I read a book back in the late 70's and here's what I remember:
There were a group of people who 'bought a tour' to time travel back to the dinosaur era.
They travel on a disc shaped platform.
There is some trouble and some die.
The main hunter/protagonist goes off and hunts down the T-Rex that is causing the problems.
In the end, the T-Rex almost destroys the platform, but at the end of the hunt/fight, the protagonist kills the T-Rex and only the head remains, on the saucer, so that the remainder of the party now has a trophy.
I remember that the weapons were discussed quite a bit, and were not 'big game/big bore rifles' like we have today. They were 'Sci-Fi', not laser, but maybe particle weapons, or mass weapons of some kind.
I do know it is not Turok nor “A Sound of Thunder”.