I don't hold Walking With Dinosaurs as a sacred piece of mesozoica. I enjoy it, and I do occasionally turn to it on a sleepless night as I wait for the stubborn sandman. But if I did hold it in such a regard, that faith would have take a serious hit this morning.
I'll refer you to a post at the Pterosaur Database on the ornithocheirids: a family of pterosaurs which Paul Pursglove describes as a taxonomic lost and found, of sorts. Most of what we know of this group is fragmentary, and Pursglove describes an additional source of confusion:
This problem arose from specimens collected from the Cambridge Greensand. The specimens were deposited within the Greensand from elsewhere, perhaps from moving sediments or as fossils eroded from other rocks and re-deposited. In many cases, the age and location of the original deposition is unknown.So, we've got a group of pterosaurs which are known from bits and pieces, a number of which were redeposited from their original resting places.
So why the heck did the WWD team decide to cast an ornithocheirid as the noble hero of their "Giants of the Skies" episode? Why not a better known pterosaur, one that is established as being a true species? If a giant was what they wanted, why not Quetzalcoatlus? If a visually arresting pterosaur is what you're looking for in a lead actor, there are plenty of fine candidates.
Though I'm no pterosaur expert, I've not found anything online that disputes Pursglove's post. Seems like the WWD gang drank some silly juice when they were writing that episode.