“A Gift of Time,” by Jerry Merritt
I usually love time travel books, but this one didn't click for me…. I liked the bits in the past — they felt softer — but the hard-sci-fi engineer-hero-type protagonist was harder for me to connect with.
(I feel the impulse to defend my position by saying — yes, I did get this book's references to “Think Like a Dinosaur.” Still wasn't my favorite. But clever.)