AFTER DINOSAURS

Dinosaurs vanish from the Earth Something killed off all of the dinosaurs 65 million years ago. We don't know exactly what it was, but many scientists believe it was a large comet or asteroid that struck the coast of what it now Central America. There were also other possibilities, such as disease, climate change and the rise of mammals. Mammals had been around since the Triassic, but approximately 65 million years ago they moved into the ecosystem slot vacated by the dinosaurs when they disappeared. Imagine a little, mouse-sized fur ball that had for its entire life, and that of millions of generations before it, been eating bugs and dinosaur leftovers. Much of its time was spent dodging the giant feet of bigger and stronger dinosaurs, hiding from the sharp teeth of the smaller ones, and avoiding birds and flying reptiles. Then one morning (it probably took a few years) it woke up and there were no more dinosaurs - and as an added bonus most of the birds had vanished too. This is what would have happened after the extinction at the end of the Cretaceous Period.

Mammals become dominant land animals Following the extinction, this little mammal and others of its kind assumed the dinosaurs' spot in the ecosystem to sit atop the food chain. They evolved, overly roughly five million years, from little mouse-sized creatures to become mammals the size of a house. Eventually, just like the first amphibians left the water to have an easier life, some mammals decided to leave the land and return to the water where it wasn't as competitive, thus the first whales and dolphins were born.

Mammals became highly specialized about 35 million years ago About 35 million years ago the first cats appeared and, despite what dog lovers may say, cats ruled. The sabre-toothed cat family alone was probably the most successful hunting design ever created in nature, and as a family, they lasted longer than any dinosaur family did. In fact, they were so successful that many scientists believe that if it wasn't for man, they would still be around today. For a while, man was one of their primary food sources. When we discovered tools, however, the tables were turned and man essentially bit back - killing not only the cats, but their other major food source, the mammoth. It is therefore likely that man is responsible for the extinction of the saber-tooths and the mammoths.

The Earth has changed dramatically over the last 65 million years In addition to these well-known mammals, the last 65 million years has seen quite a few changes. First off, the environment changed drastically. The continents continued to break up and this had a dramatic effect on climates around the world. It got colder and sea levels dropped as water began to freeze at the poles. Plants changed - now there was lots of grasses and flowering plants. Birds really took off - in fact in some parts of the world where there were no big cats, some birds grew huge and became terrible predators that were over 10-feet-tall and had 3-foot beaks. These were called "Terror Birds." For a while, it almost seemed like birds could have become the big predators - ironic if in fact birds evolved from dinosaurs.

Man appeared roughly 4 million years ago Then about 4 million years ago a fairly small creature appeared in the valleys of Africa. This little guy was really a little "guy" - a recognizable human ancestor. It walked upright, had a really large brain relative to its body, and ate both meat and plants. Unfortunately, it wasn't very strong, had small teeth and no real claws. Just about anything that found one of these things could eat it if it wanted to. There was just about no way it could survive, except for one thing - it had that big brain. It was apparently smart enough to stay out of the way (most of the time) of all the things that wanted to eat it. And while it was hiding, it figured out how to fight back. This began man's ascendance to the top of the natural world. In fact, many would argue that man is the most prolific killing machine ever to inhabit this planet.