EXTINCT | Species that Have Vanished | Anton Gill

This book is absolutely excellent - a really absorbing history of six very different lost species. It starts with three ice age creatures: the mammoth, sabre-tooth tiger and Irish elk (a giant deer type thing). Interestingly, we don't really know why they died out, and various theories - climate change, disease - are put forward and explained by the author and the various experts interviewed.

The second half of the book covers three species much closer to our era: the dodo, great auk  and the extremely odd Tasmanian tiger. The most interesting is the Tas tiger - one of those strange Australian marsupials that seemed to be its own evolutionary dead-end. Considered a pest and hunted to extinction in the 20th century, it truly is a cautionary tale.
The book is well illustrated with lots of diagrams and photographs (harrowing b/w shots of pathetic Tasmanian tigers in the zoo particularly effective).

If you're interested in natural history and ecology, I'd thoroughly recommend this book. It's also full of accounts of human endeavour and exploration, like 'Longitude' or 'Cod' - well worth a read!