I sometimes like to think about what discovering Pteranodon must have felt like. What, exactly, is the reference frame for a fish-eating flying reptile with a 20’ wingspan? The biggest dinosaurs might have been mind-bogglingly huge, but at least they weren’t expected to do an aircraft impression. The largest flying bird on the planet, the wandering albatross, is barely half the size of an adult Pteranodon. They’re hard enough to picture even if you’ve grown up on palaeontology books; imagine the shock you’d feel if you were surprised by one.
It’s very possible that the palaeontologists who first unearthed Pterandon in the western United States didn’t think much about this sort of thing. They were, after all, engaged in a war. Edward Drinker Cope and Othniel Charles Marsh were the two lead men of 19th-century American fossil hunting, each striving to outdo the other in discovering as many dinosaurs and dinosaur-adjacent critters as possible and each entirely willing to bribe and steal their way to preeminence. This ended unhappily for both Cope and Marsh — conducting a palaeontological war is expensive business — but it did bequeath an enormous quantity of information to science.
For the record, Pterandon was first described by Marsh’s camp. But Cope found it too. In fact, if you’re in the right areas and looking at the right rocks, it’s hard not to find Pteranodon specimens: there have been more than a thousand of discoveries made in the last century or so. Why are these fossils so common?
It’s partly to do with lifestyle. Due to the mechanics of fossilisation, creatures that live in or over the sea have a much higher chance of being preserved, and Pteranodon’s main diet was fish from the Western Interior Seaway, a shallow sea which covered much of the present United States about 70 million years ago. It’s also partly to do with abundance. There were a lot of Pteranodon about back then.
One of the species they shared the coasts with, incidentally, was a smaller pterosaur called Nyctosaurus. I bring up Nyctosaurus mostly so that we can all share a laugh at its ridiculous head.
When I was a kid, Pteranodon had lost a little of its lustre. The discovery of of Quetzalcoatlus and the rest of the azhdarchids meant that Pterandon lost its status as the largest-known pterosaur, and more recent research into azhdarchid hunting behaviour has cast some of them — particularly Hatzegopteryx — as giraffes that a) could fly and b) would happily eat you. Seriously, look at this thing. It’s HORRIBLE:
Anyway, let’s put aside the fascinating developments in pterosaur research and return to the late 20th century, which decided to cast Pteranodon as a surface skimmer, using its long beak to snatch fish from the surface, all while remaining on the wing. This is a feeding behaviour seen in modern day birds (e.g. skimmers, which are aptly named). Skimmers are cool, of course, but not spectacular. And an unspectacular Pteranodon is a sad Pteranodon.
Fortunately, in the last few years Pteranodon seems to have gotten far more spectacular, mostly because their proposed feeding behaviour has changed. As scientists have gotten better at understanding pterosaur flight, they’re realised that the reason Pteranodon has had been cast as a skimmer — specifically the belief that it wouldn’t have been able to take off from a swimming position — no longer hold. So it did something else. What?
I think the most exciting proposal is that Pteranodon behaved like a gannet. Y’all are familiar with gannets, I hope. If not, you should be, because they might be the most awesome bird on the planet. They’re not particularly big or scary or anything like that. The cool thing about gannets is how they hunt.
Gannets drop out of the sky in perfect diving form, hitting the surface of the water at 100 mph or so and using their momentum to catch fish well below the surface. This is quite difficult to do without dying on impact (this is, in fact, a not-uncommon cause of gannet mortality), and their whole body is built for hitting the sea, with specialised nostrils, shock absorbers, etc. etc.
Cool though those adaptations are, the best thing about gannets is that they hunt in flocks. A flock of feeding gannets is an absolutely apocalyptic show, with stream upon stream of bird-missiles plummeting into the sea. Here’s a video from off the coast of Scotland:
Gannets diving off Noss, #Shetland - always an amazing spectacle for guests to witness on our spring and summer trips. Many thanks to the @TheMousaBoat1 crew. @VisitScotland @PromoteShetland @SeabirdCentre pic.twitter.com/9YtErddX5j— Shetland Wildlife (@ShetlandWild) May 29, 2018
Anyhow. Gannets. They’re cool. What would make them even cooler? If they were the size of small aircraft. If a flock of gannets hunting looks apocalyptic now, imagine them on the scale of Pteranodon. It would look like the end of the world.
Is the Pteranodon-as-diver hypothesis likely? I’m not a pterosaur biomechanicist, so I don’t really know. But it does seem at least vaguely plausible in a hand-wavey sort of way, and since it is both vaguely plausible and extremely cool I think that’s good enough for the verdict. Pteranodons: very good.