That sounds very much like John McLaughlin's Toolmaker Koan. The Solar System has been watched for a hundred million years by Charon, an ancient supercomputer which is searching for an intelligent race which does not self-destruct by creating tools and weapons and...using them.
It had hopes for T-Rex (which were feathered) which developed a technological civilization about 67 million years ago, but things went very badly and Charon is forced to destroy them -- Chicxulub, anyone? Now Humans are into space and Charon wants to see how they deal with a preserved T-Rex and his spacecraft.
The human's reaction leads Charon to destroy the preserved T-Rex and place its bets on humanity.
The one hole in this match is that it was published in 1987.