Saturday, 8 August 2020

The Ridoculus History of Sprawl-legged Diplodocus

Fig. 1: Makin’ my way downtown, crawling fast…

Anyone who is even a bit familiar with old paleoart has probably come across this picture of a sprawl-legged, belly-dragging Diplodocus at one point or another. Anyone reading this blog definitely has, since I am using it as my header-image. It was produced in 1916 by German painter Heinrich Harder for the chocolate company Theodor Reichardt. With each of their chocolate bars came collecting cards of Harderian prehistoric creatures (there exist entire books about the role of trading cards and post stamps in paleoart). Each card was accompanied by an info-text on the back written by Wilhelm Bölsche, a teacher who is credited with inventing the modern “Sachbuch” (informative non-fiction books aimed at laypeople, like the dinosaur books you had as a child). The text on the back of this card just mentions basic facts about this animal, such as the size and the discoverer and that “its posture is controversial”, nothing more. To us today this seems quite perplexing, as the animal looks absolutely ridiculous with its lizard gait. When I showed it to my girlfriend, she said that it looks like it is smiling through the joint-pain, an apt description. How did we end up with this? Also, what if I told you that there exist even more old reconstructions like this, some even sillier?
Fig. 2: An illustration by John C. McLoughlin making fun of old sauropod reconstructions, from the Owenian “cetiosaur” and the Tornerian Sprawlodocus to the swamp-dwelling behemoths which were still prevalent in his time. The first image is however somewhat inaccurate to Richard Owen’s vision, as Owen did not yet know that sauropods had long necks and legs and instead imagined them as cetacean crocodiles.

To begin we have to go back to the early days of sauropod research, which are quite convoluted. When the first known, but fragmentary sauropod remains were discovered by Richard Owen, he believed them to come from a gigantic marine reptile related to crocodilians. He gave it the name of Cetiosaurus as he imagined it as the titanic reptilian version of an orca or sperm-whale that hunted the dolphin-like ichthyosaurs. After more bones were found he corrected its appearance to a dinosaur-like, but still amphibious crocodilian. Harry Govier Seeley and Thomas Huxley finally included the “Cetiosauria” in Dinosauria in 1869, but the damage had already been done and sauropods would be haunted by an association with water and crocodiles for decades to come. A brief departure from this came in 1877 when Edward Cope was able to reconstruct the first fairly complete sauropod skeleton, that of Camarasaurus, thinking of these animals as giraffe-mimics, but even he conceded to the amphibious consensus shortly afterwards. With this context we enter the discovery of Diplodocus carnegiei. It was found and excavated in the years 1899 and 1900 by the Carnegie Institute, who named it after, you guessed it, their patron Andrew Carnegie. In hindsight this was perhaps not the smartest choice, as the animal’s absolutely titanic body being controlled by a most miniscule head was later seen as a perfect analogy for Carnegie’s dictatorial capitalist steel empire (whose workplace environment was so inhuman and social-darwinistic that even Herbert Spencer, a big idol of Carnegie and the inventor of social-darwinism, was appalled by the atrocity which he helped inspire). Nonetheless, the find was a sensation, as not only was it the most complete sauropod, but also the largest land-animal anyone had ever witnessed up to that point. So amazing was the news that Edward VII, King of England, asked Carnegie if he could find another complete Diplodocus and ship it to him. After the Carnegie Institute failed to find a second conplete specimen, Carnegie go the idea of simply creating plaster moulds of every bone of his original fossil and sending the replicas abroad. So he did and sent a DIY-Dippy to London and at least ten other cities around the world, singlehandedly making Diplodocus one of the most well-known dinosaurs. All this time Diplodocus and its sauropod relatives were, unsurprisingly, restored with straight, pillar-like legs like you see in elephants. In fact even Heinrich Harder correctly restored Brontosaurus with upright limbs in 1906. This was not some bold statement of lifestyle or metabolism, but simply a result of paleontological history. In the short time between the discovery of Hadrosaurus foulkii and Camarasaurus it was thought that all dinosaurs (at least those in North America) were bipeds that stood upright like kangaroos. Even early Stegosaurus restorations show it as a biped. When Cope however found Camarasaurus with its long front-limbs he conceded that this must have been a quadruped and simply tilted the kangaroo-pose forward until the hands touched the ground. That this posture evoked elephants and other pachyderm mammals was an unintentional side-effect. When Diplodocus was however first revealed in the British Museum in 1905, F. W. Frohawk was the first to question this convention, as he thought it was unlikely that an amphibious reptile would walk with a mammal-like erect gait and found an alligator-pose more likely. He was however not fully convinced by his own assertion and was simply asking the paleontologists from the Carnegie Institute for their reasoning. Oliver Perry Hay, who was ironically working for the Carnegie Institute, was on the other hand fully convinced that the upright reconstruction was wrong. He argued that the animal, being a cold-blooded reptile, could not have supported its enormous weight on erect legs and instead needed to crawl on its belly with sprawling legs and sideways facing feet. He also argued that, being a swamp-dweller, it would have become stuck in mud with its narrow feet if it stood upright. Thus, he wanted to present us with this vision, which you see further illustrated in fig. 3.:

It seems to the writer that our museums which are engaged in making mounts and restorations of the great Sauropoda have missed an opportunity to construct some striking presentations of these reptiles that would be truer to nature. The body placed in a crocodile-like attitude would be little, if any, less imposing than when erect; while the long neck, as flexible as that of an ostrich, might be placed in a variety of graceful positions.” (Hay 1908).
Fig. 3: Oliver Hay’s Diplodocus. In a strange way this resembles modern reconstructions of the protorosaur Tanystropheus.

German paleontologist Gustav Tornier was fully convinced by Hay’s restoration and so he produced his own skeletal of Diplodocus, trying to make the sprawling posture seem plausible. I have no doubt that Heinrich Harder’s “Sprawlodocus” is based on Tornier’s skeletal. The legs are even in the same walking position, as is the swan-like neck. Tornier’s view became popular among other German paleontologists, who went on to mock the Americans for ever thinking that a reptile would be equipped with the leg-posture of a mammal. Obviously offended by the condescending language, William Jacob Holland of the Carnegie Institute, who had supervised the mountings of the various Dippy replicas, took Tornier’s skeletal and absolutely destroyed it. He showed that Tornier had articulated the skeleton in such a way that almost every bone in the legs was dislocated, which would have caused the living animal unimaginable pain and agony. More importantly, the rib-cage of Diplodocus was deeper than its shoulders, something which was omitted and warped in Tornier’s reconstruction. If Dippy walked with sprawling legs, it would therefore have required to hang its belly into deep trenches to move, something highly inconvenient. Holland sarcastically concluded that if Tornier’s reconstruction was correct, then it was no wonder that this animal went extinct. Furthermore, he also counter-argued Hay’s assertion that Dippy needed sprawling legs to support its weight. In reality, the best posture for supporting great weights in animals is the erect stance, as obviously demonstrated by elephants and other large mammals. The debate was already over by 1920 and incontrovertible evidence for the rectigrade posture was found in the 30s in form of trace fossils. Unfortunately, the idea of sauropods as swamp-dwellers would hold on until the 70s, as even with a proven erect posture it was hard to imagine these animals holding their own weight on land. Thus, the idea of “crocodile-swans” morphed into the hippo-like reconstructions we are more familiar with, but which are equally incorrect.
Fig. 4: Tornier’s Diplodocus skeletal. Notice how severely disarticulated the limb bones are to reach this pose.

Retelling the “Sprawlodocus”-arc was a common trope in dinosaur books from the 70s and 80s, such as Desmond’s The Hot-Blooded Dinosaurs, Bakker’s The Dinosaur Heresies, McLoughlin’s Archosauria or David Norman’s and John Sibbick’s The Illustrated Encyclopedia of Dinosaurs. Most of these like to illustrate the comical image of a sprawl-legged Diplodocus having to do a trench-walk. What is fascinating is that at least in Bakker’s retelling, the story is represented as a fight purely between correct American and incorrect German scientists (Bakker 1986, p. 204). No mention is made of Oliver Hay, the American scientist who first popularized the “Sprawlodocus”. Is this perhaps reflective of the still lingering resentment against German scientists for mocking American ones? Or simply an artifact of simplification? Those are questions for another day.
Fig. 5: A 1985 John Sibbick illustration making fun of the Sprawlodocus and its obvious anatomical flaws. In a recent episode of the Terrible Lizards podcast, paleontologist David Hone for some reason claimed there once were paleontologists trying to look for these "Sprawlodocus-trenches". I have no idea where he got that from, as the idea of Diplodocus having to walk through trenches was always meant to ridicule Tornier's and Hay's reconstructions. It was never a serious suggestion, but a form of sarcastic satire.

Related Posts:

Literary Sources:
  • Bakker, Robert Thomas: The Dinosaur Heresies. New Theories Unlocking The Mystery of the Dinosaurs and Their Extinction, New York 1986.
  • Desmond, Adrian: The Hot-Blooded Dinosaurs. A revolution in Paleontology, London 1975.
  • Mcloughlin, John: Archosauria. A New Look at the Old Dinosaur, New York 1979.
  • Norman, David: The Illustrated Encyclopedia of Dinosaurs, London 1985.
  • Probst, Ernst: Tiere der Urwelt. Leben und Werk des Berliner Malers Heinrich Harder, Norderstedt 2014.

Papers:
  • Frohawk, F. W., 1905. The attitude of Diplodocus carnegiei. The Field, 106, p. 388. For the reply vindicating the Americans for their choice of pose see The Field, 106, p. 466.
  • Hay, O. P., 1908. On the habits and the pose of sauropodous dinosaurs, especially of Diplodocus, Am. Nat., 42, pp. 672-881.
  • Hay. O. P., 1910. On the manner of locomotion of the dinosaurs especially Diplodocus, with remarks on the origin of birds, Proc. Wash. Acad. Sci., 12, pp. 1-25. Plate I.
Further Reading:

Image Sources:
  • Fig. 1: Probst 2014, p. 53.
  • Fig. 2: McLoughlin 1979, p. 64.
  • Fig. 3: Hay 1910.
  • Fig. 4: Desmond 1979, p. 120-121
  • Fig. 5: Norman 1985, p. 186.

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