Wilfarth's Great Tides and the Dinosaurs - Part 3

Go here for Part 2!

And so we continue with Martin Wilfarth and his alien visions for the Mesozoic:

“The herbivorous Kickoff-Breathers”

Die herbivoren Abstossatmer (Iguanodontidae)

…and birds?

Coming now to the Ornithischia. Wilfarth imagines the ancestor of the ornithischians as a small “saltopodid” that adapted to living in more isolated but large tidepools that connect with the ocean only for a short time during flow. Plankton was sparse here, and so were the filter-feeding invertebrates that most of the saurischians fed on. So these small dinosaurs instead began feeding on water plants, which was an easy transition, as he notes, because they are softer than terrestrial plants that have woody support-structures (Wilfarth 1949a, p. 54). As the ancestral, pencil-like front teeth were useless for herbivory, they were lost and instead the lips hardened, becoming eventually a true beak supported by a predentary bone. Hence why Wilfarth sees the name Predentata as equally valid as Ornithischia. Being small animals in deep tidal lakes, made even deeper during flow, the animals needed to jump up a far distance to breathe. Grazing underwater in a crouched position, the pubis was already below the femur and could therefore be used to pull the leg back for a powerful upwards jump (see fig. 2). Exploiting this, the early ornithischians retroverted their pubis so that the pubo-femoral muscle could be used even more effectively to help with jumping. The downside of this was that these ornithischians consequently lost the bipedal balancing function of their pelvis and could only move anymore on land either quadrupedally or by hopping (Wilfarth 1949a, p. 54). But as tidal ranges lowered and carnivorous dinosaurs became a bigger threat, some re-developed bipedalism by evolving the additional praebubis or neopubis bone at the anterior base of the pubis, which picked up again the lost lever-function.   

Fig. 1: Underwater Iguanodon. This is one of my favorite illustrations in the book, because of how well-drawn the dinosaurs are here. There is a nice, scaly texture to them that is strangely lacking in the others. Though I am guessing that was to deliberately invoke iguanas? (Source: Wilfarth 1949a, p. 56).

As already mentioned (see part 1), unlike other workers of his time, Wilfarth did not view the ornithischian pelvis as arising independently from the saurischian one:

“That the ancestor of the ornithischians already was a lever-pelvis saurian, one can see by the retroverted pubis already being true levers, meaning longer than they would have to be for a basket-pelvis. If we count all saurians with a lever-pelvis as dinosaurs, so we may conclude that the ornithischians and birds must descend from a saurischian.” (Wilfarth 1949a, p. 52, translated by me).

Apart from speaking in favour of dinosaur monophyly here, your interest must surely be piqued by the mention of birds. I bet you did not see that coming. Yes, indeed, Wilfarth believed that birds descend from dinosaurs, a fact we all know today but an idea that would have been regarded as highly unorthodox in the 1940s, thanks to Gerhard Heilmann and Othenio Abel, who, contra Huxley, had popularized the idea that birds only share a common ancestor with dinosaurs among the Pseudosuchia. Wilfarth goes even further by claiming that the birds actually descend from the hypothetical small tidal proto-ornithischians just discussed:

“The birds probably branch off at the point on the evolutionary line to the ornithischian at which the retroverted pubis had been gained, but the herbivorous diet has not or not fully been adopted yet. In the birds must then have occurred an arboreal episode in their evolutionary line. The little saurischian who was destined to become the progenitor of the birds then probably climbed up the tree as an insectivore. Here a neopubis was not gained, because here there was no necessity for it.” (Wilfarth 1949a, p. 55, translated by me).

The idea that birds might descend from the ornithischian dinosaurs was semi-popular among some paleontologists of the early 1900s, mostly due to the shape of their pelvis, but was strongly rejected by Gerhard Heilmann (1926) on the basis of the ornithischian pelvis only bearing a resemblance to that of ratites, whose skeletons are greatly derived from those of ancestral birds like Archaeopteryx, as well as ornithischians supposedly not having clavicles that could have evolved into the avian furcula. Wilfarth surely was aware of Heilmann’s writings, given that he heavily references his artwork, so it is interesting that he either disagreed with or ignored these conclusions. Sadly, there is no greater elaboration than what you have just read. Wilfarth was not the only one proposing a bird-dinosaur ancestral relationship during the pre-Ostrom “Dinosaur Doldrums”, but those proposals, made by the likes of Carl Vogt, Robert Wiedersheim and Percy Lowe, were even more unorthodox and therefore taken even less seriously. They suggested that birds are actually polyphyletic, with the flying forms descending from Heilmann’s pseudosuchians or even pterosaurs and the ratites directly descending from the ostrich-dinosaurs. So Wilfarth seems a bit saner in comparison, even if he identified the wrong dinosaur group as the bird-ancestors. The bird-ornithischian link would be revived one last time by Peter Galton in 1970, who, just like Wilfarth, concluded that, while true ornithischians with their praepubis were too derived to have been the direct bird-ancestors, they still could have shared a close immediate ancestor similar to Lesothosaurus. Galton himself gave this idea up by the mid-80s (Norman 1985, p. 193).

Fig. 2: The reversion of the ornithischian pubis was to facilitate better jumps, according to Wilfarth (Source: Wilfarth 1949a, p. 53).

The first specific ornithischian group discussed by Wilfarth are the iguanodonts, whom he interprets as larger versions of the ancestral kick-breathers, though now so large that they merely needed to stand up to breathe. Just as with Plateosaurus and the sauropods, the characteristic thumb-claw of Iguanodon he interprets as another tool for the animals to anchor themselves in the sediment while feeding (Wilfarth 1949a, p. 56). During flow, the animal evaded sharks with its strong paddle-tail, during ebb it ran away from the theropods with its strong hindlegs.

“The Backplate Saurians”

Die Rückenplattensaurier (Stegosauridae)

Dinosaurs usually get the short end of the stick in old paleontological texts, but no group ever gets an end as short as the stegosaurs. With their small brains, supposedly useless, extraneous backplates and mismatched legs, many old writers saw these animals as destined for extinction. It is therefore quite refreshing to see that Wilfarth, in his own weird way, actually shows them quite a bit of appreciation, seeing them as expertly adapted to their supposed habitat. It should be noted that Wilfarth here seems to treat ankylosaurs as a type of stegosaur, probably following Marsh’s original definition of Stegosauria.

Fig. 3: Kentrosaurus using its thagomizer as an anchor against the current (Source: Wilfarth 1949a, p. 62).

Especially the backplates have given many early researchers headaches and there have even been some who claimed they were maladaptive traits, a consequence of genetic degeneracy out of control, with Frederic Brewster Loomis writing in 1905 (p. 842): “With such an excessive load of bony weight entailing a drain on vitality, it is little wonder that the family [Stegosauridae] was short-lived”. Wilfarth sees the plates instead as ingenious hydrodynamic structures, a beneficial adaptation for the intertidal zone (which is at least one step above being aerodynamic). To Wilfarth, stegosaurs inhabited shallow waters with strong currents. Feeding against the current, the backplates helped direct the water, so that it would flow over the back and press the animal down, so it could retain a firm grip to the ground instead of being carried away. (Wilfarth 1949a, p. 59 – 60). One wonders if the spikes on Wiwaxia could have worked like that.

Wilfarth is very open to the thagomizer of stegosaurs and ankylosaurs having been used as a defensive weapon (amusingly more against sharks than against theropods), though he thinks that could not have been its only function. Using Kentrosaurus (written here as “Kentrurosaurus”, which was Edwin Hennig’s preferred spelling to avoid confusion with Centrosaurus), Wilfarth notes that many contemporary reconstructions are wrong in showing the tail-spikes of stegosaurs as pointing straight up (Wilfarth 1949a, p. 58 – 59) and instead were splayed more to the side and pointing back. This is still the preferred view today. Where it gets weird is that Wilfarth asserts that therefore the most likely function of the thagomizer was as an anchor or stake in the sediment, as a further countermeasure against strong currents (Wilfarth 1949a, p. 57 – 58). This extends even to the tail-clubs of the ankylosaurs.

The unusually long hindlegs in comparison to the arms are of course another obvious adaptation towards having to rear up in shallow water in order to breathe. Interesting is here that Wilfarth makes special note of the neck-armour many stegosaurs had, which in his view protected the throat during this vulnerable moment (Wilfarth 1949a, p. 63 – 64).

“The Neck-Shield Saurians”

Die Nackenschildsaurier (Ceratopsia)

The earliest ceratopsians, like Leptoceratops, Wilfarth still interprets as primarily aquatic, on account of their deep, laterally flattened tails, something he does for other dinosaurs too. It should be noted that this was pretty common for paleontologists at the time, especially in regards to hadrosaurs, and it took until the Dinosaur Renaissance for some to point out that the dinosaur tail does not resemble the paddle-tails of crocodilians, especially since the deepest sections tend to be close to the body instead of mid- or end-part of the tail.

Fig. 4: Triceratops gracefully grazing in shallow water. In the background an individual lifts its head above the waves to breathe (Source: Wilfarth 1949a, p. 65).

The forms appearing in the Late Cretaceous he however regards as the dinosaurs with the least aquatic adaptations (Wilfarth 1949a, p. 65). Which of course makes sense, because the Great Tides had greatly diminished by this point. Instead of swimming or living submerged, the ceratopsians were merely waders of knee-high waters, grazing on aquatic plants during flow and otherwise prowling the beaches for other plants during ebb. The characteristic neck-frill Wilfarth interprets as a specific adaptation towards that lifestyle. While he does not go full John C. McLoughlin  he does still view the shield as primarily an attachment site for strong neck and shoulder muscles, allowing the skull to quickly pivot around its ball-and-socket-joint with the spine. This “hinge-skull” or “Klappschädel”, as he calls it, allowed the ceratopsians to efficiently lift their snout above water when they needed to take a breath, again according to Wilfarth’s motto that dinosaurs used elaborate bone constructions in order to save on muscle-work. The question of why they would evolve such an unusual hinge-skull instead of simply repositioning their nostrils like other semi-aquatic animals would do, Wilfarth does not address. On the topic of nostrils, Wilfarth writes on the unusually huge ceratopsian nares, believing that, just as with the sauropods, these must have housed elaborate soft tissue structures:

“The bony nasal opening in the ceratopsians is very big. Despite that, this fact has so far been ignored and reconstructions of the neck-shield saurian have always (with the exception of Lull 1933) drawn them a usual small nostril. These ornithischians have simply always been viewed as Mesozoic replacement-rhinoceroses, and for an only-land animal such a huge nasal opening is of course inconceivable. For a shallow-water-dweller and a hinge-skull-breather however, a huge nasal opening, which can be quickly widely opened and then shut close again, was very important.” (Wilfarth 1949a, p. 67, translated by me).

Semi-aquatic interpretations of ceratopsians have popped up here and there again in the decades following Wilfarth, but, as with most dinosaurs, evidence is abundant that these were purely terrestrial animals. However, the large nostrils that he addresses here still present a mystery for paleoartists to this day. While some still continue to reconstruct them with simple, slit-like nostrils, it has become popular to speculate that they may have housed large, inflatable air sacs, used for visual communication as seen in some birds.

Fig. 5: Triceratops using its headshield as a muscle-lever to lift its huge nostrils above the water (Source: Wilfarth 1949a, p. 65).

The nose horn, Wilfarth sees primarily as a means of protecting the large, fleshy and therefore sensitive nostrils. The brow horns in some species, however, he believes primarily evolved as a means of giving the eyes shade, so that they could look more clearly through the water’s surface (Wilfarth 1949a, p. 69), I guess similar to the wings of a black heron. Though he also goes into detail on how the numerous horns on the ceratopsian skull could also be used in defence against sharks, marine reptiles and theropods (Wilfarth 1949a, p. 69 – 70).

That Wilfarth regards the ceratopsians as the least aquatic dinosaurs is of course interesting if we remember (from part 1) his cryptozoological article on the Sanderson reports from African. Of course he would view these as the dinosaurs most likely to survive into the modern day, as they would be best suited for coping with the loss of the Great Tides.

“The Trunkbreathers”

Die Rüsselatmer (Hadrosauridae)

The hadrosaurs are the one group that Wilfarth has focussed the most on, writing papers on the supposed hadrosaur-trunk as far back as 1938. His hypothesis has notably changed and evolved over the years in response to criticism. Perhaps responding to Sternberg’s critique, where Sternberg erroneously claimed that Wilfarth imagined the hadrosaurs having a trunk like an elephant, Wilfarth writes:

“That is why I name the sub-family Hadrosaurinae here “Peaktrunkers” [Original: Spitzenrüssler], although the term “trunk” is dangerous. All the world immediately thinks of an elephant’s trunk, which is used as a tool for gathering food. This is obviously not what is meant here. The expanded breathing-nose, which is the subject here, is solely used for respiration. Also in length and mobility the breathing-nose cannot compete with the elephant’s trunk. As is often the case, here too the right word is missing for a previously unknown apparition. Nose is too little, trunk too much. There is nothing left but to use the term trunk here, because it has to be emphasized that we are dealing here with significantly more than a nose.” Wilfarth (1949a, p. 74, translated by me).

I believe the closest that Wilfarth imagined here for the hadrosaurs is something like the breathing proboscis seen on the snouts of modern softshell turtles. It should be noted that, for the time, this was pretty much the only unorthodox idea Wilfarth espoused about the hadrosaurs. Other supposed aquatic features cited by him, such as deep paddle-tails and alleged webbing on the hands of hadrosaur mummies, were also used by plenty of other contemporaneous researchers to support an amphibious lifestyle for these dinosaurs. And unlike other researchers, Wilfarth did not relegate the hadrosaurs to the waters because he thought they could only eat soft aquatic plants. He does mention that the complex tooth-batteries in their jaws would have been just as effective in function as the molars of mammals (Wilfarth 1949a, p. 54), which I think is somewhat notable, as that would later become an important talking point in the Dinosaur Renaissance.

Fig. 6: An early, trunk-nosed hadrosaur walking upright across the tidal bottom, feeding on aquatic plants drifting in the water. The pose seems inspired by Charles Knight's original reconstruction of Trachodon (Source: Wilfarth 1949a, p. 74). 

The hadrosaurs he imagines as evolving from an ornithischian similar to Iguanodon, but adapted to the shallow-water conditions of the Late Cretaceous. They no longer needed to rear up or fulfil breath-jumps in order to breathe and instead, convergently to the ceratopsians, evolved adaptations that allowed them to keep their nostrils above the water during feeding. The simplest of these forms were the aforementioned “Spitzenrüssler”, Hadrosaurinae, to which Wilfarth counts forms like Hadrosaurus (synonymous to him with Trachodon), Edmontosaurus and Claosaurus. These differed from the iguanodonts by having deep, vacuous nares, which Wilfarth again sees as an indicator for elaborate soft-tissue structures, in this case an inflatable, short, forward-facing proboscis. That these spaces probably did house some sort of elaborate nostril structure is still a popular speculation today, though, as with the ceratopsians, something like inflatable display sacs were probably more likely. Wilfarth makes special note of the hook-like squamosal bones at the back of the skull of hadrosaurs, which he interprets as a lever-like structure, again similar to the ceratopsian neck-frill, that allowed the animals to quickly clap back their heads for quick breaths (Wilfarth 1949a, p. 83). The zygapophses in the neck vertebrae he interprets as a further stabilizing feature to better make the animal withstand strong currents (Wilfarth 1949a, p. 82 – 83). The general feeding mode of hadrosaurines he imagines as walking bipedally through shallow water and feeding, from below, on drifting plants on the water’s surface.

Fig. 7: Wilfarth's supposed evolution of the hadrosaur trunk. Beginning with forward-facing, extendable nostrils in Claosaurus, pointing backwards in Kritosaurus, becoming a large, fleshy structure in lambeosaurines, before then ossifiying in Parasaurolophus. As the description indicates, Wilfarth was unsure where the fleshy nostrils would have actually connected with the inner skull, speculating if a secondary opening atop the skull was a sort of new naris (Source: Wilfarth 1949a, p. 85).

With the water constantly splashing against the nose, the trunk eventually began facing backwards and started to retract, as seen in supposed transitional forms like Kritosaurus. This eventually resulted in the evolution of the “Helmettrunkers” (Helmrüssler), the Lambeosaurinae. In Wilfarth’s view, the headcrest on animals like Corythosaurus was the basis for fleshy trunk extending from the top of the head, allowing the animal to feed on plants and breathe in water even in a crouched-over position. Wilfarth remains ambiguous on where he thinks the connection of the fleshy nostrils into the skull would have run. In his sketches he seems to prefer a secondary skull opening in the crest he labelled 5b, but as he cannot find it in every hadrosaur skull, he is also open to the trunk having been connected to the original nares at the front of the snout (Wilfarth 1949a, p. 85), which would seem much more sensible if you asked me.

Fig. 8: Corythosaurus in breathing and feeding position (Source: Wilfarth 1949a, p. 78).

The end-point of this evolution were then eventually forms like Parasaurolophus. The idea that Parasaurolophus’ famous headcrest acted as a form of snorkel is not actually unique to Wilfarth. Alfred Sherwood Romer, yes that Romer, in his famous textbook on vertebrate paleontology, already had this idea in 1933. Though without any fleshy bits, instead thinking there must have been an actual hole at the end of the crest. Wilfarth’s original interpretation was ironically very different. In his 1938 paper on hadrosaurs, he originally speculated that the whole headcrest of this dinosaur was connected by muscles and ligaments to the neck and shoulders, acting similarly to the hinge-skulls of the ceratopsians. This was of course an extreme interpretation he was strongly criticized for (Wiman 1942), though it is interesting from the perspective of the modern discussions on the placement of the nuchal ligaments, such as in Bertozzo et al. 2020. Shortly after publication, Wilfarth gave this idea up (Wiman 1942), so I guess you at least cannot say that he was not receptive to criticism.

Fig. 9: Parasaurolophus, able to breathe and feed at the same time thanks to its crest (Source: Wilfarth 1949a, p. 84).

Instead, again following the idea that dinosaurs preferred replacing muscle-work with bone construction, the crest of Parasaurolophus actually represents an ossification of the breathing trunk that in forms like Corythosaurus was still made out of flesh and muscle (Wilfarth 1949a, p. 82 – 83). This made it the most specialized and efficient of the hadrosaurs, able to feed in shallow water, even on all fours, while being able to breathe at the same time. But even that did not save it from extinction.

The Great Dying

Wilfarth’s assessment of the End-Cretaceous mass extinction is as brief as it is succinct and his evaluation of different hypotheses reads as surprisingly modern, systematically going through all the ideas that were popular during his time before coming to his own conclusions. Funny for us today is that he labels it the Great Dying, which is now a term more reserved for the End-Permian mass extinction.

First Wilfarth addresses the idea that competition with mammals wiped out the dinosaurs, something proposed, for example, by Baron Franz Nopsca. He, quite correctly, counters this with the remark that dinosaurs were not the only animals that went extinct and that mammals could have hardly also been competing with the marine reptiles and pterosaurs.

Next is the idea that disease could have been the main cause, an idea first championed by Roy Lee Moodie and long after even by Robert Bakker. Here again, Wilfarth notes that epidemics could have hardly wiped out both the dinosaurs and also all the other giant reptiles, as well as so many invertebrates like ammonites.

Third is the idea of “racial senility” or “phylogeronty”. This was an idea very popular in the early 20th century, endorsed by some leading paleontologists like Richard Swann Lull and Arthur Smith Woodward, who claimed that whole lineages could “age” like a single person, meaning that the longer they existed the more their genome would deteriorate and grow out of control, leading to the evolution of maladaptive features and eventually extinction (Benton 1990). Proponents of this idea often liked to point at the odd and excessive features on the skulls of dinosaurs, like the hadrosaur headcrests or the ceratopsian neckfrills, or at the strange shell-shapes of the heteromorph ammonites, as evidence that the genetics of these animals had gone awry with age, like the Ottomans and Byzantines growing more decadent as their empire neared its end (Bakker 1986, p. 52). That this idea was once so popular, and that it still subconsciously lingered on in popular imaginings of prehistory long after, is pretty baffling, as it falls apart when you think about it for just a minute. All life on Earth shares the same common ancestor, so at any point in time all lifeforms also share the same evolutionary age of their genes. Wilfarth, who we have seen views all the odd features of dinosaur anatomy as beneficial adaptations for their lifestyle, points exactly this out when he criticizes the concept of racial senility and asks why the dinosaurs should have grown senile, but crocodiles, snakes, lizards and turtles still have not. Adding to that: “Should this senility have extended to the ammonites and so on? Lingula, a brachiopod, has from the Cambrian until today not grown senile” (Wilfarth 1949a, p. 87, translated by me).

The fourth idea he addresses is that other animals ate all the dinosaur eggs. Here he correctly points out that it would be highly unusual for the number of egg-eaters to increase so suddenly and also the obvious fact that many of the marine reptiles did not even lay eggs but gave live birth.

Fifth is the idea that a sudden drop in global temperatures could have led to the extinction of the various cold-blooded animals, which was an idea that would prove to be popular all the way into the 1970s (Benton 1990). Here, Wilfarth brings up the pretty valid point that the early Cenozoic was still just as tropical as the Mesozoic (Wilfarth 1949a, p. 87) and that by the same logic there should also no longer be any snakes and crocodiles today. Indeed, today we know that the Palaeocene and Eocene were actually even warmer than the Cretaceous.

Last, he comes to the also popular idea that orogenies were the main cause, the many new mountain chains building up in the Late Cretaceous draining the swamps that the dinosaurs supposedly inhabited. Again, he points out that many animals went extinct that obviously were not swamp-dwellers, but funnily enough he also points out a very valid inconsistency, which is that many of the proponents of this idea did not view certain dinosaur groups, like the coelurosaurs and carnosaurs, as swamp-dwellers (Wilfarth 1949a, p. 87).

 Thus, Wilfarth comes to the conclusion that you probably could have imagined. By the beginning of the Cenozoic, the Moon had drifted away so far from the Earth that it led to an end of the Great Tides and therefore also the unique intertidal ecosystem that used to cover a large part of the continents. Thus, it came to a collapse of the shallow-water planktonic community, followed by an extinction of invertebrates and in turn marine reptiles and, of course, the dinosaurs (Wilfarth 1949a, p. 87 – 88), which were then succeeded by the fully terrestrial fauna of the Cenozoic. Wilfarth ends his book poetically: “The Great Tides formed the dinosaurs, with the Great Tides they also faded.” (Wilfarth 1949a, p. 88).

Fig. 10: How you supposedly get a Parasaurolophus out of a Corythosaurus, with a speculative transitional form (Source: Wilfarth 1949a, p. 80).

Of course, the base assumption, that dinosaurs were intertidal-dwellers, is wrong and today we definitely know that a catastrophic asteroid impact spelled doom for the Mesozoic, but on its own, Wilfarth’s conclusion is quite sober, especially compared to the other ideas of the time. Why? Because, normally, the biggest driver for the extinction of species is habitat loss, a fact that is more relevant today than ever. While I think human activity certainly was a factor in the extinction of the mammoth, what is often overlooked is that the entire biome these animals inhabited, the mammoth steppe, is also almost completely gone due to climatic and ecological changes.

On another note, it is interesting that Wilfarth here unknowingly tried to resurrect arguably the first hypothesis for the K-Pg mass extinction. Georges Cuvier (1825) was one of the first naturalists of the early 19th century who recognized a major faunal change between the Secondary and Tertiary ages. However, dinosaurs were barely known by that time and so most of the lifeforms known to him from the Age of Reptiles were plesiosaurs, crocodiles, ichthyosaurs and turtles. So he thought that during this period most life was still aquatic or amphibious and went extinct due to a sudden drop in sea levels, with the mammals of the Tertiary Age being Earth’s first true dry-land fauna. How Cuvier and his ilk imagined their alien Age of Reptiles would be a topic for a whole other series of blogposts, though Mario Lanzas has given a good impression.

Assessing Wilfarth

This ends Wilfarth’s vision of the Mesozoic and the lifestyle of dinosaurs. There are obviously some details I would have liked to know more from him. Like, what was going on on dry land during this time? Is this where the first mammals and birds were biding their time until the fall of the Great Tides? How much more extreme were conditions during the Permian? How exactly do pterosaurs and marine reptiles fit into the Great Tides? Except for an image description there is also a sore lack of any stratigraphical arguments from dinosaur-bearing sites that Wilfarth could have addressed.

But in the end how do we want to evaluate Martin Wilfarth? Obviously, he was quite unorthodox and eccentric and his insistence on the validity of his hypothesis and how it supposedly answers so many questions all at once bears all the hallmarks that we today associate with pseudoscience. And most importantly: He was wrong. At the same time, his hypothesis was based on some true uncertainties of his time and some of the things he used as arguments, such as the supposed aquatic adaptations in sauropods and hadrosaurs, were really not all that different from what leading contemporaneous experts were already claiming. He just dared to go a few steps farther down the aquatic paradigm.

Fig. 11: Wilfarth pointing out the unusually vacuous bony nostrils of Iguanodon and Edmontosaurus, speculating that these must have housed large, unusual, fleshy noses with special functions (Source: Wilfarth 1949a, p. 73).

What I hope I was able to show is that there are also things that can be appreciated about Wilfarth’s body of work. He was one of the few scientists in the 1940s who tried to specialize in dinosaurs, at a time when most vertebrate paleontologists were decidedly neglectful of the group. In a recovering post-war Germany, mind you. In the process, he made some points, which, even if they were ignored by his contemporaries, would prove quite prophetic for later dinosaur research. In Wilfarth’s work we find such prescient ideas, unpopular for his time but very familiar today:

• Dinosaurs were successful, complex animals.
• Dinosaur anatomy was sophisticated and its oddities were efficient adaptations to their environment and lifestyle, not degenerate features brought about by “racial senility”.
• Dinosaurs did not go extinct due to incompetence or due to being inferior to mammals.
• Dinosaurs are monophyletic.
• Birds descend from dinosaurs.
• Dinosaur young changed lifestyle and ecology as they grew up.
• Dinosaurs had stiff backs and balancing tails that worked like a seesaw.
• Plateosaurus was an obligate biped.
• Sauropods held their spine up in a slight concave curve and regularly reared up onto their hindlegs.
• The large nares on sauropod, ceratopsian and hadrosaur skulls were likely supporting elaborate soft-tissue structures.
• Small theropods were fast and agile.
• Large theropods were active hunters.
• Stegosaurs were competently adapted animals, not mistakes of nature.
• The spikes on thagomizers faced sideways.
• The horns on ceratopsian skulls were formidable defensive weapons.
• Hadrosaur dentition was complex and just as efficient as that of herbivorous mammals.

It is true that a broken clock strikes right twice a day, but this is a bit more than that, don’t you think? While Wilfarth’s framework as a whole was wrong, it is nonetheless fascinating that the lens with which he viewed the dinosaur skeleton still was able to make him see some features that much later researchers would discover, while being ignored by his contemporaries. And does that not say something about the philosophy of science? In his famous work The Structure of Scientific Revolutions, Thomas Kuhn argued that the worldview a scientist operates in is more important than the data he works with, as only with a change in worldview can he sometimes see things he would not have seen otherwise (some interpreters of Kuhn have gone as far as arguing that he claimed that when the worldview changes, it is the world itself that actually changes). Wilfarth pointing out features that other contemporaries seem to have ignored, such as the highly unusual noses of dinosaurs, would seem to support this. But another point Kuhn argued is that, due to the crucial unintelligibility or incommensurability between worldviews (“planet” is a very different term for a geocentrist than it is for a heliocentrist), scientists will ultimately diverge and break away from each other with each revolution, producing not a progress towards what we would call truth, but a progress away from a common starting point, akin to darwinistic speciation. If all sciences were nearing truth, he argued, we would see them converge into a single grand unified theory, instead of what we actually see: Each discipline splitting up into more and more sub-disciplines, some of which incompatible with each other (such as quantum physics vs. relativity theory).

Wilfarth’s tidal paradigm is incompatible with the warmblooded paradigm of the thinkers of the Dinosaur Renaissance. But not necessarily incommensurable, as the word “dinosaur” would have meant pretty much the same to a Wilfarth and a Bob Bakker, but not to an Edwin Colbert. And they both also made common observations that the researchers of the older swamp paradigm did not. Is that then not a notable convergence? Like pterosaurs and birds both evolving wings, just in different configurations, due to adapting to the same constraints of aerodynamics? Maybe, contra Kuhn, worldviews can convergently adapt to the same underlying constraints, some adapting better to reality than others, implying that there is some sort of truth that can be progressed towards. Or maybe I am just waxing philosophical again because I don't know how to end this section. Here's a meme:

Fig. 12: And so the cruel king stands there among the tides, enjoying the crocodile cacophony or perhaps just the aquatic ambiance, awaiting the arrival of his gangplank galleon. 

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Related articles:

• Wilfarth's Great Tides and the Dinosaurs - Part 1
• Wilfarth's Great Tides and the Dinosaurs - Part 2 
• The Alien Prehistoric World Trope - Part 2
• The weirdest things people have thought about pterosaurs
• Unorthodox Ideas about Bird Origins 
• Stegosaurus: A History of Reconstructions 
• Paleopods: The myth of the predatory prosauropods that kinda turned out to be true
• "Hawkinspunk" Spinosaurus

Further Reading:

• Alien Planetology 
• A Vast Quantity of Evidence Confirms that Non-Bird Dinosaurs were not Aquatic by Darren Naish
• Dinosaur Sex Lakes, Too Big to Walk and the Bizarre Theories of Brian Ford by C. M. Kosemen

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• Wiersma, Kayleigh & Sander, Martin: The dentition of a well-preserved specimen of Camarasaurus sp.: implications for function, tooth replacement, soft part reconstruction, and food intake, in: Paläontologische Zeitschrift, 91, 2017, p. 145 – 161.
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Stegosaurus: A history of reconstructions

A likely reason for what makes dinosaurs so appealing to us today is that they combine the familiar with the unfamiliar. We can see attributes of giraffes, rhinos, turtles or birds in sauropods, ceratopsians, ankylosaurs and theropods, recombined in ways that feel both alien yet still understandable. However, there is at least one group of dinosaurs that one can describe as truly alien with no modern analogues and those are the stegosaurs. A bird-like tiny head sits on a long neck attached to a massive body, with almost comically disproportionate limbs and a tail that looks more like a medieval weapon than a biological structure. And then there is of course the famous, strangely arrayed backplates and spikes, the likes of which, to paraphrase John Foster, can arguably only be found elsewhere in the lobopods of the Cambrian. The true strangeness of Stegosaurus and its close relatives is something that can be underappreciated at times and nowhere else is this as apparent as when looking back at the history of people trying to piece this animal back together. In many ways, the history of reconstruction of this genus might be a good test case for what might happen one day should mankind ever try to reconstruct multicellular fossils on another planet like Mars.

The earliest years with Stegosaurus armatus

The first known remains of a Stegosaurus (YPM 1850) were described by Othniel Charles Marsh in 1877, during the midst of the infamous Bone Wars. The material, uncovered by Arthur Lakes north of the town of Morrison in Colorado, was highly incomplete, mostly consisting of a few vertebrae, other postcranial bones and a single of the famous dorsal plates. There were also teeth and limb bones assigned to the specimen, but these later turned out to have actually belonged to a Diplodocus and an Allosaurus respectively (Carpenter & Galton 2001). Despite the incompleteness, YPM 1850 was still assigned to be the holotype of a new dinosaur species, Stegosaurus armatus, because Marsh was Marsh and the Bone Wars were the Bone Wars. The genus name Stegosaurus means “roofed lizard” and derives from Marsh’s initial interpretation of the animal. He believed that the backplates of the animal were similar to those of the Cretaceous stem-turtle Atlantochelys and thus interpreted them as lying flat on the back like roof-tiles to form a carapace (Marsh 1877). What later turned out to be tail-spikes were also initially interpreted as part of the dorsal armor, perhaps sticking out between the plates. Marsh’s initial vision of the animal was a sort of turtle-like dinosaur that lived mostly in water, but when coming out on land would walk bipedally. The latter idea derives in part from the disproportionate length of the limbs (though mind you some of these came from an Allosaurus, as mentioned), but also because it was commonly thought between the 1860s and the 1870s that all dinosaurs were bipeds, as the most complete dinosaur skeletons up to that point were those of Hadrosaurus and Dryptosaurus (Laelaps). Only in the same year as Marsh’s description was it made apparent that some dinosaurs were indeed quadrupeds, when Edward Drinker Cope sketched the first skeletal for Camarasaurus.

Fig. 1

Marsh provided no restoration for YPM 1850. The first known artistic depiction of Stegosaurus instead appeared in the 51st issue of the Scientific American, on the 29th November of 1884. The illustration was made by a certain A. Tobin, whose full name and further information I have unfortunately never been able to uncover. The article the above illustration appeared in was not about Stegosaurus specifically, but about dinosaurs in general and advances in paleontology, as such there is not much information behind the reconstruction and the purpose of the image was simply to show readers of the time what dinosaurs were like in the flesh. Tobin seems to have based it roughly on Marsh’s initial description, though still has taken some liberties. The dinosaur is presented less turtle-like and instead fairly lean, with an outline and posture more typical of other dinosaur depictions at the time. This is very apparent thanks to the other dinosaur standing behind it (which the description in the article identifies as Compsognathus, which is very strange, as not only were the two genera geographically separated from each other, but Compsognathus was only about the size of a chicken). What is notable and perhaps prescient about Tobin’s depiction is that it shows at least some of the plates sticking out of the skin instead of lying flat on top. Though this may also be coincidental to create a tail similar to that of a crocodilian. 

Edit from 2023: As kindly pointed out by fan of the blog Zain Ahmed, after I had written this post a new paper has been published by Eric Buffetaut in the journal Historia Natural, which sheds some light on the many oddities about "Tobin's" Stegosaurus. It did in fact not first appear in the Scientific American and the artist's name was not even Tobin! The above image first appeared in a paper written by French paleontologist Henri Emil Sauvage (interesting nominative determinism there) which was published on October 11th 1884 in a short-lived popular science magazine named Science et Nature. As it turns out, the full name of the illustrator was Auguste Michel Jobin, a scientific illustrator who has made more paleoart that has sadly been forgotten about (though Buffetaut announced in his paper that he will examine it in a future publication). Furthermore, the dinosaur identified in the SA article as Compsognathus was actually labelled as "compsonote" in Sauvage's paper, which is most likely a misspelling of Comptonotus, an old name for Camptosaurus, an iguanodontian that indeed lived together with Stegosaurus in the Morrison. It seems a lot of things have been confused or lost in translation when the image was re-used by Scientific American.

Of Ungulatus, Stenops and the first skeletal

Even before Jobin, Marsh got busy with his stegosaurs. In 1879 already, Lakes found for him several more stegosaur fossils in the famous Como Bluff. Among them was YPM 1853, which was the holotype for the new species Stegosaurus ungulatus. It was a lot more complete than the previous specimen, preserving parts of the skull, many of the vertebrae, limb bones, backplates and tail spikes. In the following years Marsh went on to describe two further species, S. affinis and S. duplex, but these were based off specimens that were either too simple to deserve distinction or are lost today. A breakthrough was made in 1885, when Marshall P. Felch uncovered USNM 4934 at the Garden Park quarry in Colorado. The stegosaur was not only very complete, but fully articulated. This made it the best glimpse into the true anatomy of Stegosaurus up to that point. Based off it, Marsh described it as the new species Stegosaurus stenops in 1877. On a side note, another species was named by him the same year with Stegosaurus sulcatus, based off USNM V 4937. S. sulcatus is rarely talked about but still notable, as it is probably still valid and possibly the only Stegosaurus species that possessed shoulder-spikes similar to other stegosaurs like Kentrosaurus (Galton 2010).

Fig. 2.

Based on all this new information, Marsh published the very first full skeletal of a Stegosaurus in 1891, which you can see above. This is likely also the most well-known illustration of the animal, as it has been reproduced in art and books too many times to count. Despite its prominence, there are many particularities about it that often go uncommented. Firstly, instead of basing it off the skeleton of the largely complete S. stenops, Marsh tried to depict the more incomplete S. ungulatus with this skeletal, filling in blank areas with data from S. stenops and other Stegosaurus. Therefore, this skeletal is a composite of many specimens, which as we will see, would have some grave consequences down the line. Secondly, there is the arrangement of the famous backplates. Marsh had by now realized that they did not lie flat, but instead grew erect out of the skin, as the attachment sites for the skin and flesh were only at one end of the plate instead of one whole surface. However, the way he imagined them to be patterned differed strongly from our modern vision. Marsh interpreted the plates to all grow behind each other in a single line along the spine. Possibly, this is what forced the dinosaur into such a dramatically arched position, as otherwise Marsh could not have fit on all the plates on the back. There is a chance some of you might still be familiar with this arrangement, as Stephen Czerkas briefly tried to revive this idea in 1987, using the arrangement of spikes on modern lizards like iguanas as an argument. While in scientific circles this never went anywhere, Czerkas’ single-plate-line model was still popular enough to become the basis for the Stegosaurus toy in the very first Kenner toyline for 1993’s Jurassic Park (when the dinosaur finally appeared in the movie’s sequel, it thankfully sported the more conventional plate arrangement, but still came with many other problems, including being twice as large as the real animal). Lastly, there is the number of spikes on the tail, which is eight instead of the conventional four. Marsh curiously knew that S. stenops only had four spikes, but thought S. ungulatus had more, as he found up to nine of them with the S. ungulatus holotype. Because the skeleton was mixed together with multiple individuals, Marsh did consider that the spikes were from two or more different tails, but concluded that eight came from a single individual, because his analysis did not consider them to be duplicates (Carpenter & Galton 2001).

Fig. 3.

While quite strange from a modern perspective, Marsh’s first skeletal reconstruction would have a wide-reaching effect. One of them was that it would form the basis for the actual mount of S. ungulatus at the Yale Peabody Museum, which was likewise constructed of multiple individuals. While Richard Swann Lull modified the mount in 1924 to make the plates paired, it did bear eight tail spikes for the majority of its history. The popularity of this skeleton is therefore likely one of the largest reasons why the idea persisted for so long that S. ungulatus can be distinguished from S. stenops by having eight instead of four tail spikes. Today it is thought that Marsh made a mistake in his assumptions and that S. ungulatus really did only have four spikes like its relative (Carpenter & Galton 2001). It is still neat to know this bit of history, as it means that any time you see a Stegosaurus with eight spikes in old paleoart, it is most likely meant to depict S. ungulatus. Another long-lived legacy of Marsh’s comes from his 1896 monograph The Dinosaurs of North America, in which he emphasizes the nervous system (or rather lack thereof) in Stegosaurus. While Marsh never actually did claim that the hollow cavity in the hip vertebrae was the resting place of a second brain, he suggestively talks about it in strong relation to the small size of the skull’s brain cavity. It was therefore very easy to simplify Marsh’s writing as claiming that Stegosaurus had such a small brain in its skull that it needed multiple nerve centers to operate different parts of the body. Thus was born the unfortunate myth of the butt-brained dinosaur. Today it is thought that the hip-cavity instead housed a glycogen reserve, as it very much still does in some modern birds.

Fig. 4.

Marsh’s work was shortly thereafter followed by the first life reconstruction of the “new” Stegosaurus with a single plate-line and eight tail-spikes, appearing in the popular book Extinct Monsters from 1893, by H.N. Hutchinson, illustrated by Dutch zoology illustrator Joseph Smit. Differing from Marsh’s skeletal, which had more elephantine limbs, the animal is presented here crawling almost like a lizard or a crocodile and indeed many reconstructions from the late 19th century, such as those of Heinrich Harder, would emphasize the reptilian nature of the animal with such postures. In part, this may have been due to the growing dogma at the time about dinosaurs as a whole being just overgrown lizards, though one can also imagine that this was done in part to also make this almost alien creature seem more familiar.

Fig. 5

A strange intermezzo from the general trend appeared in 1899, with this illustration by Frank Bond under the guidance of a certain W.C. Knight from the University of Wyoming (Gilmore 1914). While the general outline of the body seems to have taken notice of Marsh’s skeletal, the arrangement of the armour is a genuine throwback to his original idea from 1877 of a “turtlesaur”, making this illustration pretty anachronistic. Ironically, it also shows the animal to be more flexible and dynamic than usual at the time and it would take over half a century before someone would consider again the possibility of Stegosaurus being able to rear up on its hindlegs.

Fig. 6

1901 saw perhaps the most classic of the old depictions of the animal, drawn by none other than Charles R. Knight, though under the guidance of Frederic Lucas, at the time a curator for the Smithsonian Institution (Gilmore 1914). Lucas commissioned the painting to portray his new idea that the plates of Stegosaurus were not all aligned in a single line, but instead grew in pairs. Unlike modern depictions, he and Knight thought them to have been arranged in bilateral symmetry, meaning the plates mirrored each other. To give credit where credit is due, most people would probably agree that this was the more intuitive interpretation than what we ended up with today. Long into the early 20th century, Richard Swann Lull would still defend the paired-plate model and, as mentioned, would have the Yale mount display it. A few other notable things about Knight’s first reconstruction are how dark and menacing he drew the animal and how he gave it a hooked beak, something not apparent in the real animal’s skull (which, I personally think, when viewed up close, has actually more of a resemblance to early ornithopod skulls, like Camptosaurus). Despite this, portraying Stegosaurus with an almost eagle-like head would become a minor paleoart trope, appearing most prominently in the first illustrated version of Arthur Conan Doyle’s The Lost World.

Fig. 7.

Less than a year after Knight’s painting, Lucas already revised his model and instead concluded that the plates of Stegosaurus were arranged in an alternating/glide-symmetric pattern (Gilmore 1914), meaning they did not mirror each other but instead formed a distinct left and right side. The main reason for this is that the plates are actually arranged this way in the type specimen of Stegosaurus stenops (which is why the dinosaur here only has four tail spikes). This is also the reason for why this reconstruction remains the dominant one today. While it has been argued that the alternating pattern could be an artefact of taphonomy, the completeness and articulation of the skeleton argues against this and other specimens also show signs of such chirality (Cameron et al. 2016). In the same year of 1901, Lucas commissioned a drawing of this new hypothesis from a certain G.E. Roberts, which is most likely the very first depiction of Stegosaurus in art with an alternating plate-arrangement (Gilmore 1914). Unfortunately, the drawing here is not very good, especially anatomy-wise, and was not widely publicized at the time, only appearing years later, in 1910, in an article for the magazine Outdoor Life (Gilmore 1914).

Fig. 8 & 9.

Thankfully, Lucas commissioned Knight again in 1903 to recreate Roberts’ version, but with a more robust anatomy (Gilmore 1919). This time it was in the form of a miniature wax model. Knight would use this as a basis for a gigantic life-sized model of S. stenops, which was originally produced for and exhibited in the World’s Fair of St. Louis of 1904 (Gilmore 1919). Its exhibition at said World’s Fair is possibly one of the reasons why the alternating plate-model was also the one that became more prominent with the wider public than any other interpretation. After the fair, the model would go to the United States National Museum, where it would accompany the S. stenops skeleton USNM 6531. As I have never been to that museum, I do not know what happened to this model. If you know more about its whereabouts, please tell.

Edit: As a friendly commenter has informed me, "Steggy the Stegosaurus" has thankfully survived to modern day, but has been transferred from the Smithsonian to the Museum of the Earth, in Ithaca, New York State. Thank you Abel Alfonso for this info!

Fig. 10.

In 1915, Charles Whitney Gilmore, who has been a great resource on the early history of Stegosaurus, would create his own little life model of the critter.  It is similar to Knight’s, albeit more gracile and compact.

Fig. 11.

Unfortunately for Gilmore, the only time his model would be referenced was in a newspaper article of the Ogden Standard-Examiner from the 15th of August 1920 (which is NOT April Fools day). Written by a man named W.H. Ballou, who had previously worked as an illustrator for Edward Drinker Cope, the article titled “The Aeroplane Dinosaur of a Million Years ago” seriously proposes that Stegosaurus was capable of not only flexing its backplates, but also using them to glide through the air! How Ballou came to such a conclusion is hard to discern, though the notion that birds descended from dinosaurs was still en vogue at this time and Ballou emphasizes the fact that Stegosaurus was part of the Ornithischia, the bird-hipped dinosaurs. While we today know that birds actually descend from the Saurischia, Ballou obviously did think that there is a close connection (as did others before him) and could therefore have very well concluded that some members of the group could have also experimented with other forms of flight. While obviously ridiculous, the idea did curiously reappear again in 1930 in the novel Tarzan at the Earth’s Core by Edgar Rice Burroughs. Yes, THE Tarzan gets attacked by such “aeroplane dinosaurs” in this story. As far as I know, it is not known if Burroughs actually did read this fairly obscure newspaper article or separately came up with the concept by himself.

The classic years

Fig. 12.

Stegosaurus appeared again in spectacular fashion (and thankfully on the ground) in 1933’s classic King Kong, brought to life by Willis O’Brien in glorious stop-motion. The dinosaur is the first prehistoric animal that the protagonists meet on the island and not only is it presented as larger than life, but also requires a multitude of rifle shots to be brought down. It is notably the last prominent depiction to show the plates being arranged in pairs and likely was based off Knight’s first reconstruction. Instead of a beak it also seems to sport scaly lips. People forgetting that Stegosaurus had a beak of some kind is strangely prevalent in some pop-culture-depictions, with even the Jurassic World movies making this error (made doubly strange with the older The Lost World: Jurassic Park actually getting this detail right). One could speculate that this is intentionally done to make the animal more reptilian (and therefore probably monstrous), as beaks are something associated more with birds, but then again, turtles have beaks too. A genuine lack of even the most basic research might therefore be the more likely reason.

Fig. 13.

1940 saw the next prominent appearance of Stegosaurus in film with Walt Disney’s Fantasia, which I have already written about. As is typical, the animal is presented as downright lardy and ponderous when in a peaceful mood. Notably though, when locked in a fight against a T. rex (which yes, is very anachronistic), the dinosaur is shown being mobile and prominently uses its tail as a defensive weapon. As far as I am aware, this scene is indeed the first time that Stegosaurus is shown using its weapon in this fashion in any sort of media. This was in fact the reason why Stegosaurus was used in this scene over Triceratops (who was originally planned for it) because the animators were very excited at the opportunity of finally showing this dinosaur using its natural weapons in the way scientists thought it did at the time (Culhane 1983). One has to keep in mind that the Rite of Spring segment of Fantasia was also meant to be partially educational, at a time long before actual dinosaur documentaries as we know them existed.

Fig. 14.

Excluding such highlights, the general view of Stegosaurus from the 30s until the early 70s was as the quintessential embodiment of everything “wrong” with dinosaurs, as we can see here on the famous Zallinger mural from 1947: a large mass of fat, muscle and armour, with barely a brain to control this bulk. Due to the disproportion of the dinosaur’s limbs, it was usually interpreted as a very awkward walker, with erect hindlegs and sprawled forelimbs, which made the whole front-portion of the dinosaur low-slung. Together with the bizarre armour and notions of phylogeronty (the idea that groups of animals could age like an individual person and, when too long-lived, degenerate), Stegosaurus was interpreted as a misshapen creature whose evolution had clearly invested in the wrong traits and was then left directionless, destined for extinction.

Fig. 15.

A related view can be seen in the 50s with Czech paleontologist Josef Augusta’s writings, wherein stegosaurs are described “like living, impassable fortresses, like armored battle vehicles of primevally wonderful construction […]” (Augusta 1957). Living in the Cold War environment behind the Iron Curtain, Augusta seems to have been interested in the combative nature of the dinosaur. That this militaristic description is immediately followed by Augusta perpetuating the myth of Stegosaurus being so stupid that it needed two brains, paints this interest, however, in a less glorifying light and might instead be viewed as social commentary on the political environment at the time. This view of Stegosaurus, a beast that invests too much in weaponry and is too stupid to even consider other options (and is thus destined to fail), could easily be interpreted as a caricature of the Soviet Union, the United States or even both at the time. The images accompanying Augusta’s descriptions, made by none other than Zdeněk Burian of course, are largely typical of the time. Unlike most artists before him, though, Burian did pay a lot of attention to the fossil skull, even if, like with Knight, the reconstruction ended up a bit too birdlike. As Zoe Lescaze (2017) notes, depicting the dinosaur from behind was also a bold and unusual decision at the time that showcases how confident Burian felt in his skills.

Growing appreciation and some experimentation

 

Fig. 16.

With the beginning of the 70s also began what we all know as the Dinosaur Renaissance. Renewed fascination and appreciation for the terrible lizards made many researchers reconsider their preconceived notions and this not only led to dinosaurs being seen more as successful, metabolically active creatures, but also gave rise to many quite unorthodox hypotheses about dinosaur anatomy, behaviour and lifestyles. While Stegosaurus continued to be depicted as a rather ponderous animal even during the early years of the Renaissance, its weird features were already subject to new interpretations. The obvious point of contention were again the backplates and the question if and how they could have been used as defence. One of the first of such reinterpretations came in 1975 from a popular book by Beverly Halstead, illustrated by Giovanni Caselli. Halstead not only reverts the arrangement of the plates back to a bilateral one, but also opines that they stuck out to the sides like wings, as he thought that in this position they would act a lot better to deter predators. This idea never caught on, as in this position, there would likely not have been enough muscle- and ligament-support to hold the plates in such a fashion and any theropod smart and agile enough would have probably been able to simply bite the animal’s flanks underneath the armor. To give credit where credit is due, Halstead was also of the opinion that the front legs of Stegosaurus would have been held erect like pillars, instead of bent like in earlier reconstructions, as this makes the most structural sense for such a heavy animal. This idea would go on to become consensus.

Fig. 17.

A year later, Ronald Raul Ratkevich and his illustrator, the one and only John C. McLoughlin, presented an interesting behavioural hypothesis. While keeping the erect and chiral arrangement of the plates, they thought that Stegosaurus defended itself by rolling up into a defensive wheel, the plated back thus forming a spiked wall. This has also never caught on, as theropods would have probably been smart enough to approach the stegowheel from a convenient angle and bite right in the unprotected center. An interesting detail regarding this reconstruction is that, as far as I am aware, it is the only one that also shows the spikes on the tail as being arranged with glide-symmetry. While an interesting thought, this does not seem to have been the case in reality. Another interesting detail is that this is possibly the first reconstruction since Frank Bond’s from 1899 that depicts Stegosaurus as being capable of rearing up bipedally.

Fig. 18.

It would be a disservice to not mention an unusual, though rather influential event in stegosaur research, which is Gary Larson publishing this little comic in 1982. Although merely a silly joke, ever since Kenneth Carpenter used it in a 1993 lecture, the term “thagomizer” has actually become a regular name used by many paleontologists for the tail weapons of stegosaurs and even some other dinosaurs. The bones they work with may be dry, but their humour certainly is not.

Fig. 19.

Not everyone was on board with the Dinosaur Renaissance and especially in popular books older ideas and traditions of illustrations persisted, as showcased by this spread from 1985’s The Illustrated Encyclopedia of Dinosaurs by David Norman. As is pretty obvious, Norman’s skeletal here is basically the same as the one Marsh drew in 1891, just with the plates updated. Despite its often anachronistic nature, the “Normanpedia” would nevertheless go on to be quite popular and influential among younger readers, thanks to John Sibbick’s colorful life reconstructions. Thus the vision of ponderous Stegosaurus still lived on in the popular mind.

Fig. 20.

The next year saw the landmark release of Robert Bakker’s The Dinosaur Heresies, where Bakker gave the animal the full Renaissance treatment. Bakker insisted, like Halstead, that Stegosaurus walked with erect front legs, but also that the animal’s shoulder bones could move independently from the ribcage, as in mammals, giving it more flexibility and making it a more efficient quadruped. Bakker furthermore reinforced the idea that Stegosaurus actively used its tail as a weapon, as the tail, unlike in other ornithischians, lacked ossified tendons, giving it far greater flexibility. The mismatch in length between the hind and front limbs also gave the animal a great ability to quickly circle its behind in the direction of an attacker. These are all ideas still very much supported today (in part because we have actually found thagomizer-spikes deeply imbedded in the bones of allosaurs). However, Bakker also had some ideas that still seem unorthodox today. I already wrote about his hypothesis that stegosaurs regularly reared up on two legs to browse on tall plants. Stegosaurs being facultative bipeds is actually supported today by trace fossils called Garbina from Early Cretaceous Australia (Salisbury et al. 2016). Another interesting idea of Bakker’s, unintentionally echoing Ballou, was that the dinosaur could independently move its plates into a defensive position when threatened thanks to muscles attached at the bases. Although once prominently featured in a popular 90s documentary, this has also never caught on, likely because there is not much evidence for such muscle attachments.

Fig. 21.

The end-point of the Renaissance-era developments could perhaps be represented by this skeletal from 2010 by Gregory S. Paul. While the weirder ideas from the 70s and 80s have not persisted, the dinosaur has still undergone many updates compared to older reconstructions. The tail and head are now held clearly above the ground and the dinosaur strides on erect legs. Paul also bothered to include the fact that Stegosaurus actually had throat armour made of smaller ossicles, something actually known since the discovery of the S. stenops type specimen. Paul has also covered the plates in keratin sheaths, something which was confirmed by skin impressions from close relative Hesperosaurus (Christiansen & Tschopp). In general, it was however still a bizarrely proportioned animal, which was soon about to change.

New girl, new times

Fig. 22.

Since Marsh’s first description of the order Stegosauria, many new species related to Stegosaurus had been found all around the world, such as Kentrosaurus, Dacentrurus, Huayangosaurus, Miragaia, Hesperosaurus and the deceptively named Gigantspinosaurus. These revealed a rather surprising thing, which was that the genus Stegosaurus, despite giving the whole group its name, was actually a quite unusual stegosaur. Most other stegosaurs did not have a such dramatic limb proportions, had dorsal spikes in addition to plates, prominent shoulder-spikes, long necks and in general long-stretched bodies. One thing that someone had to consider, however, was that up until the 2010s nearly all skeletals of Stegosaurus, including the one by Paul from before, were composites of multiple individuals, as most specimens were either not completely preserved or were hard to access for such skeletal reconstructions. The last complete description of the genus was also all the way back in 1914 by Charles Gilmore. This all changed in 2015 with the description of “Sophie” (SMA RCR0603/ NHMUK PV R36730), a specimen of Stegosaurus stenops. Sophie was originally discovered in 2003 in the Red Canyon Quarry and excavated by the team from the Swiss Sauriermuseum. Sophie is the most complete Stegosaurus skeleton known to date and has given many new insights into the actual anatomy of the genus. Most importantly, the skeleton shows that Stegosaurus was not actually all that different from other stegosaurs, as we can see here in Scott Hartman’s skeletal from 2016, based on Sophie. The difference in length between the limbs is not as pronounced as was once assumed, the spine is more evenly horizontal, the chest is shallower and the neck is longer. Though more similar now to its brethren, Stegosaurus still has some unique traits, such as the lack of shoulder spikes (except for S. sulcatus) and the plates running all the way from the head to the tail tip. It also remains the largest member of the Stegosauria.

This is highly unlikely to have been the last chapter of Stegosaurus’ history. The only constant, not just in nature but also science, is change, and there still remain many questions regarding this peculiar creature from so long ago, more removed in time from Tyrannosaurus rex than is humanity. Were the plates just there for display or were they really used in defence? Did Stegosaurus eat from tall plants or was it a low browser? Did it have a low bite force and only ate the softest plant parts or had it a tougher diet? Is the gradual extinction of stegosaurs linked to sinking cycad-populations? Did some stegosaurs survive in India until the End Cretaceous? What were its facial tissues like? Did the beak extend all around the rims of the jaw or did it have lips and cheeks? What colours did it have? Did it care for its young or live in herds? How did it interact with other herbivorous dinosaurs? Is the small size of the brain really indicative of exceptionally low intelligence? How many Stegosaurus species are there really? These are all questions that remain open or are at the very least highly debated. Some may be answered in the future, some may be not. What is sure is that Stegosaurus is and will remain an icon of fascination, even in the (highly improbable but not impossible) case that Hartman's reconstruction will one day be as ridiculed as Jobin's is today.

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• Behind the scenes of the Sauriermuseum, with Victoria the Hesperosaurus

References:

• Augusta, Josef: Tiere der Urzeit, Prag 1956.
• Augusta, Josef: Verwehtes Leben, Prag 1957 (Deutsche Übersetzung von Max Schönwälder).
• Bakker, Robert Thomas: The Dinosaur Heresies. New Theories Unlocking The Mystery of the Dinosaurs and Their Extinction, New York 1986.
• Ballou, W. H.: Strange creatures of the past, in: The Century Illustrated Monthly Magazine, New York, 55, 1897, S. 15 -23.
• Ballou, W.H.: The Aeroplane Dinosaur of a Million Years ago, in: The Ogden Standard-Examiner, 15. August 1920, S. 8.
• Buffetaut, Eric: The first life reconstructions of dinosaurs Stegosaurus and Camptosaurus, in: Historia Natural, 13, 2023, p. 121 - 133.
  
• Cameron, R. P; Cameron, J. A; Barnett, S. M.: Stegosaurus chirality, 2016.
• Carpenter, Kenneth & Galton, Peter: Othniel Charles Marsh and the Myth of the Eight-Spiked Stegosaurus, in: Carpenter, Kenneth (Hg.): The Armored Dinosaurs. Bloomington 2001, S. 76–102
• Christiansen, Nicolai/Tschopp, Emanuel: Exceptional stegosaur integument impressions from theUpper Jurassic Morrison Formation of Wyoming, in: Swiss Journal of Geosciences, 103, 2010, p. 163- 171.
• Culhane, John: Walt Disney's Fantasia, New York 1983.
• Czerkas, Stephen: A Reevaluation of the Plate Arrangement on Stegosaurus stenops, in: In Czerkas/Olson (Eds.): Dinosaurs Past & Present, 2, 1987, Seattle. p. 82–99
• Galton, Peter: Species of plated dinosaur Stegosaurus (Morrison Formation, Late Jurassic of western USA: New type species designation needed, in: Swiss Journal of Geosciences, 103, 2010, p. 187 – 198.
• Gilmore, Charles Whitney: Osteology of the armored Dinosauria in the United States National Museum, with special reference to the genus Stegosaurus, in: Smithsonian Institution United Stated National Museum Bulletin, 89, 1914.
• Gilmore, Charles Whitney: A newly mounted skeleton of the armored dinosaur Stegosaurus stenops in the United States National Museum, in: Proceedings U. S. National Museum, 54, 1919.
• Halstead, Beverly: The Evolution and Ecology of the Dinosaurs, Somerset 1975.
• Lescaze, Zoe: Paleoart. Visions of the Prehistoric Past, Köln 2017.
• Maidment, Susannah Catherine Rose; Brassey, Charlotte; Barrett, Paul Michael: The Postcranial Skeleton of an Exceptionally Complete Individual of the Plated Dinosaur Stegosaurus stenops (Dinosauria: Thyreophora) from the Upper Jurassic Morrison Formation of Wyoming, U.S.A., in: PLoS One. 2015.
• Marsh, Othniel Charles: A new order of extinct Reptilia (Stegosauria) from the Jurassic of the Rocky Mountains, in: American Journal of Science, 3, 1877, p. 513 – 514.
• Marsh, Othniel Charles: Restoration of Stegosaurus, in: American Journal of Science, 3, 1891, S. 179–81.
• Marsh, Othniel Charles: The Dinosaurs of North America, in: Annual Report of the US Geological Survey, 16, 1896, S. 135 - 415.
• Paul, Gregory Scott: The Princeton Field Guide to Dinosaurs, Princeton 2010 (2. Edition 2016).
• Ratkevich, Ronald Raul: Dinosaurs of the Southwest, Albuquerque 1976, S. 56.
• Revan, Ariel: Reconstructing an Icon. Historical Significance of the Peabody’s Mounted Skeleton of Stegosaurus and the Changes Necessary to Make It Correct Anatomically. (Bachelorarbeit Yale University, 2011).
• Salisbury, Steven; Romilio, Anthony; Herne, Matthew; Tucker, Ryan; Nair, Jay: The Dinosaurian Ichnofauna of the Lower Cretaceous (Valangian-Barremian) Broome Sandstone of the Walmadany Area (James Price Point), Dampier Peninsula, Western Australia, in: Journal of Vertebrate Paleontology, 36, 2016, p. 1 – 152.
• Volpe, Rosemary: The Age of Reptiles. The Art and Science of Rudolph Zallinger’s Great Dinosaur Mural at Yale, New Haven 2007.

Online Sources/Further Reading:

• Dinosaurs, in: Scientific American, 51, 29. November 1884.
• PBS' The Dinosaurs from 1992 (part 1 of 4)
• Sophie the Stegosaurus: Your Dinosaurs Are Wrong Synapisode #1
• Scott Hartman's website

Image sources:

• Fig. 1: Dinosaurs, in: Scientific American, 51, 29. November 1884.
• Fig. 2: Marsh 1891.
• Fig. 3: Revan 2011.
• Fig. 4 – 7: Gilmore 1914.
• Fig. 8 – 10: Gilmore 1919.
• Fig. 11: Ballou 1920.
• Fig. 12: King Kong, copyright by RKO Pictures.
• Fig. 13: Fantasia, copyright by Walt Disney Pictures.
• Fig. 14: Volpe 2007, foldout.
• Fig. 15: Augusta 1956.
• Fig. 16: Halstead 1975, p. 63.
• Fig. 17: Ratkevich 1976, p. 56.
• Fig. 18: Wikimedia
• Fig. 19: Norman 1985, p. 154.
• Fig. 20: Bakker 1986.
• Fig. 21: Paul 2010 (2016), p. 249.
• Fig. 22: Scott Hartman's website