Aquatic Dinosaurs? Not So Fast!

In 1941, Czech paleo-artist Zdeněk Burian created one of the most iconic dinosaur images ever. I saw it four decades later, in one of my childhood science books, and the illustration amazed me as soon as I saw it. I still love it. Not because it’s correct, but because the painting so beautifully captures an obviously incorrect idea.

The painting, in careful detail, shows a trio of Brachiosaurus neck-deep in a prehistoric lake. Two poke their grinning heads above the surface, while a third plucks a gob of soft aquatic plants from the silty lake bottom. It was reproduced in a TIME/LIFE young readers nature library book on evolution, and I fondly remember opening the book to that page and taking in the Jurassic scene.

I am surprised this strange sauropod imagery was cherished by so many for so long. Brachiosaurus was a little more streamlined than an office building, and if the dinosaur led a watery life, it looked capable only of sticking its pylon-like legs into the muck and waving its head around to strain algae. And then there was the Goldilocks problem—an aquatic Brachiosaurus would require rivers and lakes of just the right size and depth to survive. To make matters worse, Brachiosaurus would have needed to haul themselves out and go looking for mates in other hot tubs if the species was to continue. Despite recent suggestions that these huge dinosaurs were capable of amorous aqua-acrobatics, I’m not convinced the exceptionally air-filled, buoyant sauropods could have pulled off the required underwater maneuvers. Brachiosaurus, and its counterpart Giraffatitan from the Jurassic of Tanzania, were creatures of the terrestrial realm, just like all other sauropods.

In fact, with the exception of feathery dinosaurs that took to the air, all dinosaurs were land-dwellers. This fact has been amply documented by studies of dinosaur anatomy and trackways and by attempts to reconstruct the habitats where dinosaurs actually lived. After all, paleontology relies on a combination of anatomy and geology, and by pulling at those two threads paleontologists have been able to investigate how dinosaurs interacted with the various habitats they called home—be they fern-covered floodplains, dense forests, or sandy deserts. To pick just one example, paleontologists Chris Noto and Ari Grossman recently reviewed the pattern of global ecology during the Jurassic dinosaur heyday and found that aridity—which affected vegetation in prehistoric forests—influenced the abundance and variety of herbivorous dinosaurs present in different parts of the world. As paleontologists keep digging and poring over what has already been found, the ecology of the dinosaurs is coming into clearer and clearer focus.

All of which is to say that I was dumbfounded when the BBC’s Today program ran a sensationalist story about a so-called dinosaur debate that isn’t really a debate at all. You can listen to the brief story yourself here, presented by journalist Tom Feilden. (I have clashed with him about dinosaur journalism before.) The upshot is that dinosaurs should be shown wading through prehistoric lakes, not walking along the edges of prehistoric forests.

Feilden talks to Brian J. Ford—identified as a cell biologist and with no apparent expertise in paleontology—about why dinosaurs seem to be all wrong. Ford is given relatively little time to explain himself, but insists that dinosaurs were simply too big to have walked on land. “The tail of a dinosaur could weigh ten, twenty tons,” Ford says, which isn’t a precise statement or one that seems to be derived from evidence. Let’s assume that “a dinosaur”—which dinosaur is unclear—had a 20 ton tail. To put this in perspective, in his revision of Brachiosaurus, sauropod expert Mike Taylor estimated the huge Giraffatitan to be about 23 tons in life. Ford is suggesting that some dinosaurs had tails about as heavy as an absolutely huge sauropod, but not surprisingly, where he is drawing this information from isn’t mentioned. Things don’t get better from there.

To Ford, dinosaurs must have lived in perpetually flooded habitats. His whole argument boils down to “Dinosaurs look big!” A popular-audience article in Laboratory News gives Ford some additional space to spell out his ideas, though this does the reader little good. Dinosaurs were big and had heavy tails, Ford tells his audience, ergo, they make no sense on land. That’s it—that’s the whole basis for his speculation. Ford does not appear to have reviewed any of the literature on dinosaur biomechanics or body mass. He just flatly says that dinosaurs, as often depicted, aren’t right. Or as Ford succinctly frames his idea in the final paragraph, “Dinosaurs look more convincing in water.”

I would be remiss if I didn’t point out that Ford isn’t just talking about sauropods. He applies his idea to all large, multi-ton dinosaurs, and goes so far as to suggest one of the strangest ideas I have ever heard for the relatively small forelimbs of tyrannosaurs. Again, Ford uses an aquatic environment as an answer. “The fact that the limbs became foreshortened is entirely reasonable,” he wrote, since “animals like to inspect their food as they eat, and holding it closer to the face is normal behaviour.” Imagine a submerged Tyrannosaurus, trying to peer down at a fish in its arms. If you have ever looked at a tyrannosaur skeleton at all, you can see how downright silly this is. Tyrannosaurus would have to strain its neck pretty hard to get even a glance at whatever it might try to hold in its two-fingered hands. This is the sure sign of a rather crummy idea—the idea is not only unscientific, but it attempts to answer almost every question about dinosaur evolution, biology and extinction.

And there’s an important fact Ford totally missed in his position piece. While he criticizes interpretations of the dinosaur track record, Ford doesn’t mention that there are actually rare traces of dinosaur swim tracks. The majority of dinosaur tracks indicate that the animals primarily lived on land,  but some dinosaurs, primarily medium-sized carnivores, sometimes went into the water. If dinosaurs really did live in water, we’d expect to see many more swim tracks in the fossil record, but these trace fossils are a rarity. We know the kind of tracks dinosaurs left on land, and we know what kind of tracks at least some made in water. Based on the track evidence, Ford’s idea immediately sinks.

Ford’s ideas are zany. That’s not a crime. There are plenty of weird ideas about prehistoric life around the web—the idea that tyrannosaurs hugged trees to hide from prospective prey is probably my favorite nonsense idea. But Feilden did not do his due diligence as a journalist. He reported this story as if there actually was a shred of merit to it, when all that was behind the story was a cell biologist who entirely ignored paleontology. Ford’s comments seem to stem from watching Walking With Dinosaurs—there’s no indication that he has carefully researched the subject he pontificates upon. (In searching for depictions of dinosaurs to criticize, Ford takes an image created for a creationist website as the best science can offer. Oops.) As paleontologists Mike Taylor and Dave Hone have already pointed out on their blogs, there’s not even really a discussion worth having here. Ford presents no actual evidence for his claims, and Feilden uncritically ran with the unsupported assertions.

To his credit, Feilden spoke to dinosaur expert Paul Barrett at the Natural History Museum for a second opinion, but that’s small consolation in a story that didn’t deserve the attention it received in the first place. If there is a story here, it’s about how a cell biologist arrogantly ignored the evidence collected over decades in a different field in an attempt to foist his own just-so stories on dinosaurs to ease his own discomfort at seeing landlubber Diplodocus. Even worse, Feilden makes a connection between the dissenting Ford and Galileo—Galileo, for crying out loud—to hint that Ford’s idiosyncratic views, unfettered by the problem of actually looking at the evidence, may turn out to be right. No. Just no. The accumulated tonnage of evidence places dinosaurs as primarily terrestrial beings, and simply ignoring all of that for the sake of controversial isn’t amazing news. It’s bad science communicated by bad journalism.

Riley Black | | READ MORE

Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Scientific American.