What happens to environments when species go extinct, especially if they disappear quickly and in large numbers? How can we use what we know about extinctions of the past, and more recently to help us prevent such losses to biodiversity? Hello, I'm Anthony J Martin. I'm a professor at Emory University in Atlanta, Georgia where I teach a variety of classes in the Department of Environmental Sciences. My PhD is in geology, which means I know something about Earth processes and the 4.6 billion year history of the Earth. But I'm also a paleontologist, which means I study ancient life that's represented by fossils. At the same time, I've had to learn a lot of biology and ecology which helps me better understand how fossil plants and animals functioned and behaved in their original environments. All of this means that I wear a lot more hats than just this one, which comes in handy when learning about extinctions. Now in my experience people often confuse paleontologists with archaeologist. Well, what's the difference? For one paleontologists can study any ancient life from microbes to mammoths. On the other hand, archaeologists are mostly interested in humans and human artifacts. While most archaeologists focus on just the last 100,000 years of our species existence, paleontologists can potentially cover 4 billion years of Earth's history. Some folks might expect paleontologists to look like certain fictional archaeologist depicted in popular movies, but we can actually look like anyone. [SOUND] And yes, some paleontologists really like snakes. [SOUND] In fact this snake a western hognose otherwise known as phil serves as an example to introduce a few key concepts you'll learn in this course. One is that snakes evolve from pre-existing lizard-like species that went extinct in the geologic past. The oldest snakes known from the fossil record show up a little more than 100 million years ago, which is when dinosaurs still dominated land environments. After dinosaurs went extinct about 66 million years ago, snake somehow survived that mass extinction. And about 60 million years ago, a few got enormous and were top predators in their environments. Today snakes are extremely diverse, ranging from tiny worm snakes about the length of a pencil to giant anacondas, which can be longer than a pickup truck. But about 100 species today are also endangered. Which happened either by people killing them directly, but mostly because we've changed their native habitats so rapidly that we've lowered their chances of surviving. What will happen to these snakes and millions of other species in the near future? In this course we'll try to answer these questions and more. I hope to give you an overview of extinctions as a topic that yes is very interesting. But also convince you that it's important to learn. Better enabling us to apply the lessons of extinctions past and present to prevent extinctions in the future. Welcome to extinctions, past, present, and future. Let's get started.
