Thunder of Time — James F. David

Ten years ago, the prehistoric past collided with the present as time itself underwent a tremendous disruption, transporting huge swaths of the Cretaceous Period into the world of the twentieth century. Entire neighborhoods and cities were replaced by dense primeval jungles and modern humanity suddenly found itself sharing the earth with fierce dinosaurs. In the end, desperate measures were taken to halt the disruptions and the crisis appeared to be over.

Until now.

Slowly at first, but with increasing frequency, time begins to unravel once more. What's worse, Nick Paulson, Director of the newly-formed Office of Security Science, discovers that the time displacements are being manipulated by unknown parties, utilizing a mysterious new technology. Indeed, the very integrity of the space-time continuum appears to be at risk.

To preserve both the future and the past, Nick and his allies must uncover the secrets hidden within in a lost temple at the center of a dino-infested jungle -- and in an enigmatic structure on the surface of the moon. But they are not alone in their quest. A cult of ruthless fanatics is also intent on controlling the time waves, and they will stop at nothing to reshape history to their own design . . . .