuvieronius, Doedicurus, Megatherium, Toxodon and the Smilodon and about when they evolved, whether they were a herbivour or a carnivour and and there apearance.