The Day of the Dinosaur, and the legend of the regrown sauropod tail

October 17, 2019

Two professionals, hard at work.

After this year’s SVPCA, Vicki and London and I spent a few days with the Taylor family in the lovely village of Ruardean. It wasn’t all faffing about with the Iguanodon pelvis, the above photo notwithstanding. Mike and I had much to discuss after the conference, in particular what the next steps might be for the Supersaurus project. Mike has been tracking down early mentions of Supersaurus, and in particular trying to determine the point at which Jensen decided that it might be a diplodocid rather than a brachiosaurid. I recalled that Gerald Wood discussed Supersaurus in his wonderful 1982 book, The Guinness Book of Animal Facts and Feats. While on the track of Supersaurus, I stumbled across this amazing claim in the section on Diplodocus (Wood 1982: p. 209):

According to De Camp and De Camp (1968) these giant sauropods may have been able to regenerate lost parts, and they mention another skeleton collected in Wyoming which appeared to have lost about 25 per cent of its tail to a carnosaur and then regrown it — along with 21 new vertebrae!

De Camp and De Camp (1968) is a popular or non-technical book, The Day of the Dinosaur. Used copies can be had for a song, so I ordered one online and it was waiting for me when I got back to California.

The Day of the Dinosaur is an interesting book. L. Sprague De Camp and Catherine Crook De Camp embodied the concept of the “life-long learner” before there was a buzzword to go with it. He had been an aerospace engineer in World War II, and she had been an honors graduate and teacher, before they turned to writing full time. Individually and together, they produced a wide range of science fiction, fantasy, and nonfiction books over careers that spanned almost six decades. The De Camps’ writing in The Day of the Dinosaur is erudite in range but conversational in style, and they clearly kept up with current discoveries. They also recognized that science is a human enterprise and that, like any exploratory process, it is marked by wildly successful leaps, frustrating wheel-spinning, and complete dead ends. I was pleasantly surprised to find that the authors were completely up to speed on plate tectonics, an essentially brand-new science in 1968, and they explain it as an alternative to older theories about immensely long land bridges or sunken continents.

At the same time, the book arrived just before the end-of-the-1960s publications of John Ostrom and Bob Bakker that kicked off the Dinosaur Renaissance, so there’s no mention of warm-blooded dinosaurs. The De Camps’ sauropods and duckbills are still swamp-bound morons, “endlessly dredging up mouthfuls of soft plant food and living out their long, slow, placid, brainless lives” (p. 142), stalked by ‘carnosaurs’ that were nothing more than collections of teeth relentlessly driven by blind instinct and hunger. The book is therefore an artifact of a precise time; there was perhaps a year at most in the late 1960s when authors as technically savvy as the De Camps would have felt obliged to explain plate tectonics and its nearly-complete takeover of structural geology (which had just happened), but not to comment on the new and outrageous hypothesis of warm-blooded, active, terrestrial dinosaurs (which hadn’t happened yet).

The book may also appeal to folks with an interest in mid-century paleo-art, as the illustrations are a glorious hodge-podge of Charles R. Knight, Neave Parker, photos of models and mounted skeletons from museums, life restorations reproduced from the technical literature, and original art produced for the book, including quite a few line drawings by one L. Sprague De Camp. Roy Krenkel even contributed an original piece, shown above (if you don’t know Krenkel, he was a contemporary and sometime collaborator of Al Williamson and Frank Frazetta, and his art collection Swordsmen and Saurians is stunning and still gettable at not-completely-ruinous prices; I’ve had mine since about 1997).

ANYWAY, as entertaining as The Day of the Dinosaur is, it doesn’t do much to help us regenerate the tale of the regenerated tail. Here’s the entire story, from page 114:

Sauropods, some students think, had great powers of regenerating lost parts. One specimen from Wyoming is thought to have lost the last quarter of its tail and regrown it, along with twenty-one new tail vertebrae. That is better than a modern lizard can do; for the lizard, in regenerating its tail, grows only a stumpy approximation of the original, without new vertebrae.

That’s it. No sources mentioned or cited, so no advance over Wood in terms of tracking down the origin of the story.

Massospondylus tail with traumatic amputation at caudal 25 (Butler et al. 2013: fig. 1A).

To be clear, I don’t really think there is a sauropod that regrew its tail, especially since we have evidence for traumatic tail amputation without regeneration in the basal sauropodomorph Massospondylus (Butler et al. 2013), in the theropod Majungasaurus (Farke and O’Connor 2007), and in a hadrosaur (Tanke and Rothschild 2002). But I would love to learn how such a story got started, what the evidence was, how it was communicated, and most importantly, how it took on a life of its own.

If anyone knows any more about this, I’d be very grateful for any pointers. The comment thread is open.


  • Butler, R. J., Yates, A. M., Rauhut, O. W., & Foth, C. 2013. A pathological tail in a basal sauropodomorph dinosaur from South Africa: evidence of traumatic amputation? Journal of Vertebrate Paleontology 33(1): 224-228.
  • De Camp, L. S., and De Camp, C. C. 1968. The Day of the Dinosaur. Bonanza Books, New York, 319 pp.
  • Farke, A. A., & O’Connor, P. M. 2007. Pathology in Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology, 27(S2): 180-184.
  • Krenkel, R. G. 1989. Swordsmen and Saurians: From the Mesozoic to Barsoom. Eclipse Books, 152 pp.
  • Tanke, D. H., & Rothschild, B. M. 2002. DINOSORES: An annotated bibliography of dinosaur paleopathology and related topics—1838-2001. Bulletin of the New Mexico Museum of Natural History and Science, vol. 20.
  • Wood, G. L. 1982. The Guinness Book of Animals Facts & Feats (3rd edition). Guinness Superlatives Ltd., Enfield, Middlesex, 252 pp.

8 Responses to “The Day of the Dinosaur, and the legend of the regrown sauropod tail”

  1. oliveunicorn Says:

    I think my Dad may have had the Swordsmen and Saurians book. He was a huge fan of Frank Franzetta’s art.

  2. Matt Wedel Says:

    It’s a fantastic book, well worth a post of its own sometime. Krenkel had a more delicate style than Frazetta, more reminiscent of J. Allen St. John, who was mentor to both Krenkel and Frazetta. I like Frazetta as well, but I’m sad that almost no-one these days remembers Krenkel or St. John. They were titans in their time, and deservedly so.

  3. LeeB. Says:

    The Guinness Book of Animal Facts & Feats had (at least) three editions in 1972, 1976 and 1982; the first not surprisingly doesn’t mention Supersaurus; the second talks about it but without any name given and the third talks about Supersaurus and Ultrasaurus.
    Even the last one talks about them as Brachiosaurids.
    The Guinness Book of Records of 1985 discusses Supersaurus as a Brachiosaurid and mentions an even larger scapula-coracoid being found with no name mentioned; but the 1986 Guinness Book of Records talks about the largest scapula-coracoid as belonging to a Diplodocid and calls it the ‘Ultrasaurus’, it also mentions an Ultrasaurus-type Brachiosaurid from Korea.
    So it looks like Supersaurus as a Diplodocid was starting to filter out by 1986.

  4. Marja Erwin Says:

    The earliest mention of sauropod tail regeneration that I’ve found is in Barnum Brown’s “The Last Dinosaurs” in a 1941 Natural History:

    He says this was discovered at Howe Quarry, so he is probably drawing on personal observation of the remains. I can’t check if any of his other publications from 1935 to 1941 mention this.

    BTW, “moron” was used in eugenics campaigns. I believe Carrie Buck was so classified.

  5. Mike Taylor Says:

    Very interesting, Marja, thank you!

    (Both versions of you comment came through; I deleted the redundant one that lacked the link.)

  6. Asier Larramendi Says:

    Hi Matt,

    This is out of topic but here you go:

    I have a doubt with ASP (Wedel 2005). You actually estimated the ASP of sauropods vertebrae centra excluding neural spines (Wedel 2005, Table 7.2), but you appear to apply the obtained ASP to neural spines (Table 7.3). However, it is not clear to me if your calculations for neural spines total volumes, actually assumes the extraskeletal diverticula volume, or if you just try to measure the neural spine bone alone. Below your explanation (Wedel 2005, p.218) :

    The volume of air in the neural spines is
    harder to calculate. The neural spines are complex
    shapes and are not easily approximated
    with simple geometric models. Furthermore,
    the fossae on the neural arches and spines only
    partially enclosed the diverticula that occupied
    them. Did the diverticula completely fill the
    space between adjacent laminae, did they bulge
    outward into the surrounding tissues, or did
    surrounding tissues bulge inward? In the complete
    absence of in vivo measurements of diverticulum
    volume in birds, it is impossible to say.
    Based on the size of the neural spine relative to
    the centrum in most sauropods (see fig. 7.2), it
    seems reasonable to assume that in the cervical
    vertebrae, at least as much air was present in
    the arch and spine as in the centrum, if not
    more. In the high-spined dorsal and sacral vertebrae
    (see fig. 7.1), the volume of air in the neural
    arch and spine may have been twice that in
    the centrum. Finally, proximal caudal vertebrae
    have large neural spines but the size of the
    spines decreases rapidly in successive vertebrae.
    On average, the caudal neural spines of
    Diplodocus may have contained only half as
    much air as their associated centra. These estimates
    are admittedly rough, but they are probably
    conservative and so they will suffice for this

    when you say: “the high-spined dorsal and sacral vertebrae (see fig. 7.1), the volume of air in the neural arch and spine may have been twice that in the centrum”

    What are you referring to with “the volume of air”? The air volume inside the neural arch and spine, or the air volume in the neural arch and spine including the extraskeletal diverticula?

    Thank you so much!

  7. Matt Wedel Says:

    Hi Asier, You hit on something that I explained poorly in that paper, and I owe you (and everyone else) a thorough explanation. I will probably respond in the form of an SV-POW! post so I can illustrate my thoughts, and so there is a convenient place for any following discussion. I haven’t responded yet because I am on a research trip in Utah. Will get home this weekend, and write more soon.

  8. This book is one of the all-too-rare examples of a well-written, well-researched introduction to a broad subject area for the interested layman. Most such books are either aimed at children, poorly-written, or both.

    On a semi-related note, I recently watched the 80s Conan movies (for the first time since the 80s). I was delighted to see L. Sprague de Camp credited as technical advisor on both films. Some-time paleoartist Bill Stout was also involved in the films as production/concept artist. Too bad they didn’t manage to wedge a dinosaur in there.

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