Which dinosaur?

I have been happily watching 'Primeval' for the last few weeks, http://www.itvmedia.co.uk/default.asp?section=104&page=406&subpage=2043 enjoying all the mindless violence and scary monsters while I tucked into my teatime pizza, and I suddenly wondered which dinosaur was my ancestor. (Fellow addicts of 'Walking with dinosaurs' and so on will know us birds are descended from the coolest creatures who ever lived.) If my great-great-great........great -great- great- grandad was a diplodocus or T. Rex, that would explain my immense size, so I could stop worrying about going on a diet. Or maybe I was an allosaur - or a stegosaur? Who knows!

Anyway, whichever it was, I bet I looked completely brilliant. (Although I probably didn't have my trademark cool shades.)