Me and a friend were discussing the innacuracy of the creatures and Primeval, it has come to my attention that seemingly no one except me realizes that the Albertosaurus in New World has three fingers, something the real one doesn't have.
My friend immediately came to the conclusion that the Albertosaurus has three fingers due to genetic mutation, I agreed and concluded our conversation by theorizing that the Albertosaurus may have been the product of inbreeding.
Now to theory number 2: WHY ALL THE CREATURES LOOK SO INNACURATE
We continued our conversation and thought to ourselves that maybe there is a reason why the creatures look nothing like the real ones, maybe some sort of toxin had begun to mutate all of the creatures and ended up giving them a more cartoonish, oversized appearance that also defies the laws of physics. The Giganotosaurus is the one who I think may be the greatest subject of all this, just look at it's head, it looks more like a T. rex and it's body is too skinny and small yet somehow it doesn't trip so easily.
Don't take my word as if it were Tim Haines' or any of the writers, I'm just stating a theory that could add a certain effect to how you guys view the series.
I guess that the difference of appearances in the creatures compared to the real world creatures is that the Primeverse is different to the real world or perhaps the real world creatures could be inaccurate (considering that only bone fragment are used to reconstruct a whole skeleton).