Beyond Dinocalypse — Chuck Wendig

Thrown through time and space, Jet Black and his friends find themselves in a future that has changed everything they've ever known. Hunted, exhausted, and desperate to return home, they must stay one step ahead of the conquering psychosaurs who have taken over the world and enslaved humanity! But as the world changed, so did the people they left behind. Bitter enemies turn into vital allies and old friends sacrifice their ideals to seek victory by any means necessary in this fast-paced sequel to Dinocalypse Now!