Watch the short video book trailer, then read the book:

https://www.youtube.com/watch?v=XO1PwyFffBk

Marooned in the present, their only hope for the future lay in the past. But first there was still the small matter of staying alive. The planet they were marooned on was crawling with bird-beasts, immense parrotlike carnivores that stood two meters tall, weighed upwards of fifty klogs, and had a giant scooped beak like a pelican. They normally swallowed their prey whole, though not before crushing them to death in their vise-like jaws. Then there were the vipers — writhing snake-like creatures armed with dozens of sucker-bearing tentacles. They sprayed their victims with acid, then ate them while they were still alive. But it got worse. Much worse . . . Now, join Andu Nehrengel and his three female clone companions on an intense voyage through time. First stop: the Civil War and the Battle of Shiloh, April 1862, one of the most horrendous land battles of all time. Meet Mark Twain when he is still a riverboat pilot. Journey with him north to Missouri when he joins the Confederacy. Then it’s back to the future and on to Mars!