I suspect that you are wrong here Ed. 65 million years ago was when the (terrestrial) dinosaurs died out. The mammals evolved long before that:The earliest known mammals were the morganucodontids, tiny shrew-size creatures that lived in the shadows of the dinosaurs 210 million years ago. They were one of several different mammal lineages that emerged around that time. All living mammals today, including us, descend from the one line that survived.
Source:
The Rise of Mammals.
There is no problem with one of the larger early mammals eating one of the smaller (or very young) dinosaurs during the 145 million years that they were together.
rossum