I'm looking for a book I've read couple years ago. The plot was similar to "A Sound of Thunder" and Time Safari.
In rough sketches the plot is as follows:
A group of rich people embark on safari trip via time machine. Among them there is one hunter guy and a certain woman. Can't remember the details about her, only that at first they don't like each other and it's them at the end in that restaurant on a date.
They do safari stuff, which is starting to getting out of hand. Maybe in the middle of the story author somehow hints that dinosaurs may be invisible. In the climax there is a large fight between the humans and dinosaurs. Probably lesser creatures are influenced by those invisible ones. Humans somehow win, though one might be dead, and return to their times.
Sometime later, said hunter guy meets that woman in the restaurant. They're having a date. I think it was she, who gave him a gun. It might have been a revolver, maybe with special bullets. Then more than one dinosaur, I think, makes itself visible and attacks the couple. They fight back. I don't remember what was next.
Those dinosaurs were sentient enough to be looking for members of the original group and to have some sort of control over lesser dinosaurs.