What's The Largest Vertebrate The World Has Ever Known?

Pictured: all the incorrect answers.

It's not the blue whale.  That's what we've been taught to parrot our whole lives when someone asks, "What's the largest vertebrate ever to exist on Earth?" We think we're being smart, because we're not guessing a dinosaur; apatosaurus or argentinosaurus, perhaps, which were both in fact slightly shorter -- and far lighter -- than the blue whale.

But we'd still be wrong.  Sort of.  I'll explain.

The answer could be Amphicoelias fragillimus, a sauropod dinosaur discovered in 1877 whose femur bone was estimated to have measured 13 feet long, and whose single vertebra came in at an astonishing 8.9 feet tall.

We're talking about a long-neck dinosaur that, should its proportions match the closely-related diplodocus, would've stretched as long as 196 feet from tip to tail -- twice as long as the blue whale, the length of five city buses, or two diplodoci.

Click the image and get ready to scroll to the right.

The reason you don't find this guy listed in the Guinness Book of World Records, however, is because all known fossils of amphicoelias disappeared soon after their discovery and are presumed destroyed by most interested parties.

Paleontologist Edward D. Cope had two vertebrae, a pubis (hip bone), and a femur to work with when he published his findings in August, 1878.  The specimen had been preserved in soft mudstone, which crumbles very easily, and in fact the species name fragillimus means "very fragile."  The only illustration that Cope published was a rear-view of said-vertebra, which was unusual for Cope, who usually published multiple illustrations of his specimens taken from all angles.

Furthermore, it wasn't Cope who actually discovered amphicoelias, but rather a local Colorado bone hunter named Oramel Lucas, who had the fossils shipped, still encased in strata, to Cope, on the East Coast, for study.

We know that the bones arrived there safe.  Nobody knows what has happened to them since.

Cope knew better than to speculate on the total size of amphicoelias.  A total estimated length is not included in his report.  At the time, dinosaur science was in its late infancy, and paleontologists had little data at their disposal.  Those who guesstimated were seeking headlines, not the advancement of science.

But by 1994, the body of work concerning sauropod proportions was greatly expanded, and that's the year that the 196-foot estimate was produced (actually, anywhere from 131 to 196 feet, but both measurements would beat the blue whale).

In recent years, some scientists have carefully studied Cope's monographs and concluded that amphicoelias was probably representative of a fully-grown diplodocus, and not a new species altogether.  With no actual specimens to study, the scientific community will not decide conclusively one way or the other, but, should other fossils come to light and the theory prove accurate, amphicoelias, being named first, would replace the name diplodocus in textbooks around the world.

In the meantime, let us bask in the glorious image of a dinosaur as long as fully-grown blue whale, plus two city buses.

--Serge

PS: While amphicoelias may have the blue whale beat for length, nothing will ever come close to the blue whale for weight.  Being a water-dwelling creature, the blue whale can live with a mass that would flatten any land-dwelling creature.  The most liberal mass-estimates for amphicoelias come in at about 122 tons, while the heaviest blue whale ever recorded boggled the mind at 195 tons.