Are you being sarcastic? How have they determined this? You can't say definitively that an animal which lived 65 million years ago had on par intelligence with cats, but you can make an informed guess, any links? Somehow I doubt a giant reptile had on par intelligence with a predatory mammal, in this case a cat.

Edit: I just ran a google search and found this -

http://dinosaurs.about.com/od/typesofdinosaurs/tp/smartestdinos.htm

"You wouldn't think Tyrannosaurus Rex had to be particularly smart to hunt down its food--after all, this was the apex predator of its day, equipped with huge teeth, powerful legs, and a keen sense of smell. But judging by an analysis of existing skulls, T. Rex seems to have had a fairly large brain by Cretaceous standards (although today it would be outwitted by a newborn kitten)."