Wrong for the Right Reasons

Outdated restoration of a Protoceratops andrewsi nesting
ground. Painting by Charles R. Knight, 1922.

Flipping through an old dinosaur book from the 1970s or early 1980s can be pretty fun. Nostalgia aside, it's great to see how far the science of paleontology has progressed in just a few decades, and also have a few laughs at the (from our modern perspective) outrageously outdated ideas and reconstructions we find. (David Orr's blog Love in the Time of Chasmosaurs has a great, long-running series covering "vintage dinosaur art" that lovingly pokes fun at some of the mistakes made by past palaeontographers.) Old dinosaur TV shows can be just as good. Last week, Mrs. M recorded a bunch of dinosaur shows for me which were airing on the Science Channel. I hadn't seen any of them before, and didn't realize until I hit play that I was in for a blast from the past. The shows were obviously old-school, narrated by Jeff Goldblum (I assumed these had come out around the time of The Lost World: Jurassic Park until one episode started discussing finds from later in the 1990s like Beipiaosaurus). One episode featured a segment on Roy Chapman Andrew's famous discovery of dinosaur eggs in the Gobi Desert, and the infamous misinterpretation of the eggs as belonging to Protoceratops rather than Oviraptor. This is just the kind of paleontological gaffe we paleo fans get schadenfreude out of today. After discussing the refuted hypothesis that an Oviraptor found on a nest of these eggs was first thought to be eating them rather than guarding them as later finds suggested, Mrs. M asked the obvious question: Why, given that this thing was found on top of the eggs, did they assume the eggs belonged to a different dinosaur?


We often look back with hindsight and, somewhat smugly, judge outdated hypotheses as inferior to those of today. We do this because, presumably, our modern notions about how prehistoric animals looked, moved, and behaved are closer to reality. However, 'The Truth' is a tricky concept when it comes to science, and its easy to forget that more than a quest for 'Truth', science is actually a long process of ever-refining hypotheses.

Inaccurate(?) reconstruction of Spinosaurus aegyptiacus as a partially quadrupedal allosauroid-like animal. Painting by Giovanni Caselli, from the book The Evolution of Ecology of the Dinosaurs by L.B. Halstead. Originally posted by Marc Vincent here.

For better or worse, many scientists, even (especially) those who work to popularize science for the lay public, talk about currently-supported hypotheses as if they are The Truth. Ask pretty much any paleontologist to describe, say, a Spinosaurus, and he will likely say it's a bipedal carnivorous and/or piscivorous theropod dinosaur with a tall ridge along its back and a long, crocodile-like snout full of conical teeth. However, Spinosaurus is only known from very fragmentary remains, mainly a few sets of jaws and some vertebrae. So how do we know all this is true? Well we don't, really. That description is a conservative, reasonable hypothesis based on several lines of evidence including comparative anatomy, taphonomy (the arrangement of the fossils in the ground which lead us to reasonably suppose that the jaws go with the verts, rather than coming from different animals), etc. Is it possible that the jaws of Spinosaurus come from a crocodilian with baryonychid-like teeth, while the verts come from an allosauroid? Is it even possible Spinosaurus was actually a quadruped as envisioned by some older reconstructions? Sure. But those hypotheses go above and beyond the current evidence. There is no reason to think those things are true, in favor of the simpler hypothesis that Spinosaurus was a typical theropod with a few weird features. Right now, that's our working version of the truth, and it's the best we've got. If further evidence comes along to prove us completely wrong, great! That kind of dramatic overturning of an accepted hypothesis can lead to some of the most exciting moments in science. But at the moment, it is incumbent on any reasonable person to assume the simplest explanation is the most likely.

So is it really fair to laugh at those silly old scientists in the 1930s who thought Oviraptor was an egg thief that preyed on Protoceratops nests just because it was found near eggs? Just like us and our Spinosaurus, that was actually a reasonable explanation at the time. The eggs were attributed to Protoceratops primarily because there were lots of both. Protoceratops was the most common dinosaur found in the area, so it made sense to attribute the numerous eggs to that genus. The fact that the Oviraptor, known only from the one skeleton, was found associated with one nest seemed likely to be a fluke, which could reasonably be written off as a chance association due to other factors like predation. The scientists who labelled Oviraptor an egg thief were drawing the most logical conclusion they could given the current evidence. The fact that later evidence proved this conclusion wrong doesn't make them foolish--that's how all science is supposed to work. Assuming right off the bat that the Oviraptor was the parent brooding its own eggs would have been an extraordinary claim lacking extraordinary supporting evidence (e.g. embryos or a clearly preserved  brooding posture) and therefore could not be considered justifiable until the discoveries of really extraordinary specimens in the 1990s.

We can take this view all the way back to the earliest reconstructions of dinosaurs. It's well known that those silly Victorians reconstructed theropods and ornithopods as plodding, four-legged, lizard-like beasts. It's easy to overlook the fact that this was actually an entirely reasonable interpretation given the evidence at the time. Bipedal reptiles were unheard of, and anatomical evidence in the early days of dinosaur paleontology led many researchers to conclude that these animals were indeed lizard-like or crocodile-like, if not actual giant squamates. Anyone who suggested to William Buckland that the bones of Megalosaurus may in fact have come from a bipedal animal would rightly have been ignored. They would have been right, of course, but it would have been a position based on a lucky guess rather than good science. Given the scrappy material Victorian scientists had to work with and almost complete lack of closely related forms outside lizards and crocodiles, concluding that Megalosaurus was a basically lizard- or croc-like quadruped with some odd mammal- or bird-like features was the most reasonable thing to do.

Citipati osmolskae embryo in egg.
Photo by Jordi Paya, licensed.

In sciences like paleontology, when somebody says "we know x", this is simply convenient shorthand for "x is the most parsimonious hypothesis given the current evidence." It's usually not necessary to state those caveats unless you're trying to be particularly careful with your wording, because those caveats are the basic underlying principles of science itself. The scientific method doesn't really allow us to ever arrive at 'The Truth', but rather, like Zeno's parodox, we incrementally get closer and closer to truth without ever hoping to reach it. No matter how solid the evidence, those caveats can and must always exist. As reasonable, logical people, we can only accept what we currently know as true, but always with the understanding that more evidence could potentially change that truth. In that light, "truth" in science is always provisional. Even now, we can't say with 100% certainty that the original Oviraptor specimen was brooding those eggs rather than eating them. While we can now recognize the eggs as oviraptorid rather than ornithischian in anatomy, it's always remotely possible that the theropod was raiding the nest of a different species or even another Oviraptor. But given the weight of the current evidence, these assertions are now the unsupportable ones.

So, the next time somebody claims Spinosaurus was a lumbering quadruped mistakenly given the head of a crocodile, you should feel justified in ridiculing the idea as pure fantasy, but don't be too disappointed if it later turns out to have been an incredibly lucky guess.