See the dinosaurs:http://www.boston.com/travel/explorene/galleries/ne_murals?pg=14
My question: did all of these dinosaur species exist at the same time?
I used to have that hanging on my wall as a kid. It’s part of a larger mural that has different sections for different periods, with older periods on the left. So all of the dinosaurs depicted on the linked portion of the mural all lived in the same epoch, at least, though I don’t know if they all necessarily overlapped exactly in time.
No, but it’s not meant to be. See Wikipedia for details.