Ask SV-POW! #1: hollow bones and bitten verts

January 6, 2012

We’re starting the new year with a new feature, in which we answer questions that have come our way. We never had a policy about not answering questions, it’s just that previous ones have tended to arrive in the comments section and have been dealt with there. But suddenly in the last few days I’ve gotten two questions from extrabloggular sources, and rather than hide the replies I thought I’d make them available to all.

One of my cohort at Berkeley texted me the other day with the following questions:

OK, phylobuddy: can you suck the marrow from a chicken bone? If they have hollow bones, where’s the marrow?!? Google is getting me nowhere.

Short answer: yes, one can get marrow from chicken bones, from those bones that contain marrow rather than air. In most fully mature chickens, the pneumatic bones include the braincase, the cervical, dorsal, and most or all synsacral vertebrae, some of the dorsal ribs, the central portion of the sternum, the coracoids, and the humeri (if you’re not a regular and some of these terms are unfamiliar, check out these handy guides [1, 2] to the vertebrate skeleton). That leaves marrow in everything else, although the only bones with large marrow cavities–as opposed to tiny trabecular spaces, which also house marrow–are the radii, ulnae, femora, tibiotarsi, and tarsometatarsi. So if you want to actually see large amounts of chicken marrow, or suck the marrow out of chicken bones, you’re basically stuck with the big distal bones of the wing, the thigh, and the drumstick (tibiotarsus). If you are boiling chicken bones to get stock for soups or stews, might as well throw them all in; even the pneumatic bones will still have bits of adhering meat, cartilage, and ligaments that will give up molecules and flavor to the stock.

The long answer is that the expression “hollow bones” has caused no end of confusion, because there are at least two ways to interpret hollow: filled with air, or not filled with bone (the former is a subset of the latter). If you mean “not filled with bone”, then the bones of almost all amniotes* are hollow, and the spaces inside are occupied by marrow (most commonly) or air. If filled with air, the bones are referred to as pneumatic, and an accessible introduction to them is here.

* At least; I know less about amphibians and fish, although at least one osteoglossomorph (IIRC) pneumatizes its vertebrae from its swim bladder!

The reasons it gets confusing are twofold. First, sometimes authors describe bones as hollow and mean only that they have chambers inside, but later readers see ‘hollow’ and infer ‘pneumatic’. Not all hollow bones are pneumatic; in fact, the vast majority of them are not, including the long bones of your arms and legs. The criteria for inferring pneumaticity from dry bones are more strict, and are explored in this paper and this one. Anyway, this point is just confusion caused by an ambiguous term.

The second case is more interesting, because it involves real unknowns. In the fossil record we can almost always tell if a bone is hollow, sensu lato, but sometimes it is not possible to say for certain whether the hollow space(s) inside were filled with marrow or air. Particularly vexing and intriguing examples include the humerus of Eotyrannus and the iliac chambers of some sauropods, which are discussed in this paper. My guess is that the iliac chambers of sauropods are genuinely pneumatic, because they only occur in sauropods that already have sacral pneumaticity, and we know from broken ilia of more basal sauropods and sauropodomorphs that large marrow-filled chambers are not present in those taxa. Conversely, I suspect that the humerus of Eotyrannus was apneumatic (marrow-filled), given that humeral pneumaticity is otherwise unknown in non-avian theropods, although the pneumatic furcula of Buitreraptor at least shows that the necessary clavicular air sac was present in some.

Next question! This one came to me on Facebook, from ReBecca Hunt-Foster, whom you may know from her awesome Dinochick Blogs. You should also envy her and hubby John Foster for getting the most awesome wedding present of all time: a 1/12 scale skeleton of Apatosaurus sculpted by Phil Platt, which you can read about here. That’s cool enough that I am stealing it for this otherwise picture-challenged post.

ANYWAY, ReBecca wrote on my FB wall today to ask:

Random question: Have you seen many tooth marks on sauro cervical verts? I am debating on whether something I have is a dessication crack or really some tooth marks. Thanks :)

In all the 15 years that I have spent looking at sauropod remains in the bowels of many, many museums, I have never seen a single tooth mark on a sauropod vertebra.

[Update the next day: Er, except for the bitten Apatosaurus tail on display in the AMNH! Many thanks to reptilianmonster and steve cohen for reminding me about this in the comments. I’m going to go hide for a while now.]

Now, that doesn’t mean that they aren’t there. Truth be told, I’ve never looked for them, and my usual mental search pattern for pneumatic traces (large, irregular) would probably exclude tooth scratches (small, linear) as noise. But I’ve certainly never seen any vertebrae with easily recognizable signs of predation or scavenging or with obvious bites removed.

People also sometimes ask me what kinds of healed traumas I’ve seen in pneumatic sauropods bones. That’s easy: apart from vertebral fusions, most of which probably have nothing to do with trauma, I’ve seen zip. Nada. Null set. The wingspan of the average tadpole. I’ve seen some pretty cool pneumatic bones from extant birds that were broken and later healed, including a eagle femur in the UCMP comparative collection that is now shaped like the letter Z, but nothing in sauropods.

I can think of three possible reasons for this, which sort of flow into each other. The first is that apart from the very solid and blocky centra of apneumatic vertebrae, sauropod verts were pretty fragile, and prone to getting distorted and busted up even when they started out intact, and those verts that started out broken just had a tougher time with the taphonomic lottery.

The second is that pneumatic sauropod bones would been nothing to most predators other than a mouthful of relatively dry bone shards, so either carnivores left them alone, or if they were osteovores like T. rex, they ate the shards and whatever is left over is unrecognizable. I have seen, and mostly ignored, plenty of vert-shrapnel in quarries and in collections, and maybe sharper eyes than mine could have discerned evidence of predation from those bits. To me it mostly looked like trampling, hydraulic transport, erosion, and other mundane ways to explode a vertebra.

The third is that in addition to a preservation bias against half-destroyed verts, there is probably also a collection bias against them. I’m probably not the only one would pass up a few shards of excellence to dig out the complete fibula sitting next to them in the quarry, and I love this stuff. That said, we did get a LOT of blasted vert bits out of the Wolf Creek quarry in the Cloverly, so if you want to pore over sauropod shards looking for tooth marks, visit the OMNH.

And, if you do know of tooth marks on sauropod vertebrae, please let us know in the comments. And consider publishing them, given the apparent vacuum of such things.

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22 Responses to “Ask SV-POW! #1: hollow bones and bitten verts”

  1. ReBecca Says:

    Excellent. Thank you. I am currently scoring our Mygatt-Moore Collection for a extensive taphonomy push we are doing. I have only made it through Mymoorapelta so far, and just started on the allosaurs – I admittedly have been putting off the sauropods because of the size of the verts and time it is going to ultimately take (not to mention the need of extra sets of hands). The reasons you point our are exactly what John and I were discussing earlier. Why would a carnivore want to eat a sauro neck (or even the tail) when you have the lovely middle to munch on?

    I know we have one Apato cervical vert in our MMQ collection that does have a broken Allosaurus tooth preserved with it. I have not yet looked to see if the thing had been gnawed on or if the tooth could have just been preserved adjacent to it. I should know if any of the other sauro verts in our collections have any marks by mid to late summer. John might know if we do or not off the top of his head…

    Thanks!


  2. Right off the top of my head, there’s the marked Apatosaurus specimen at the AMNH with caudals that are scored and some bitten off neural spines.


  3. Oops, I just noticed the question said cervical. Sorry about that.

  4. Matt Wedel Says:

    Right off the top of my head, there’s the marked Apatosaurus specimen at the AMNH with caudals that are scored and some bitten off neural spines.

    Yarf, totally forgot about that one. Is this the one posed with the Allosaurus munching on it? I have to confess, I’ve never looked at it very closely or read up on it. Do you–or does anyone else–know if the specimen is actually bitten, or just posed to look that way?

  5. Mike Taylor Says:

    Side-issue, but a really, really important one. Matt wrote:

    In all the 15 years that I have spent looking at sauropod remains in the bowels of many, many museums, I have never seen a single tooth mark on a sauropod vertebra.

    Now, that doesn’t mean that they aren’t there. Truth be told, I’ve never looked for them.

    Maybe the most important lesson I’ve learned about looking at fossils is how often there’s information there that no-one’s noticed before — because nine times out of ten when anyone looks at a fossil they are looking for some specific feature, as for example Matt is usually looking for pneumatic features. In other words, old and much-examined bones often still harbour surprises.


  6. Yes, that is the specimen posed with the Allosaurus. I’ve not seen the specimen firsthand, but I’ve inquired about it plenty. There is (was?) a magnifying glass at the exhibit positioned over some of the more interesting marks. It was initially discussed in: Matthew, W.D. (1908) Allosaurus, a carnivorous Dinosaur, and its Prey. Am. Mus. Nat. Hist.Jour. Vol. viii, pp. 3-5, pl.1. A couple of papers on theropod bite marks published since have made brief mention of it.

  7. steve cohen Says:

    I’m a layman “fossil explainer” at AMNH. The magnifying glass is still there as well as the teeth marks that are visible on several Apatosaurus verts

  8. ReBecca Says:

    Do you know what quarry it is from reptilianmonster?

  9. Matt Wedel Says:

    ReBecca wrote: I know we have one Apato cervical vert in our MMQ collection that does have a broken Allosaurus tooth preserved with it.

    That is awesome. If the tooth is actually embedded in the bone, you should definitely write it up.

    reptilianmonster wrote: There is (was?) a magnifying glass at the exhibit positioned over some of the more interesting marks. It was initially discussed in: Matthew, W.D. (1908) Allosaurus, a carnivorous Dinosaur, and its Prey. Am. Mus. Nat. Hist.Jour. Vol. viii, pp. 3-5, pl.1. A couple of papers on theropod bite marks published since have made brief mention of it.

    steve cohen wrote: I’m a layman “fossil explainer” at AMNH. The magnifying glass is still there as well as the teeth marks that are visible on several Apatosaurus verts.

    Cool, thanks to you both for the info. I feel like a fool for forgetting this most obvious and famous of all examples! I will update the post.

  10. ReBecca Says:

    ReBecca wrote: I know we have one Apato cervical vert in our MMQ collection that does have a broken Allosaurus tooth preserved with it.

    Matt wrote: That is awesome. If the tooth is actually embedded in the bone, you should definitely write it up.

    Cool, I did not know it was that important. I will take a look at it and make sure we get it written up if that is the case.

  11. steve cohen Says:

    ReBecca – the information on the display card only indicates it is AMNH 5753 collected in Aurora Wyoming.

  12. Mark Ryan Says:

    The apatosaurus remains seen beneath the AMNH allosaurus mount were taken out of Como Bluff near where Osborn and Brown (seen in that iconic picture) found a partial diplodocus skeleton in 1897. Jacob Wortman and Wilbur Knight joined Brown and Osborn that summer and discovered the apatosaurus remains close by. The AMNH sites are located just off the main road (Marshall) where it enters the east end of Como Bluff, and near Bill Reed’s Quarry 9 (Mammal Quarry) and Quarry 10 (where Marsh’s Brontosaurus excelsus was removed). The AMNH allosaurus was found farther west on the north limb of the Como anticline.

    PHOTO

    Como Bluff: Then and Now

    “The early part of the season was spent in opening up the mammal quarry which had been accurately located through the kind assistance of Prof. Wilbur C. Knight and Mr. William Reid of the Wyoming University. Later in the season, during a visit by Prof. Osborn, a skeleton of a large reptile was discovered by Osborn and Brown near the mammal quarry. Work began on excavating this skeleton and had progressed well when toward the end of June Dr. Wortman arrived and took charge of the party. Several weeks later a second skeleton was discovered by Wortman and Prof. Knight a short distance from the first specimen.”

    AMNH annual report for 1897

    http://research.amnh.org/paleontology/reports/1897.html

  13. Mark Ryan Says:

    Slight error. The Allosaurus remains (AMNH 5753) were actually found on the north face of the south limb of Como anticline.


  14. The specimen is 222 from the Bone Cabin quarry. Something that I find particularly interesting in Matthew 1908 is that he mentions “Many of the bones of other herbivorous dinosaurs found in the Bone-Cabin Quarry were similarly scored and bitten off.”

  15. Matt Wedel Says:

    Something that I find particularly interesting in Matthew 1908 is that he mentions “Many of the bones of other herbivorous dinosaurs found in the Bone-Cabin Quarry were similarly scored and bitten off.”

    That is interesting. Maybe bitten sauropod verts are relatively common, and I was just ignorant of it.

  16. ReBecca Says:

    Great! Thanks for the help guys!


  17. I think they really are rare. Going through my pdf collection and scanning with google scholar (without institutional access, unfortunately), I turned up a handful of papers that mention toothmarks on near by elements such as ilia and cervical ribs and there’s more than a couple of papers out there that have frustratingly vague statements about numerous marked elements at sites but then not going into detail about what the elements are. However, as far as papers that explicitly mention toothmarked vertebra are concerned, this is the only thing I could come up with:

    “Diverse tooth marks on an adult sauropod bone from the Early Cretaceous, Korea: Implications in feeding behaviour of theropod dinosaurs”
    In which Paik etal 2011 describe a heavily marked sauropod caudal.

  18. ReBecca Says:

    I need to go back and see what the Mothers Day Quarry looked like. I have that paper somewhere. I know they did more taph than most Jurassic workers these days mention.

  19. Mark Ryan Says:

    “The specimen is 222 from the Bone Cabin quarry.”

    According to W. D. Matthew AMNH 222 was from Como Bluff not from Bone Cabin Quarry. Some of 222 (right scapula, 10th dorsal vertebra, and right femur and tibia) was used in the standing mount of the Apatosaurus, along with parts from AMNH 460 from Nine Mile Crossing, and 339 and 592 from Bone Cabin quarry.

    http://ageofdinosaurs.com/books/dinosaurs_matthew_william_diller_ch05.htm


  20. From the quote in Matthew 1908 “An incomplete specimen of Brontosaurus found by Dr.Wortman and Professor W.C. Knight of the American Museum Expedition of 1897, had furnished interesting data as to the food and habits of Allosaurus, which were confirmed by several other fragmentary specimens obtained later in the Bone-Cabin Quarry.” I misunderstood it to mean that specimen came from that locality as well as the later specimens. Darn.

  21. Cary Woodruff Says:

    ReBecca,
    I’ve been working on Mother’s Day material at the MOR, and thus far I have not seen any elements that have bite marks. Most of Tim’s early material is the MOR material, but the CMC has been collecting there since the mid 90’s, so they hands down have the largest collection of Mother’s Day material. Glenn Storrs could tell you more about the CMC material. And I have to agree with Matt. Out of all the sauropod verts I’ve ever looked at I can only think of a few that had marks, and none were cervicals. We have a set of diplodocid dorsals that all appear to be pathologic, but whether the pathologies were predator or disease produced remains unclear. But thinking in the larger sense, what does the absence of numerous bite marks on cervicals indicate? Does this indirect line of evidence suggest that the neck had diminutive muscle mass or significantly more tendons and ligaments that made the neck less attractive to predators than the limbs and abdomen?

  22. ReBecca Says:

    Cary,

    Thanks, that is good to know. As for the large scale question ‘What does this indicate’ – that might be difficult to prove one way or another. It will be interesting to see what our Mygatt-Moore material looks like.


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