Oops, brain freeze.

Plankton and other tiny animals and stuff in the oceans made oil, but not dino's...

I guess we call it dinosaur juice since it was made in the age of the dinosaurs.

http://www.schoolscience.co.uk/content/4/chemistry/petroleum/knowl/4/2index.htm?origin.html

The process may be continuing today, but I don't want to wait around...