Are Some Dinosaurs The Same As Others?

Maybe Nanotyrano whas a smaller rex

Maybe Dracorex was a juvenile Stigymolich? (I for one don't believe the Dracorex-Stigymolich-Pachycephalosaurus, but it's still a cool theory.)

I doubt it ZC. Nannotyrannus has sevral different features from tyrannosaurus. First of all its teeth. 

NannoT teeth

T.rex teeth

Now let's look at their brains..

The Nannotyrannus brain is positioned in completely different part skull then the Tyrannosaurus rexs.

Damn it HHP, i was gonna bring up the brain positioning -_- haha oh well, but yeah. That alone is a stand alone fact NannoT was a different species. No vertebrate to ever exist has ever had it's brain transition to a different posiition in the skull, why would a rex?

Also for the Pachycephalosaurus. Why would their skulls completly morph? Why would an animal grow a skull but, then completely change it. And not just once twice...

why would it start like this..

Then go to this..

Then to this...

Seriously what's the point??

Well it's a possibility I would say.

Bone doesn't drastically morph as animals age. Rhino horns, for example only grow sharper and longer as the animal matures. They do become dull as the animal gets towards the end of its life, but that isn't a feature that goes through when it hits maturity. I wouldn't say it's entirely impossible, just unlikely.

It's a cool documentary but i doubt most of it I don't think Bone morphs that much in Pachycephalosaurus and Nanotyrannus and Tyrannosaurus are definiatly different species

It's entirely possible, but I doubt it. 

This is going for species that included in dinosaurs decoded only?

my opinion:

T.rex=Nanotyrannus:Nope

Pachycephalosaurus=Stygimoloch=Dracorex:possible,50/50%

Triceratops=Torosaurus:No way!

Carnosaur - Rhino horn is not technically bone, it is keratin.

Also bone is remodeling every second  in every creature with bones, it just happens on a much smaller scale then what is being suggested here. After watching the first part of this discovery channel series episode it makes sence how bones can reshape: http://www.youtube.com/watch?v=65U3NSDn2dg&index=2&list=PL2D816042F5B7DA99 and since the bones were not directly exposed to the air, being overlayed with Keratin and with many blood vessles to feed them it is very possible for the remodeling prosses in these animls to occur. In the documentary they even gi a modern example of the horn bill.

I doubt this would have occured in many dinosaurs, but I don't see why this isn't possible.

Well now that I have read all the other comments I guess it was or is most likely that the dinosaurs were different species. Then again, we will never know.