Among the numerous weird features of MWC 8028, the Snowmass Haplocanthosaurus, is the extreme biconcave profile of the caudal vertebrae, in which each centrum is basically reduced to a vertical plate of bone separating two cup-shaped articular surfaces. All four available caudals — found in different parts of the quarry, in different orientations — have essentially the same cross-section. For the diagram above, I just copied caudal 3, because it’s the most complete, so I could figure out the thickness and cross-sectional shape of a single intervertebral disc.

I drew a more realistic version, with the first three caudals at approximately the right scale, for our neural canal paper last year:

The first three caudal vertebrae of Haplocanthosaurus specimen MWC 8028 in midsagittal section, emphasizing the volumes of the neural canal (yellow) and intervertebral joint spaces (blue). Anterior is to the right. Wedel et al. (2021: fig. 2B).

It’s a drawing, sure, but it’s based on a true story, because we have CT scans of all the vertebrae (and we’re going to publish them, soon, along with the reconstructed verts). 

(NB: I’m using “intervertebral disc” as a convenient shorthand for “whatever soft tissues filled the joint space”. But I do think it was a big, fat, fibrocartilaginous disc, not wildly different from the ones in the human vertebral column. It’s not totally impossible that there was some combination of crazy thick articular cartilage and a synovial cavity — there is some precedent in extant salamanders and lizards — but that seems way less likely, for reasons I’ll go into in detail elsewhere. Incidentally, the notion is floating around that reptiles have only synovial intervertebral joints, but this is simply false: intervertebral discs are present in some squamates [Winchester and Bellairs 1977] and in the tails of birds [Baumel 1988].)

I should point out that the other specimens of Haplocanthosaurus also have biconcave caudal vertebrae, but the concavities are much shallower. So what we’re seeing in MWC 8028 is an extreme version of something we see in other individuals of the same genus.

Now, because the caudal centra and joint spaces are roughly radially symmetrical, their relative cross-sectional areas, in these mid-sagittal sections, should be good proxies for their relative volumes. You can imagine the generating the volume of a centrum by rotating its cross-section through 180 degrees, ditto for the joint space (ignoring tilt since both the centrum and joint space are tilted). We’ll have this math worked out in more detail in the next paper, along with volumes from the 3D models, but the upshot is this:

The volume of the intervertebral discs is about twice that of the vertebral centra. If we ignore the neural arch and spine and the transverse processes, and focus only on the weight-bearing column formed by the proximal caudal centra and intervertebral discs, that column is 2/3 cartilage and only 1/3 bone. 

Why, tho?

I spent some time brainstorming with Alton Dooley and we came up with a whole slate of hypotheses. We don’t necessarily like any of them very much, we’re just trying to cast the widest possible net, to make sure we haven’t overlooked any possibilities, no matter how remote they might seem. Here’s what we have so far:

Non-biological:

1. taphonomic distortion

Abnormal biology:

2. congenital malformation

3. pathology

Ontogenetic:

4. incomplete ossification (animal died without laying down the ‘missing’ bone)

5. senescence (the ‘missing’ bone was removed by some process related to aging)

Functional:

6. increased or decreased movement between vertebrae

7. weight reduction

8. shock absorption

What else? 

To reiterate, we’re in the hypothesis-generating stage, not the hypothesis-evaluating stage. So we’re not interested in whether any of these hypotheses are likely. (In point of fact, I think the ones we have so far all suck.) We just want all of the ideas that aren’t impossible.

The comment field is open!

References

For this forthcoming Barosaurus paper, we would like to include an establishing photo of the AMNH Barosaurus mount. There are two strong candidate photos which we’ve used before in an SVPCA talk, but since this is a formal publication we need to be more careful about copyright. Here are the photos, which are the property of their respective rightsholders:

This one is hard to find at all, at least using Google’s reverse image search. Whereas this one …

… is sprinkled all over the Internet, but (in all the cases I’ve seen so far) without attribution.

Does anyone have the necessary skills to track down who the rightsholder is for either of these? Thank you!

Matt and I are writing a paper about Barosaurus cervicals (yes, again). Regular readers will recall that the best Barosaurus cervical material we have ever seen was in a prep lab for Western Paleo Labs. We have some pretty good photos, such as this one:

Barosaurus cervical vertebra lying on its right side in anterodorsal view (i.e. with dorsal to the left), showing the distinctive shape of the prezygapophyseal rami.

The problem is that this specimen was privately owned at the time we saw it, and so far as we know it still is. So according to all standard procedures, we should consider it unavailable to science until such time as it is deposited in an accredited museum. (I was pretty sure the SVP has an explicit policy to this effect, but I couldn’t find it on the site. Can anyone?)

So what should we do? All the possible courses of action seem unfortunate.

1. We could go ahead and include photos, drawings and descriptions of these vertebrae in the paper — but that would violate community norms by building an argument on observations that cannot be in general be replicated by other researchers. (For all we know, these vertebrae are now decorating Nicolas Cage’s pool room.)

2. We could omit these vertebrae from the paper, but use the information we gained from examining them in formulating our diagnostic criteria for Barosaurus cervicals — but this would also not really be replicable, plus it would have that horrible “we know something that you don’t” quality.

3. We could act as though these vertebrae do not exist, or as though we had never seen them, writing the paper based only on our observations of inferior material and of the good AMNH 6341 that is not accessible for study or photography — but that would make our characterisation of Barosaurus cervical morphology less helpful than it could be.

4. We could refrain from publishing on Barosaurus cervicals at all until such time as these vertebrae, or similarly well-preserved ones, are available to study at accredited institutions — but that would simply deprive the world of an interesting and exciting study.

Is there a fifth path that we have not seen? And if not, which of these four is the least objectionable?

So this just happened

February 24, 2022

I was on a video call with Matt, talking about a project he’s working on that involves Haplocanthosaurus. A lot of his recent project involve Haplocanthosaurus which is … an OK sauropod. I mean, it’s no brachiosaur. So this is how the conversation went:

Mike: I have bad news for you, dude. Haplocanthosaurus is only one or two nodes away from being a camarasaur.

Matt: Sure, but Haplocanthosaurus is really weird, and Camarasaurus is just basic.

Mike: Your mom’s basic.

Matt: Your mom’s one or two nodes away from being a camarasaur.

 

I was looking more closely at the turkey skeleton from my recent post, and zeroed in on the last two dorsal (= thoracic) vertebrae. They articulate very well with each other and with the first vertebra of the sacrum, with the centra and zygapophyses both locking in so that there can only have been very little if any movement between them in life. Here they are, in right lateral view:

Last two dorsal (= thoracic) vertebrae of a mature domestic turkey Meleagris gallopavo domesticus, in right lateral view.

Before we move on, it’s worth clicking through to the full-size version of this image and wondering at both the quality of modern phone cameras (a Pixel 3a in this case) and the variety of textures on these little bones. There is smooth, finished bone on the sides of the neural spines; very fine pits and bumps on the zygapophyseal facets where the thin layer of hyaline cartilage attached; rougher texture in the parapophyseal facets where thicker cartilage attached; and very rough texture on the ends of the transverse processes, where there was relatively thick cartilage.

And there is, unsurprisingly in a bird, pneumaticity everywhere. In the more anterior vertebra alone (to the right) the photo shows pneumatic openings (from bottom to top) low on the centrum (below the parapophysis), high on the centrum (below the lateral process),  in the hollow between the lateral process, the posyzyg and the centrum, on the lateral surface of the prezygapophyseal ramus, and on the rear surface of the lateral process. There are others that are obscured in this photo, including on top of the lateral process where it meets the neural spine. Here they are, pointed out for you (with the hidden one shown translucently):

Last two dorsal (= thoracic) vertebrae of a mature domestic turkey Meleagris gallopavo domesticus, in right lateral view. Pneumatic openings on penultimate vertebra highlighted with red lines; obscured opening above lateral process shown as translucent.

OK, that was the B-movie. Now to the main feature. The next photo shows the same two vertebrae, folded away from each other so that we see the anterior face of the posterior vertebra (on the left) and the posterior face of the anterior vertebra (on the right).

Last two dorsal (= thoracic) vertebrae of a mature domestic turkey Meleagris gallopavo domesticus. Left: last dorsal vertebra in anterior view; right: penultimate dorsal vertebra in posterior view.

Again, do click through to see the exquisite detail, especially the complex of pneumatic features on the anterior face of the neural spine of the last dorsal (on the left) and on the posterior face of the left lateral process of the penultimate dorsal (on the right).

And … in the articular facets of the centra?

Seriously, what the heck is going on here? It doesn’t make sense  that there would be pneumatic openings in articular surfaces, because by definition something else (in this case the adjacent vertebra) is abutted hard up against then, so there is no way for a diverticulum to get in. For the same reason, you don’t get vascular foramina in articular surfaces because there is no way to get an artery in there. And there is no hint in these vertebrae of channels along either articular surface that diverticula or arteries could  possibly have laid in.

And yet, there those big openings are. What are they?

I discussed this with Matt, in case it’s Well Known Phenomenon that I’d somehow not heard about but it seems it is not. What we know for sure is that these openings are present, and that they are not mechanical damage inflicted during preparation. So what are they?

What else even is there for them to be? What penetrates bone apart from diverticula and blood vessels? Nerves follow the blood vessels, so it can’t be nerves in the absence of blood vessels.

By the way, there are similar but smaller openings in the posterior face of the last dorsal (the one on the right in the photo), but none anywhere else along the postcervical column: not on the anterior surface of the penultimate dorsal, not on the front or back of the sacrum, and not in any of the other dorsals.

One possibility we considered is that the vertebrae were locked together in life and that a pneumatic space inside the centrum of the last dorsal worked right through into the penultimate one. But that doesn’t work: the openings are not aligned. Also, those in the penultimate dorsal are definitely blind (i.e. they do not connect to deeper internal air-spaces) and those in the last dorsal probably are, too.

We do not know what is going on here.

Help us! Is this kind of thing common in turkeys? Have people seen it in other taxa? Do we know what it is?

I closed the last post by claiming that finding the infected bone in Dolly was “a crazy lucky break”. Here’s why:

Another point made by Wood et al. (1992) concerns our perceptions of frailty and robustness. They were talking about archaeological populations, mostly from cemeteries, but the point is equally valid for non-human animals. We could look at Dolly and her infected vertebrae and say, “Ah, poor Dolly, she was too frail to fight off the infection” — implicitly comparing her to the individuals in the three left columns of the cartoon, which either never got sick, never developed lesions, or fully recovered. Or we could say, “Look how tough Dolly was, she must have survived with this infection for years!” — implicitly comparing her to the individuals in the right-most column, which all died too fast to develop lesions in the first place. The heck of it is, we can’t tell those comparison groups apart. Both stories about Dolly are true…from a certain point of view.

As a parting shot, here’s something to think about: a lot of the big mounted sauropod skeletons in museums are from individuals that are not skeletally mature — so they didn’t die of old age — and they also lack any evidence that they were killed by predators or even scavenged. There are some dramatic tooth-marked sauropod bones out there (f’rinstance), but not among the “monographically prominent” specimens like CM 3018 (Apatosaurus louisae), AMNH 5761 (Camarasaurus supremus), and MB.R.2181 (Giraffatitan brancai). I wonder how many of the latter were brought down by disease or parasites, and just don’t have any diagnostic traces of the maladies that killed them? Maybe the world’s museums are full of right-column sauropods.

References

Naturally I was grateful when Cary invited me to be part of the team working on Dolly, the diplodocid with lesions in its neck vertebrae (Woodruff et al. 2022; see previous posts on Dolly here and here). I was also intellectually excited, not only to see air-filled bones with obvious pathologies, but also for what those pathologies could tell us about Dolly and other sauropods. That’s the part of our new paper I want to unpack in this post.

We have a lot of evidence that air-filled bones in birds are a good model for air-filled bones in extinct dinosaurs. And we have several lines of evidence (not just air-filled bones; see Schachner et al. 2009, 2011, 2020) that the respiratory systems of many dinosaurs functioned broadly like those of living birds. But we have less direct evidence than we’d like, so every additional bit of information is welcome.

Diving into Diverticula

In birds, the air-filled bones in the neck and body are connected to the respiratory system by air-filled tubes. These tubes sometimes get called air sacs, in the sense that they are sacs filled with air, but we also refer to them pneumatic diverticula, to distinguish them from the respiratory air sacs in the torsos of birds that ventilate the lungs. Imagine blowing up some rubber gloves and sticking them inside a bird* and you’ll have a pretty good mental model of the system — the inflated ‘palm’ area of each glove is like one of the respiratory air sacs, the air-filled glove fingers are the diverticula, and the rubber material of the glove is the pneumatic epithelium that lines the air sacs and the diverticula alike. 

* Please don’t actually try that.

The cartoon above presents an unrealistically simplified picture of the respiratory system in dinosaurs and birds. For one thing, I omitted the windpipe or trachea — that blue tube going up the neck represents the diverticula that run alongside, and often inside, the neck vertebrae, parallel to the trachea but separated from it by whole sheets of muscle. Also, the cartoon only shows diverticula of the air sacs, but diverticula can also originate from the lungs themselves (see O’Connor 2006: 1211 and Schachner et al. 2020: 16-19). Here’s the actual respiratory system of a pigeon, with the trachea and lungs in pink and the air sacs and their diverticula in blue (Muller 1908 fig. 11):

I think it’s pretty natural to look at that illustration and wonder where the heck the guts go, since it certainly looks like the air sacs are occupying the entire volume of the torso. The answer is that the air sacs enclose the viscera “as do the shells of a nut”, in the memorable formulation of Wetherbee (1951: p. 243), describing the air sacs of the English sparrow.


Fig. 4. Reconstruction of the distribution of pneumatic diverticula in diplodocids and dicraeosaurids. A. Schematic drawing of midcervical vertebra of Diplodocus in left lateral aspect (A1), in dorsal aspect with single neural spine (A2) and in dorsal aspect with bifurcate neural spine (A3). The partitioning of pneumatic diverticula at the lateral surface of the vertebral corpus is hypothetical, based on the strongly divided pneumatic fossae. Schwarz et al. (2007: fig. 4A).

Furthermore, the pneumatic diverticula around the vertebrae in birds are complex, and we are fairly certain that they were also complex in sauropods, because they left so many distinct traces. The most detailed reconstructions of the cervical diverticula in sauropods that I know of are those of Daniela Schwarz and colleagues (2007), as shown above. For what it’s worth, I think those reconstructions are not just reasonable but perhaps conservative; I think there’s a good chance that the diverticular network around the vertebrae was even more complex and extensive. 

The rubber-glove model also lets us see that the diverticula are cul-de-sacs. We know that diverticula can anastomose, or merge, to form networks, and there is a possibility that if diverticula from different air sacs anastomosed, different pressures in those air sacs might allow some air to circulate through the diverticular network. Maybe — the anterior and posterior air sacs fill and empty at the same time, so there might not be a pressure differential to exploit. If air circulates in the diverticula at all in birds, it probably happens in the dorsal vertebrae, where diverticula from different parts of the respiratory system have the best opportunity to anastomose. But the far ends of the diverticular network are always dead ends, and we assume that air diffuses in and out of those terminal diverticula fairly slowly. We’re stuck with assumptions because no-one’s ever checked, experimentally, to determine the rate of diffusion or circulation of air in the diverticula. But it’s hard to imagine much circulation in the terminal diverticula, with no air reservoir or pump at the far end.

Reconstruction of soft−tissues in the neck of Diplodocus. A. Transverse cross−sections through cervical vertebra with bifurcate neural spine in the diapophysis region (A1) and in caudal third of vertebra (A2). B. Transverse cross−sections through cervical vertebra with single neural spine in diapophysis region (B1) and in caudal third of vertebra (B2), dashed outlines representing possible craniocervical extensor muscle analogous to m. biventer cervicis of extant birds or m. transversospinalis capitis of extant crocodylians. Schwarz et al. (2007: fig. 7A-B).

Here’s another great illustration from Schwarz et al. (2007), showing cross-sections of the neck of Diplodocus with hypothetical soft tissues restored. Bone is black, muscle is pink, and the pneumatic diverticula are blue. As this diagram makes clear, the air spaces in the bones are themselves extensions of the diverticula (that much is true regardless of how extensive we make the reconstructed diverticula outside the vertebrae). Instead of smooshing an inflated rubber glove into a duck, imagine smooshing one into a vertebra of a duck — or a Diplodocus — so that all of the empty spaces are occupied by some blobby bit of inflated-glove finger. All of air spaces in the bone would be lined by rubber-glove material, which in this metaphor is the same pneumatic epithelium that lines both the respiratory air sacs and their pneumatic diverticula, outside the bones or inside them.

I get to see this firsthand in the gross anatomy lab in our unit on head and neck anatomy. As we open up the skulls of the cadavers, the air-filled epithelial balloons that fill the sinuses sometimes pull away from, or completely out of, their bony recesses. (I’ll bet I could demonstrate the same thing with the sinuses of a pig or sheep head — I should give that a shot and post the resulting photos or videos here.) The point is, the pneumatic epithelium is in intimate contact with the bone, lining every pneumatic fossa, foramen, and internal chamber; this will be really important later on.

Incidentally, one question I get a lot is whether the diverticula, inside or outside the bones, contributed to gas exchange in sauropods. The answer is, probably not. We know from dissections and histological work on birds that the respiratory air sacs, their diverticula, and the diverticular spaces inside the skeleton are all relatively avascular, meaning that the tissues get enough blood to stay alive, but aren’t specialized for gas exchange. Furthermore, physiological experiments on living birds have shown that about 95% of the gas exchange happens in the lungs, and almost all of the remaining 5% happens in the paired abdominal air sacs (Magnussen et al. 1976), probably because they are so large and so intimately in contact with the guts (Wetherbee’s nutshell metaphor), which are well-supplied with blood. We also know from bone histology that the air-filled bones of extinct dinosaurs are essentially identical to those of modern birds (Lambertz et al. 2018), so there’s no evidence that they functioned any differently.

A simplified diagram of the sauropod respiratory system. What I’ve labeled “air tubes” here are the pneumatic diverticula. Air holes in the vertebrae are also known as pneumatic foramina. The shapes of the lungs and air sacs are speculative, but the minimum extent of the pneumatic diverticula is not–although it could be an underestimate (e.g., diverticula might have gone even further down the tail, and just not left any diagnostic traces on those vertebrae).

A final piece before we get back to Dolly: we know from lots of anecdotal observations, and some actual experiments, that air-filled bones have to stay connected to the outside to form in the first place, and to stay healthy afterward. This is true of both human sinuses and postcranial pneumatic bones in birds, so it’s reasonable to assume that it’s a general feature of all air-filled bones (see Witmer 1997 for lots of relevant citations and discussion). This is a pretty handy thing to know, because if we find an air-filled vertebra way out in the tail, we know pneumatic diverticula of the respiratory system got at least that far. ‘At least’ because pneumatic diverticula can make diagnostic traces on bones, but they don’t always do so. That means that the diverticular network can easily be more extensive than its skeletal traces, but not less so — see Wedel and Taylor (2013) for more on that.

To sum up, we suspect the following things about pneumatic diverticula around the vertebrae of sauropods, including Dolly:

  1. The diverticula were complex, based on the traces they left on the bones, and similarly complex diverticula in birds.
  2. The diverticula were patent, or open, maintaining an open connection to the outside by way of the respiratory air sacs, lungs, and trachea, because that’s how air-filled bones work in living birds and mammals.
  3. Despite being complex and ultimately open to the outside in one direction, the diverticula were cul-de-sacs, with little or no active circulation of air — especially in the neck.

With that in mind, what does the distribution of infected bone in Dolly tell us about sauropods?

Infections and inferences

Here’s another illustration of the respiratory system of the pigeon, this time a dorsal or top-down view, from Muller (1908: fig. 12):

Okay, that was a bit of a bait-and-switch: I promised you Dolly and gave you another pigeon. But that’s only to help you understand this similar cartoon I drew, which represents Dolly’s respiratory system and neck vertebrae, also seen from the top down:

Like the earlier cartoon, this is pretty simplified. For instance, I got lazy and didn’t draw all of the neck vertebrae. In life, Dolly probably had 15 or 16 neck vertebrae, like other diplodocids, and we know that the three with lesions are C5-C7 because they were found articulated. Here I drew just enough vertebrae to make my points, and I left off the head and all the other extraneous bits. Also, I’ve drawn the diverticula that run up the neck originating from cervical air sacs, as in pigeons (Muller 1908), but there is evidence that in ostriches those diverticula may originate from the lungs themselves (Schachner et al. 2020). Whether the diverticula come from the lungs or the air sacs is probably not an answerable question for sauropods, and for my purposes here, it doesn’t matter, only that the diverticula are connected back to the core respiratory system.

Three things struck us about the distribution of the infected bone in Dolly’s neck:

  1. The lesions are all in vertebrae that are a long way up the neck, far from the lungs and respiratory air sacs in the torso.
  2. The lesions are clustered in serially-adjacent vertebrae, instead of being scattered up and down the neck randomly.
  3. The lesions are present bilaterally, on both left and right sides of the affected vertebrae.

Well, as opposed to what? We can imagine a scenario in which the lesions were scattered randomly, not just up and down the neck, but also on left and right sides, like so:

If the infection had been carried in the blood, we might expect such a random pattern. In that case, it would be an extreme coincidence if a blood-borne infection, which could go anywhere in the body, only manifested in the air spaces on the sides of three consecutive vertebrae. The clustering of the Dolly’s lesions, in the air spaces on both sides in three adjacent vertebrae, far up the neck, points to a different cause.

Recall that diverticula are lined by epithelium, and that in air-filled bones, the epithelium is right up against the bone tissue. The infection in Dolly almost certainly started out as an infection in the diverticulum, which was so severe that it spread to the underlying bone. In exactly the same way that the air spaces in the bones are the skeletal footprints of the diverticula, the lesions in Dolly’s vertebrae are the skeletal footprints of infected epithelium lining the diverticula, like so:

The infection may have gotten so severe, far up Dolly’s neck, precisely because there was little airflow so far from the lungs and air sacs. Airborne bacteria or fungal spores could have floated into the diverticula by diffusion, come to rest against the epithelium in warm, dark, humid conditions, and gone wild. It’s also possible that a huge swath of Dolly’s respiratory system was infected, but the infection only got severe enough to spread to the underlying bone in cervical vertebrae 5-7, in which case the actual infection might have looked something like this:

Just like a diverticulum can contact a bone without producing a distinct trace, the pneumatic epithelium could be infected without producing a bony lesion. Thought experiment: how many times have you had a sinus infection, and how many people do you know who have had sinus infections? And how many of those sinus infections were severe enough, and lasted long enough, to produce bony lesions like we see in Dolly? Probably very few — such things do happen in humans, and the medical literature has plenty of cases (and if this has happened to your or a loved one, you have my full sympathy) — but on a population level, the fraction of respiratory infections that produce bony lesions is miniscule. Similarly, it’s very likely that much more of Dolly’s respiratory system was infected than we can tell from the skeleton.

A cervical vertebra of an ostrich with some of the pneumatic diverticula traced on.

The presence of infected bone on both left and right sides of C5-C7 in Dolly is also telling. If the diverticula on the left and right sides of the neck were separate, the symmetrical pattern of infection would be another extreme coincidence. But in birds there are opportunities for diverticula from the left and right sides of the neck to meet and anastomose, especially the supravertebral diverticula on the neural arch (shown above), and the supramedullary diverticula inside the neural canal. Based on pneumatic traces on the vertebrae we infer that the same diverticula were present in sauropods, as shown up above in the Diplodocus figures from Schwarz et al. (2007), and those left-and-right communications probably allowed the infection to develop more or less symmetrically. Or to put it another way, the symmetrical infections are additional evidence that the diverticula on the left and right sides of the neck were connected across the midline, and birds show that there are several ways that could have happened.

CT scans of cervical 7 of MOR 7029. Photograph and scan model of the vertebra ((A,B) respectively). The colored lines in (B) correspond to the scan slices (and scan interpretative drawings below). White arrows point to the external feature, while black arrows denote the hyperintense bone and irregular voids. (C) Comparison of the abnormal tissue composition of MOR 7029 (left), compared to that of a ‘normal’ diplodocine (right). Text and white arrows indicate the various features different shared/differentiated between the two. For the interpretative drawings, white = ‘normal’ bone, grey = hyperintense bone, black = irregular voids. Woodruff et al. (2022: fig. 2).

Another possibility is that a good chunk of the internal structure Dolly’s vertebrae was infected, and the lesions that we see on the surface are just the groady tips of big, disgusting icebergs of infected bone. In fact, that’s pretty much what the CT scans show. So possibly the infection started on one side of each vertebra and basically burrowed through to reach the other side. That would probably take weeks or months, whereas the infection could have spread across the midline through diverticula in hours or days, so I think the latter scenario is still the most plausible explanation for the presence of the lesions on both sides of the affected vertebrae.

In summary, I don’t think Dolly tells us anything surprising that we didn’t suspect before. Rather, the pattern of infection in Dolly makes perfect sense if the diverticula of sauropods were essentially bird-like, and that pattern is difficult to explain any other way.

Finding skeletal traces of a respiratory infection in Dolly was still a crazy lucky break, and that’s something I’ll discuss more in the next post in this series.

References

Turkey skeleton audit

February 16, 2022

Back in at least 2008 — maybe earlier — I kept all the bones from our good-sized Christmas turkey. Of course, it’s missing the head, neck and feet, but otherwise it’s pretty much all there. (I may also have the neck, but if so then it was supplied as a separate item, and prepared separately.) Here is the box of postcervical bones:

Postcervical skeleton of a mature domestic turkey Meleagris gallopavo domesticus, complete except for feet.

As I was transferring them to a better box today, it occurred to me to lay them  out and see how much sense I could make of them. Here’s what I did with the bones I was happy about:

Postcervical skeleton of a mature domestic turkey Meleagris gallopavo domesticus, complete except for feet. Some small bones omitted (see below). Laid out roughly as in life, in dorsal view.

I should  have put something in the photo to act as a scale-bar, because it’s not apparent from this photo that a turkey is a pretty big thing. From top to bottom of the skeleton as I laid it out here is about 90 cm.

Here are my (in some cases tentative) identifications of the bones:

Postcervical skeleton of a mature domestic turkey Meleagris gallopavo domesticus, complete except for feet. Some small bones omitted (see below). Laid out roughly as in life, in dorsal view. Bones are tentatively labelled. DO NOT USE FOR TUTORIAL PURPOSES.

Are there any obvious mistakes in there? And have I got any of the bones left-right reversed?

Now, here are all the other bones that I was less confident about the positions of:

Postcervical skeleton of a mature domestic turkey Meleagris gallopavo domesticus, complete except for feet. Small bones only.

On the left of course we have the dorsal ribs, but I’ve not been able to arrange them all into near pairs, nor figure out what order I should impose on the pairs that I do have. I’m not even sure how many pairs I should have. On the right are other paired bones whose identity I can’t figure out. I am guessing that the longer ones are probably sternal ribs and that the irregularly shaped ones might be parts of the wrist, but I would welcome corrections and clarifications. Finally, the middle column contains the bones whose idea I have little or no idea about, and which don’t appear to be paired. Any ideas?


By the way, I found this image useful in figuring out the identities of the appendicular bones:

Skeletal reconstruction of a domestic turkey, published in 1808. Source unknown (leave a comment if you can identify it).

And this one useful for the bones of the wing and especially the hand:

Human and bird arm skeletons compared. Source unknown.

More from this skeleton another time!

Okay, this is cool: with the help of Ryan Ridgely, my coauthor* Larry Witmer used the CT scans of the two best infected vertebrae of Dolly to create 3D models, which are now viewable on Sketchfab. (See the announcement post about Dolly here, and our open-access paper on her pathological vertebrae here.)

*Yes, it is super-awesome to have Larry as a coauthor, after almost a quarter-century of admiring his work and standing on his shoulders.

The lesions are pretty subtle, and I intend to update this post with screenshots of the models with the infected bone highlighted, but I didn’t want to hold up getting the models out. UPDATE a couple of hours later: Cary kindly gave me a hand figuring out which bits of the vertebrae are infected. It’s not super-obvious at the resolution of these models, and not all of the infected bone is bubbling outward like cauliflower. More information is coming! Also, I tagged the vertebrae with their serial positions. C7 is in front of C6 because that’s how they went through the CT scanner. 

We’ve deliberately been a bit vague about what, exactly, Dolly is, beyond a diplodocid from the Morrison Formation of Montana. The answer is that Cary Woodruff is leading a team on a very well-illustrated monographic description of Dolly, which will be along in due time. So expect even more goodies in the future. Follow Cary on Twitter (@DoubleBeam, a reference to Diplodocus) for updates on all kinds of interesting stuff.

In the meantime, go have fun with the new toys!

Reference

 

I was at the SVP meeting in Albuquerque in 2018 when Cary Woodruff called me over and said he had something cool to show me. “Something cool” turned out to be photos of infected sauropod vertebrae from the Morrison Formation of Montana. Specifically, some gross, cauliflower-looking bony lesions bubbling up in the air spaces on the sides of the vertebrae.

Pathologic pneumatic tissue in MOR 7029. (A) Schematic map of the neck of Diplodocus (Hatcher 1901; bones not present in grey), with the pathologic structures denoted in red. (B) Cervical 5 of MOR 7029 with red box highlighting the pathologic structure; close up in (C) with interpretative drawing in (D) (by DCW) (pathology in red). Woodruff et al. (2022: fig. 1).

I was stoked, because I’ve been working on air-filled bones in sauropods since 1998, and in that time I’ve gotten countless versions of this question: “Do you ever see any evidence of respiratory infections in those air spaces?” For 20 years, the answer had been ‘no’, but now Cary was showing me a likely ‘yes’.

Better still, Cary asked me if I wanted to collaborate on writing up the case. He could have done it on his own, but right out of the gate he wanted to assemble a collaborative team. He also got paleopathologist and veterinarian Ewan Wolff, veterinary radiologist Sophie Dennison, and anatomist and paleontologist Larry Witmer. It was my first time collaborating with all of those folks, and it was really cool firing around ideas, observations, and references. Cary coined the clever title “Sauro-Throat” when we presented our preliminary results at SVP (Woodruff et al. 2020), and you’ll probably see it a lot in conjunction with this paper.

The elaborate and circuitous pulmonary complex of the sauropod, with the hypothetical route of infectious pathway in MOR 7029. Skeletal reconstruction of the diplodocine Galeamopus pabsti by and copyright of Francisco Bruñén Alfaro to scale with MOR 7029. Human scale bar is the exemplar of pandemic education and rationalism, Dr. Anthony Fauci, at his natural height of 170 cm. Woodruff et al. (2022: fig. 3).

A little over three years after our meet-up in Albuquerque, one global pandemic notwithstanding, our results are out this morning in Scientific Reports (Woodruff et al. 2022). Normally I’d write a mini-dissertation about our findings, but I decided to do a little video explainer instead. That’s the video linked up top — many thanks to Fiona Taylor (music), Brian Engh (paleoart), and Jennifer Adams (filming and editing) for the timely help in getting it done.

I’ll have more to say about this in the future. For now, the paper is a free download at this link. Go have fun!

UPDATE later the same day:

Woo-hoo! Dolly is the top science story on Google News:

Google News UK:

The Guardian — with fabulous quotes by Steve Brusatte and, especially, Mike Benton:

…and probably others, but that’s enough navel-gazing for one afternoon.

References