Pathological camarasaurs and carnivorous ceratopsids

September 16, 2008

Want to see something scary?

I mean really scary?

OK, here you go: it’s McIntosh et al. (1996:fig. 31), showing the neural arch and spine of dorsal vertebra 6 of Camarasaurus grandis GMNH-PV 101 in anterior and posterior views:

I’m sure I need hardly point it out, but this neural spine has two badgering great holes in it! What the heck? This feature is seen on both sides of the vertebra, so it can’t be a simple pathology; yet it doesn’t occur in any of the other preserved dorsals (7-12) — nor, indeed, in any other sauropod vertebra known to me, camarasaur or otherwise.

McIntosh et al. (1996:13) see this morphology in terms of “a slender, round rod extending down from the metapophyseal to articulate with the lamina arising from the epipophyseal” — in other words, that the lateral borders of the holes are novel additions to the bone, rather than the holes themselves being novel excavations in the bone — although as we’ve seen before, these things can be a bit six-of-one-and-half-a-dozen-of-the-other. They draw a parallel between this novel strut and the “diagonal ligament” described by Jensen (1988) in “Cathetosaurus” (= Camarasaurus) lewisi, but assert that the struts are bone, not tendon or ligament.

There is, however, a more parsimonious explanation for this novel morpology: as shown here in an actual scientific reconstruction, it appears that this Camarasaurus individual was attacked by a chasmosaurine ceratopsid, and that the skull of the latter become embedded in the sixth dorsal vertebra of the former — the probable cause of death:

[Camarasaurus supremus median dorsal from Cope (1878:fig. 5); Chasmosaurus russeli skull from Godfrey and Holmes (1995:fig. 1b).]

I see this as convincing vindication for Mark Witton’s speculation on facultative carnivory in ceratopsids.

References

  • Cope, Edward Drinker. 1878. On the saurians recently discovered in the Dakota Beds of Colorado. The American Naturalist 12 (2):71-85.
  • Godfrey, Stephen J., and Robert Holmes. 1995. Cranial morphology and systematics of Chasmosaurus (Dinosauria: Ceratopsidae) from the Upper Cretaceous of Western Canada. Journal of Vertebrate Paleontology 15 (4):726-742.
  • McIntosh, John S., Clifford A. Miles, Karen C. Cloward and Jeffrie A. Parker. 1996. A new nearly complete skeleton of Camarasaurus. Bulletin of Gunma Museum of Natural History 1:1-87.
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13 Responses to “Pathological camarasaurs and carnivorous ceratopsids”

  1. Darren Naish Says:

    Ha! That’s all I have to say.

  2. Allen Hazen Says:

    O.k., what’s the scale difference in the two superimposed images. I mean, you have repeatedly emphasized that sauropod vertebrae are big, but Camarasaurus wasn’t the biggest, and ceratopsid skulls are BIG.

  3. William Miller Says:

    Wow. I think this amazing new discovery (interpretation?) deserves a paper. (Horned devils: new evidence for ceratopsians as superpredators; Taylor 2009?)

  4. Nathan Myers Says:

    Hey, that’s no vertebra, it’s a hand puppet!

  5. Mike from Ottawa Says:

    I laughed out loud at “stinkin’ ornithischians”. Sauropods rule the land!*

    * Sorry, but I’m a big fan of pterosaurs for the air and trilobites for the sea.

  6. Mike from Ottawa Says:

    On closer examination, it is obvious the ceratopsian in question isn’t Chasmosaurus. In the ‘vert’ the central spine is thick and the marginal struts thin, while the opposite is the case with Chasmosaurus. Obviously, this fossil not only makes the case for ceratopsian carnivory but also marks the discovery of a new ceratopsian. Not that anyone cares about them, bein’ stinkin’ ornithischians.

    Remember, you heard it here first on SV-POW!

  7. Zach Miller Says:

    It could be a new species of miniature chasmosaurine. Chasmosaurus ittibittius, perhaps?

  8. Jaime A. Headden Says:

    I was actually curious if you were going to bring up Farke’s view on resorption to produce holes in thin membranes of bone, as this appears to be the case in ceratopsians.

  9. Mike Taylor Says:

    Hi, Jaime. I assume this refers to —

    Tanke, D. H. and A. A. Farke. In press [as it was then]. Bone resorption, bone lesions, and extra cranial fenestrae in ceratopsid dinosaurs: a preliminary assessment., in K. Carpenter (ed.), Horns and Beaks, Indiana University Press.

    I’ve not seen that, though, so I can’t comment.


  10. [...] an entry on his blog showing more sauropod vertebrae/ceratopsian frill convergence, as follow-up to our own recent post. Too weird. Posted by Matt Wedel Filed in Sauroposeidon, brachiosaurids, cervical, cross [...]

  11. William Miller Says:

    Does anyone know the cause of this? Reading the other post, it seems not. So this deformity is completely not understood? Are non-sauropod examples known?

  12. Mike Taylor Says:

    As far as I know, it’s never even been noticed before, let alone had a reason proposed.

  13. William Miller Says:

    Wow … never noticed? Not in living animals, either? That’s amazing, and very cool!


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