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.