The pliosaur Kronosaurus. Still NOT a dinosaur.

… this week New Scientist’s cover story took a closer look at the four major taxa of marine reptiles, in all their incarnations from the Permian to the Big Cretaceous Sleep. I covered two of them in my post on “Sea Monsters” — the plesiosaurs and the mosasaurs — but there are two others: the icthyosaurs and the pliosaurs. You should definitely have a look.

And scientists announced this week that they had found the skull of a giant pliosaur in the UK that could have measured 16 meters (52 feet) long – only two meters shorter than the current pliosaur record-holder, a Pliosaurus found in Oxfordshire, UK, that was so big you could fit your arm in its tooth sockets.

Able I was ere I saw Svalbard.

New pliosaur specimens have been popping up all over recently. They come from Mexico, the UK, and the island of Spitsbergen in the Hoth-like waste of the Norwegian Svalbard archipelago, which is apparently bursting with pliosaur brittle (thousands of skeletons are presently weathering out in the choice spot). Two massive pliosaur specimens (est. length 15 m.) were excavated recently there and dubbed (in King-Kong-worthy choices) “The Monster” and “Predator X”.

The icthyosaurs(fish-lizards) — which resembled dolphins even more strongly than the short-necked plesiosaurs — were dominant marine reptiles in the Triassic and early Jurassic. Some small species had freakishly large frisbee-sized eyes (for reasons revealed in the NS article). But some had bodies to match — and this is relatively recent news too. It was only in 2004 that an icthyosaur — Shonisaurus — the size of a fin whale (the second-largest living animal) was found in British Columbia.

Why were neither of these creatures in “Sea Monsters”? The icthyosaurs died out for unknown reasons by the time “Sea Monsters” was. . . er . . . “filmed”. So had the largest pliosaurs.

The New Scientist article also features a difficult to find but stunningly informative and useful family tree and size comparison chart for the four groups. Make sure to blow that puppy up so you can actually read it.

One final note . . bear in mind that the animals in the New Scientist tree (and our current maximum size estimates for particular groups) represent what we know based only on the fossils we’ve happened to find. There may have been many more varieties of huge marine reptiles in these four groups — or maybe another major group – and any of them could be larger or weirder than we’ve ever imagined. Good specimens may never have fossilized properly, purely by chance. The fossils may be buried in rock layers that aren’t currently much exposed at the surface, and are waiting miles underground to be exposed thousands or millions of years hence (or never). Or long ago they may have weathered out and eroded back into the sea whence they came or been sucked down into the mantle and obliterated.  Odds are we are seeing only a slim fraction of what once existed.

And that is true for all life, especially in the squishy-little-creature category of which I’m such a fan. Biologists, perhaps even more than historians, have reason to lament our inability to time travel. Oh, what wonders we might see if we could. The fossil record, with all its glorious variety, is the merest hint of the splendor that really was, that really happened, and that we will never, never know.

Our heroine . . . Dolichorhynchops . . . and her droogs.

Some life is weird by virtue of time delay. If the inhabitants of the Cretaceous Seaway — the long strip of semi-shallow ocean that flooded middle North America some 82 million years ago — could see the vast blubbery mammals that inhabit the seas today, they would no doubt think them odd. And tasty.

But it so happens we live now, not 82 million years ago, and it is we that them them odd. You see, in that time, the oceans were filled not with mammals who put out to sea, but with reptiles who did. Large reptiles. With nasty big pointy teeth.

The niche presently occupied by dolphins was occupied by icthyosaurs (although they had gone extinct by 90 million years ago) and small plesiosaurs like the four-finned marine reptile Dolichorhynchops (Do-li-ko-rin’-kops), the Lambda-class shuttle of the Cretaceous Seaway. That of the Loch Ness Monster was occupied by long-necked plesiosaurs. And the niche occupied by sharks was occupied by mosasaurs and . . . well. . . sharks.

Growing up, I was curious about these mysterious seas and the creatures that inhabited them. But I only had a dim idea of what they were like because the only places to find them were line drawings in books or bones in museums, where they generally took a big backseat to media-darling dinosaurs. Because, and this is a big point to remember, folks – especially if you’re talking to paleontologists – these sea creatures are not dinosaurs. Not Dinosaurs. Remember that. In my college dinosaurs textbook (“Dinosaurs: The Textbook”), one of only two places pleiosaurs show up is in the section on ancient reptiles that are not dinosaurs. Dinosaurs, according to “Dinosaurs: The Textbook”, can be most easily thought of as a group of extinct reptiles having an upright (not sprawling or swimming) posture. Paleontologists seem quite sensitive on this point.

Enter Sea Monsters: A Prehistoric Adventure — the latest (first?) offering by National Geographic in the world of gargantuan IMAX films. It seeks to fill in this Cretaceous-Seaway-sized gap in our collective imagination. To see the trailer for “Sea Monsters: A Prehistoric Adventure”, click here. I saw this at the Denver Museum of Nature and Science two weeks ago at a special screening with a lecture on the science behind the film by paleontologist Ken Carpenter. A Dolichorhynchops is the heroine of the film, but the directors couldn’t resist shortening her name to the overly-cute “Dolly”( Can’t we just say Dolichorhynchops? Please? Is it really that much harder to say than Dmitri Medvedev or Boutros Boutros-Ghali?).

The directors worked with Carpenter to develop the most scientifically accurate reconstructions of these creatures possible. And wow, what a wonderful job they did. Though the plot is a bit treacly (hence the moniker “Cretaceous Bambi” bestowed on the film by Carpenter at the end of my screening), the animations are stunning. Though assuredly, there are gratuitous eye-candy shots of the giant predatory mosasaur Tylosaurus leaping in slow-mo toward the viewer for the benefit of the 3D patrons, they also made sure to include some ostensibly less-glamorous creatures. A mating swarm of glowing red ammonites, for instance. And they used an absolutely fantastic “time lapse” device to illustrate the incomprehensibly vast sweep of geologic time.

Carpenter explained that the filmmakers took pains to vet every detail, behavior and design to make sure they were realistic as possible. He’d circle errors and write in corrections on stills. He’d endure marathon hours-long phone-call editing sessions. The directors even persuaded a husband and wife team of professional swimmers to latch on to one another and don plesiosaur flippers to test how a creature like Dolichorhynchops with four fixed fins might have used them in practice. They quickly found they must beat together to get anywhere, and the animators found while working with their computer models that the fins couldn’t flip up – a detail that paleontologists had missed until the animators pointed it out.

The human parts of the plot are, however, far less successful than the reconstructed animals. Poor acting. Poor scripting. I cringed. At one point, a fossil is being “excavated” by some paleontologists — but you can clearly see the outlines of the fake fossil cast they apparently plonked in the ground to stand in for a real fossil.

But far worse than that were the scripted “scientist” scenes, which I hated the for all the same reasons I hate Macgillivray-Freeman films: cheesy, fakey dialogue and acting and totally unrealistic depictions of scientists. The lead female scientist was particularly unbelievable, inauthentic, smug and annoying. I have worked with women scientists. I know women scientists. Women scientists are friends of mine. Madam, you’re no woman scientist.

In short, she falls victim to the Elizabeth Shue effect. Ever see “The Saint”? The last decent Val Kilmer movie in which he plays a man of many disguises who falls for the impossibly beautiful, but completely unconvincing physicist? It’s not that some female scientists aren’t beautiful — see Lisa Randall. But when directors hire gorgeous actresses to play brainy scientists, the results are usually not good (exception: Jodi Foster). I mean, come on — how many female scientists do you know that look perfectly coifed and attired with a chic haircut and perfect make-up to go digging in the dirt of backwater Kansas? Couldn’t we film some real scientists on a dig for some relevant fossils rather than relying on fake scientists with even faker dialogue? In my opinion, it isn’t fair to kids to misrepresent science this way. They’re trying to turn them on to science, and to my adult brain at least, the result is both misleading and a turn-off. For a film that took such pains with getting even the tiniest angle of a fin on a fish in the background just right, why couldn’t they take such pains with the depiction of science and scientists?

Still, the movie works more often than not and it captures a world whose story has gone untold far too long. At one point, “Dolly” barely escapes death by shark, but she doesn’t escape having a back flipper nipped and permanently tucked. And sure enough, as Carpenter showed us in his slide show, scientists have actually found a fossil Dolichorhynchops flipper with its back edge missing a shark-bite sized piece.

Just don’t forget Lesson #1. One of the very first slides in Carpenter’s presentation was a dinosaur with a big red circle with a line through it. He took questions after the film, and an audience member asked something about the dinosaurs in the movie. Carpenter looked as though he’d just been hit by a sniper. “Oooooh . . . ” he winced. “NOT dinosaurs.”

To see if the film is playing in your area, click here.