I believe this show is from the late 80's or early 90's. It is about a father and daughter who found a "portal" to a prehistoric land. It aired on Saturday mornings. Any ideas ?

I think you might be thinking of Land of the Lost. Let me know if I am wrong though!

Marshall, Will and Holly
On a routine expedition
Met the greatest earthquake ever known
High on the rapids It struck their tiny raft (insert screams here)
And plunged them down a thousand feet below
To the Land of the Lost
To the Land of the Lost
To the Land of the Lost Lost Lost lost!
Sleestaks rocked LOL

Man, the cartoons back then were amazing, I can remember things like sharky and george, about a shark and a puffer fish I think, they were detectives, bestest thing everz.

What else, Mighty max!! Whoah, I so wanted him as my best mate. (some of those episiodes where actually scary)

And, Konan or something, some mussely guy with a big sword. (still talking about early 90's cartoons)

Biker mice from mars! Mice, who were from mars who were bikers! Ingenious.

Maybe Land of the Lost?

I think I remember that too. Land of the Lost sounds right.

I remember a cartoon that there where like a circus and they would change with the power of crystals and fight for good

From amazing adventures cartoons