Yes they are, but the average lifespan for those species was millions of years and that number would be higher if there were no asteroid strikes. Humans killing off species in a short amount of years is a completely different scenario.
99% of a type of shark in the Gulf of Mexico are gone because of overfishing. This has led to a massive increase in the kind of fish the sharks eat. These fish eat scallops and because of their higher populations they have now wiped out entire scallop areas. Everything is connected.
Are we seeing the last lions? - CNN.com
So who cares? Well, the first thing to appreciate is that the world's large predators, like lions, are not just a luxury for us to look at, to photograph, or to shoot. They are the most vital center point in many ecosystems. If we lose them, we can anticipate eventual collapse of whole environments, right down to the water systems, as prey shifts or migrations stop, and species overgraze and destroy the integrity of important vegetation, especially along rivers.
Erosion follows, rivers silt up, and fish die, all because we took out a few lions.
There is as great an economic need to preserve lions. In Africa an $80 billion-a-year business in ecotourism feeds parks, airlines, safari businesses, and local crafts and helps pump up economies important to the entire continent.
