I don't understand why scientists don't ask for a little time to make sure their findings are accurate (Brontosaurus and Apatosaurus, Ultrasaurus and Brachiosaurus, etc. I rest my case) because, as you said, too many vertebrae could be added, or in the famous case in a documentary I saw on Flyers - erp, I mean Pterosaurs (watchin' too much LBT) - called Sky Monsters; in it, an Israeli paleontologist, I believe he was Israeli, had discovered fossilized remains of what was believed to be the wing finger of a massive pterosaur - with a wingspan of forty feet. he had also found some pretty convicing tracks as well where the creature could have touched down in some area of the desert.
It would have been so much cooler had not he realized about a third of the wing bone was actually a petrified log 
WHAT?! Honestly!!
Well, in the case of WWD and other such dinosaur shows, inaccuracies are usually the fault of the filmmakers either failing to do adequate research on the creatures they're portraying, or taking scientific speculation and rough estimates and presenting them as fact because it makes for good TV. For example, if a paleontologist tells them that the fossil remains they're studying could have come from a creature that was probably between 30 and 50 feet long, but
might have been as long as 70 feet, which size do you think the filmmakers are going to run with?
I saw the show about the petrified wood being mistaken for a pterosaur wing bone, too (As if that’s not enough, the tracks later turned out to be geologically disfigured theropod footprints.
). Frankly, even I have to say that was a pretty pathetic mistake (According to other pterosaur researchers, the guy responsible is still hugely embarrassed about it). Still not nearly as bad the story of
Aachenosaurus multidens, a name given in 1888 to a fossil of petrified wood by a scientist who thought he’d discovered a new species of hadrosaur (Due to the rules of scientific nomenclature, that plant will forever be known as “many-toothed reptile from Aachen”). Apparently that poor guy was so embarrassed he resigned from science altogether.
I think most cases of paleontologists getting things wrong, however, are more a case of science marching on. For example, contrary to popular belief,
Brontosaurus wasn't synonymized with
Apatosaurus because it was a chimera (a fossil that turns out to have been reconstructed from remains of two different species, in this case
Apatosaurus and
Camarasaurus), but because sometime after that mistake had been fixed, someone decided that it was similar enough to
Apatosaurus to warrant including it in the same genus. There are still scientists out there who argue that
Brontosaurus excelsus is its own genus and species.
Ultrasauros (originally spelled
Ultrasaurus but changed because someone elsewhere had already used that name), however,
did turn out to be a chimera, part
Brachiosaurus and part
Supersaurus. Like many chimeras, it's a matter of not being easy to tell that the bones you've found belong to different species, especially when the creatures are similar, have died close together, and the bones have been scattered by water, scavengers, geological activity, or what have you.
Oh, by the way, sorry: I forgot to address your earlier question on whether
Liopleurodon was still the biggest Jurassic predator. (Wait, whose question thread is this again?
) I would assume that it or some other giant pliosaur like
Pliosaurus funkei is still at least the heaviest, though there are a few large theropods such as
Torvosaurus and
Saurophaganax (and others known from only fragmentary remains) that may have been slightly longer; in the 36–43-foot range. However, there was also an early Jurassic ichthyosaur,
Temnodontosaurus (
this page has a picture of its skull), that apparently reached 40 feet long, so it may have beaten out both the pliosaurs and the theropods for the title.
The largest predator of the entire Mesozoic that I am aware of, however, was a much older Triassic ichthyosaur,
Shastasaurus sikanniensis, which is estimated to have been at least 60–70 feet long, almost as large as the WWD
Liopleurodon. It was toothless, however, and probably fed on fish and soft-bodied cephalopods like squid, which it caught by rapidly opening its mouth to create a vacuum that sucked them down its gullet. Still a creature I’d be pretty hesitant to go swimming with. As far as toothy,
Liopleurodon-like predators go, the biggest I know of is
Mosasaurus hoffmanni, a colossal marine lizard from the late Cretaceous that reached lengths of at least 50 (possibly up to 60) feet long. In any case,
Walking With Dinosaurs sure as heck didn’t need to make up or exaggerate anything about the scariness of prehistoric sea monsters. :blink:
