Here’s one of my most prized possessions: a cannon bone from a giraffe. I got it last fall from Necromance, a cool natural history store in LA. Originally they had a matched pair on display in the front window. Jessie Atterholt got one of them last summer, and I got the other a few months later.

The cannon bones of hoofed mammals consist of fused metacarpals (in the forelimbs) or metatarsals (in the hindlimbs). In this case, the giraffe cannon bone in the top photo is the one from the right forelimb, consisting of the fused 3rd and 4th metacarpals, which correspond to the bones in the human hand leading to the middle and ring fingers. Only my third metacarpal is traced in the top photo. For maximum homology goodness I should have traced MC4, too, but I’m lazy.

I didn’t know that this was a right forelimb cannon bone when I got it. In fact, I only figured that out this afternoon, thanks to the figures and text descriptions in Rios et al. (2016), which I got free through Palaeontologia Electronica (you can too). The weirdly large and perfectly circular holes at the ends of my cannon bone were clearly drilled out by somone, I guess maybe for mounting purposes? At first I thought it might have been to help the marrow cook out of the shaft of the bone during simmering and degreasing, but none of the drilled holes intersect the main marrow cavity, they’re just in the sponge of trabecular bone at the ends of the element.

This post is a sequel to one from last year, “Brachiosaurus and human metacarpals compared“, which featured metacarpal 3 from BYU 4744, the partial skeleton of Brachiosaurus from Potter Creek, Colorado. I know what everyone’s thinking: can we make these two high-browsing giants throw hands?

Yes, yes we can. The giraffe cannon bone is 75.5cm long, and the brachiosaur metacarpal is 57cm long, or 75.5% the length of the giraffe element. I scaled the two bones correctly in the above image. My hands aren’t the same size because they’re at different distances from the camera, illustrating the age-old dictum that scale bars are not to be trusted.

The Potter Creek brachiosaur is one of the largest in the world–here’s me with a cast of its humerus–but ‘my’ giraffe is not. World-record giraffes are about 19 feet tall (5.8m), and doing some quick-and-dirty cross-scaling using the skeleton photo above suggests that the metacarpal cannon bone in a world-record giraffe should be pushing 90cm. So the giraffe my cannon bone is from was probably between 15.5 and 16 feet tall (4.7-4.9m), which is still nothing to sniff at.

I don’t know how this bone came to be at Necromance. I assume from an estate sale or something. I only visited for the first time last year, and at that time they had three real bones from giraffes out in the showroom: the two cannon bones and a cervical vertebra. They might have put out more stuff since–it’s been about six months since I’ve been there–but all of the giraffe bones they had at that point have been snapped up by WesternU anatomists. Jessie and I got the cannon bones, and Thierra Nalley got the cervical vertebra, which is fair since she works on the evolution of necks (mostly in primates–see her Google Scholar page here). I don’t know if there are any photos of Thierra’s cervical online, but Jessie did an Instagram post on her cannon bone, which is nearly as long as her whole damn leg.

There will be more anatomy coming along soon, and probably some noodling about sauropods. Stay tuned!

Reference

Ríos M, Danowitz M, Solounias N. 2016. First comprehensive morphological analysis on the metapodials of Giraffidae. Palaeontologia Electronica 19(3):1–39.

 

 

Credit: anonymous tattoo, Grant Harding for the caption.

Update. Here is the Instagram post that Grant got this from. Unfortunately it seems to be from an account that specialises in reposting others’ work without attribution, so we don’t know where the tattoo photo originated.

My eldest son Dan went out to visit his girlfriend Beth, shortly before the Coronavirus crisis began, during her university placement in Toulouse. While they were there, they bought me this gift:

As you can see, it’s a Lego-like self-assembly kit; but as you can also see from the mug in the background, it’s tiny. As  best I can make out, the blocks are half the length and width of Lego blocks, and about third the height. The whole model is about seven or eight inches (18-20 cm) from nose to tail.

Here’s a very quick walk-round, so you can appreciate the 3d shape.

I am properly impressed with this. It has the shape of the ribcage right, and the hips and shoulders, and the proportions are right so that it conveys with absolute conviction the quality of brachiosaurosity. It has a very posable neck that can be placed in a realistic life posture, and there are even hints of scapulae and ilia.

I made only one change from the instructions: I reoriented the forefoot so that we have a vertically oriented arcade of metacarpals rather than a plantigrade forefoot.

It was a very picky build. The instructions recommend using Nanoblock tweezers, sold separately, but I just used my big clumsy fingers, so that ribs and legs and things were constantly falling off. The process was rather like what this video shows, but much slower.

If you want one of your own, you can get it from Amazon UK or from Amazon US. I recommend it for serious sauropod lovers, but would be infuriating for children, and requires patience and precision to assemble.

Oh, and kit came with plenty of spare parts, in case you lose some of them: enough that Dan was able to make a juvenile with the leftovers.

 

I’ve written four posts about the R2R debate on the proposition “the venue of its publication tells us nothing useful about the quality of a paper”:

A debate of this kind is partly intended to persuade and inform, but is primarily entertainment — and so it’s necessary to stick to the position you’ve been assigned. But I don’t mind admitting, once the votes have been counted, that the statement goes a bit further than I would go in real life.

It took me a while to figure out exactly what I did think about the proposition, and the process of the debate was helpful in getting me the point where I felt able to articulate it clearly. Here is where I landed shortly after the debate:

The venue of its publication can tell us something useful about a paper’s quality; but the quality of publication venues is not correlated with their prestige (or Impact Factor).

I’m fairly happy with this formulation: and in fact, on revisiting my speech in support of the original proposition, it’s apparent that I was really speaking in support of this modified version. I make no secret of the fact that I think some journals are objectively better than others; but that those with higher impact factors are often worse, not better.

What are the things that make a journal good? Here are a few:

  • Coherent narrative order, with methods preceding results.
  • All relevant information in one place, not split between a main document and a supplement.
  • Explicit methods.
  • Large, clear illustrations that can be downloaded at full resolution as prepared by the authors.
  • All data available, including specimen photos, 3D models, etc.
  • Open peer review: availability of the full history of submissions, reviews, editorial responses, rebuttal letters, etc.
  • Well designed experiment capable of replication.
  • Honesty (i.e. no fabicated or cherry-picked) data.
  • Sample sizes big enough to show real statistical effect.
  • Realistic assessment of the significance of the work.

And the more I look at such lists, the more I realise that that these quality indicators appear less often in “prestige” venues such as Science, Nature and Cell than they do in good, honest, working journals like PeerJ, Acta Palaeontologica Polonica or even our old friend the Journal of Vertebrate Paleontology. (Note: I am aware that the replication and statistical power criteria listed above generally don’t apply directly to vertebrate palaeontology papers.)

So where are we left?

I think — and I admit that I find this surprising — the upshot is this:

The venue of its publication can tell us something useful about a paper’s quality; but the quality of publication venues is inversely correlated with their prestige (or Impact Factor).

I honestly didn’t see that coming.

In the last post, I catalogued some of the reasons why Scientific Reports, in its cargo-cult attempts to ape print journals such as its stablemate Nature, is an objectively bad journal that removes value from the papers submitted to it: the unnatural shortening that relagates important material into supplementary information, the downplaying of methods, the tiny figures that ram unrelated illustrations into compound images, the pointless abbreviating of author names and journal titles.

This is particularly odd when you consider the prices of the obvious alternative megajournals:

So to have your paper published in Scientific Reports costs 10% more than in PLOS ONE, or 56% more than in PeerJ; and results in an objectively worse product that slices the paper up and dumps chunks of it in the back lot, compresses and combines the illustrations, and messes up the narrative.

So why would anyone choose to publish in it?

Well, the answer is depressingly obvious. As a colleague once expressed it to me “until I have a more stable job I’ll need the highest IFs I can pull off to secure a position somewhere“.

It’s as simple as that. PeerJ‘s impact factor at the time of writing is 2.353; PLOS ONE‘s is ‎2.776; That of Scientic Reports is ‎4.525. And so, it in the idiotic world we live in, it’s better for an author’s career to pay more for a worse version of his article in Scientific Reports than it is to pay less for a better version in PeerJ or PLOS ONE. Because it looks better to have got into Scientific Reports.

BUT WAIT A MINUTE. These three journals are all “megajournals”. They all have the exact same editorial criteria, which is that they accept any paper that is scientifically sound. They make no judgement about novelty, perceived importance or likely significance of the work. They are all completely up front about this. It’s how they work.

In other words, “getting into” Scientific Reports instead of PeerJ says absolutely nothing about the quality of your work, only that you paid a bigger APC.

Can we agree it’s insane that our system rewards researchers for paying a bigger APC to get a less scientifically useful version of their work?

Let me say in closing that I intend absolutely no criticism of Daniel Vidal or his co-authors for placing their Spinophorosaurus posture paper in Scientific Reports. He is playing the ball where it lies. We live, apparently, in a world where spending an extra $675 and accepting a scientifically worse result is good for your career. I can’t criticise Daniel for doing what it takes to get on in that world.

The situation is in every respect analogous to the following: before you attend a job interview, you are told by a respected senior colleague that your chances of getting the post are higher if you are wearing designer clothing. So you take $675 and buy a super-expensive shirt with a prominent label. If you get the job, you’ll consider it as bargain.

But you will never have much respect for the search committee that judged you on such idiotic criteria.

As I was figuring out what I thought about the new paper on sauropod posture (Vidal et al. 2020) I found the paper uncommonly difficult to parse. And I quickly came to realise that this was not due to any failure on the authors’ part, but on the journal it was published in: Nature’s Scientific Reports.

A catalogue of pointless whining

A big part of the problem is that the journal inexplicably insists on moving important parts of the manuscript out of the main paper and into supplementary information. So for example, as I read the paper, I didn’t really know what Vidal et al. meant by describing a sacrum as wedged: did it mean non-parallel anterior and posterior articular surfaces, or just that those surfaces are not at right angles to the long axis of the sacrum? It turns out to be the former, but I only found that out by reading the supplementary information:

The term describes marked trapezoidal shape in the
centrum of a platycoelous vertebrae in lateral view or in the rims of a condyle-cotyle (procoelous or opisthocoelous) centrum type.

This crucial information is nowhere in the paper itself: you could read the whole thing and not understand what the core point of the paper is due to not understanding the key piece of terminology.

And the relegation of important material to second-class, unformatted, maybe un-reviewed supplementary information doesn’t end there, by a long way. The SI includes crucial information, and a lot of it:

  • A terminology section of which “wedged vertebrae” is just one of ten sub-sections, including a crucial discussion of different interpretation of what ONP means.
  • All the information about the actual specimens the work is based on.
  • All the meat of the methods, including how the specimens were digitized, retro-deformed and digitally separated.
  • How the missing forelimbs, so important to the posture, were interpreted.
  • How the virtual skeleton was assembled.
  • How the range of motion of the neck was assessed.
  • Comparisons of the sacra of different sauropods.

And lots more. All this stuff is essential to properly understanding the work that was done and the conclusions that were reached.

And there’s more: as well as the supplementary information, which contains six supplementary figures and three supplementary tables, there is an additonal supplementary supplementary table, which could quite reasonably have gone into the supplementary information.

In a similar vein, even within the highly compressed actual paper, the Materials and Methods are hidden away at the back, after the Results, Discussion and Conclusion — as though they are something to be ashamed of; or, at best, an unwelcome necessity that can’t quite be omitted altogether, but need not be on display.

Then we have the disappointingly small illustrations: even the “full size” version of the crucial Figure 1 (which contains both the full skeleton and callout illustrations of key bones) is only 1000×871 pixels. (That’s why the illustration of the sacrum that I pulled out of the paper for the previous post, was so inadequate.)

Compare that with, for example, the 3750×3098 Figure 1 of my own recent Xenoposeidon paper in PeerJ (Taylor 2018) — that has more than thirteen times as much visual information. And the thing is, you can bet that Vidal et al. submitted their illustration in much higher resolution that 1000×871. The journal scaled it down to that size. In 2020. That’s just crazy.

And to make things even worse, unrelated images are shoved into multi-part illustrations. Consider the ridiculousness of figure 2:

Vidal et al. (2020: figure 2). The verticalization of sauropod feeding envelopes. (A) Increased neck range of motion in Spinophorosaurus in the dorso-ventral plane, with the first dorsal vertebra as the vertex and 0° marking the ground. Poses shown: (1) maximum dorsiflexion; (2) highest vertical reach of the head (7.16 m from the ground), with the neck 90° deflected; (3) alert pose sensu Taylor Wedel and Naish13; (4) osteological neutral pose sensu Stevens14; (5) lowest vertical reach of the head (0.72 m from the ground at 0°), with the head as close to the ground without flexing the appendicular elements; (6) maximum ventriflexion. Blue indicates the arc described between maximum and minimum head heights. Grey indicates the arc described between maximum dorsiflexion and ventriflexion. (B) Bivariant plot comparing femur/humerus proportion with sacrum angle. The proportion of humerus and femur are compared as a ratio of femur maximum length/humerus maximum length. Sacrum angle measures the angle the presacral vertebral series are deflected from the caudal series by sacrum geometry in osteologically neutral pose. Measurements and taxa on Table 1. Scale = 1000 mm.

It’s perfectly clear that parts A and B of this figure have nothing to do with each other. It would be far more sensible for them to appear as two separate figures — which would allow part B enough space to convey its point much more clearly. (And would save us from a disconcertingly inflated caption).

And there are other, less important irritants. Authors’ given names not divulged, only initials. I happen to know that D. Vidal is Daniel, and that J. L. Sanz is José Luis Sanz; but I have no idea what the P in P. Mocho, the A in A. Aberasturi or the F in F. Ortega stand for. Journal names in the bibliography are abbreviated, in confusing and sometimes ludicrous ways: is there really any point in abbreviating Palaeogeography Palaeoclimatology Palaeoecology to Palaeogeogr. Palaeoclimatol. Palaeoecol?

The common theme

All of these problems — the unnatural shortening that relagates important material into supplementary information, the downplaying of methods, the tiny figures that ram unrelated illustrations into compound images, even the abbreviating of author names and journal titles — have this in common: that they are aping how Science ‘n’ Nature appear in print.

They present a sort of cargo cult: a superstitious belief that extreme space pressures (such as print journals legitimately wrestle with) are somehow an indicator of quality. The assumption that copying the form of prestigious journals will mean that the content is equally revered.

And this is simply idiotic. Scientific Reports is an open-access web-only journal that has no print edition. It has no rational reason to compress space like a print journal does. In omitting the “aniel” from “Daniel Vidal” it is saving nothing. All it’s doing is landing itself with the limitations of print journals in exchange for nothing. Nothing at all.

Why does this matter?

This squeezing of a web-based journal into a print-sized pot matters because it’s apparent that a tremendous amount of brainwork has gone into Vidal et al.’s research; but much of that is obscured by the glam-chasing presentation of Scientific Reports. It reduces a Pinter play to a soap-opera episode. The work deserved better; and so do readers.

References

 

Daniel Vidal et al.’s new paper in Scientific Reports (Vidal et al. 2020) has been out for a couple of days now. Dealing as it does with sauropod neck posture, it’s obviously of interest to me, and to Matt. (See our earlier relevant papers Taylor et al. 2009, Taylor and Wedel 2013 and Taylor 2014.)

Overview

To brutally over-summarise Vidal et al.’s paper, it comes down to this: they digitized the beautifully preserved and nearly complete skeleton of Spinophorosaurus, and digitally articulated the scans of the bones to make a virtual skeletal mount. In doing this, they were careful to consider the neutral pose of consecutive vertebrae in isolation, looking at only one pair at a time, so as to avoid any unconscious biases as to how the articulated column “should” look.

Then they took the resulting pose, objectively arrived at — shown above in their figure 1 — and looked to see what it told them. And as you can well see, it showed a dramatically different pose from that of the original reconstruction.

Original skeletal reconstruction of Spinophorosaurus nigerensis (Remes et al. 2009:figure 5, reversed for ease of comparison). Dimensions are based on GCP-CV-4229/NMB-1699-R, elements that are not represented are shaded. Scale bar = 1 m.

In particular, they found that as the sacrum is distinctly “wedged” (i.e. its anteroposterior length is greater ventrally than it is dorsally, giving it a functionally trapezoidal shape, shown in their figure 1A), so that the column of the torso is inclined 20 degrees dorsally relative to that of the tail. They also found lesser but still significant wedging in the last two dorsal vertebrae (figure 1B) and apparently some slight wedging in the first dorsal (figure 1C) and last cervical (figure 1D).

The upshot of all this is that their new reconstruction of Spinophorosaurus has a strongly inclined dorsal column, and consequently an strongly inclined cervical column in neutral pose.

Vidal et al. also note that all eusauropods have wedged sacra to a greater or lesser extent, and conclude that to varying degrees all eusauropods had a more inclined torso and neck than we have been used to reconstructing them with.

Response

I have to be careful about this paper, because its results flatter my preconceptions. I have always been a raised-neck advocate, and there is a temptation to leap onto any paper that reaches the same conclusion and see it as corroboration of my position.

The first thing to say is that the core observation is absolutely right, — and it’s one of those things that once it’s pointed out it’s so obvious that you wonder why you never made anything of it yourself. Yes, it’s true that sauropod sacra are wedged. It’s often difficult to see in lateral view because the ilia are usually fused to the sacral ribs, but when you see them in three dimensions it’s obvious. Occasionally you find a sacrum without its ilium, and then the wedging can hardly be missed … yet somehow, we’ve all been missing its implications for a century and a half.

Sacrum of Diplodocus AMNH 516 in left lateral and (for our purposes irrelevant) ventral views. (Osborn 1904 figure 3)

Of course this means that, other thing being equal, the tail and torso will not be parallel with each other, but will project in such a way that the angle between them, measured dorsally, is less than 180 degrees. And to be fair, Greg Paul has long been illustrating diplodocids with an upward kink to the tail, and some other palaeoartists have picked up on this — notably Scott Hartman with his very uncomfortable-looking Mamenchisaurus.

But I do have three important caveats that mean I can’t just take the conclusions of the Vidal et al. paper at face value.

1. Intervertebral cartilage

I know that we have rather banged on about this (Taylor and Wedel 2013, Taylor 2014) but it remains true that bones alone can tell us almost nothing about how vertebrae articulated. Unless we incorporate intervertebral cartilage into our models, they can only mislead us. To their credit, Vidal et al. are aware of this — though you wouldn’t know it from the actual paper, whose single mention of cartilage is in respect of a hypothesised cartilaginous suprascapula. But buried away the supplementary information is this rather despairing paragraph:

Cartilaginous Neutral Pose (CNP): the term was coined by Taylor for “the pose found when intervertebral cartilage [that separates the centra of adjacent vertebrae] is included”. Since the amount of inter-vertebral space cannot be certainly known for most fossil vertebrate taxa, true CNP will likely remain unknown for most taxa or always based on estimates.

Now this is true, so far as it goes: it’s usually impossible to know how much cartilage there was, and what shape it took, as only very unusual preservational conditions give us this information. But I don’t think that lets us out from the duty of recognising how crucial that cartilage is. It’s not enough just to say “It’s too hard to measure” and assume it didn’t exist. We need to be saying “Here are the results if we assume zero-thickness cartilage, here’s what we get if we assume cartilage thickness equal to 5% centrum length, and here’s what we get if we assume 10%”.

I really don’t think it’s good enough in 2020 to say “We know there was some intervertebral cartilage, but since we don’t know exactly how much we’re going to assume there was none at all”.

The thing about incorporating cartilage into articulating models is that we would, quite possibly, get crazy results. I refer you to the disturbing figure 4 in my 2014 paper:

Figure 4. Effect of adding cartilage to the neutral pose of the neck of Diplodocus carnegii CM 84. Images of vertebra from Hatcher (1901:plate III). At the bottom, the vertebrae are composed in a horizontal posture. Superimposed, the same vertebrae are shown inclined by the additional extension angles indicated in Table 2.

I imagine that taking cartilage into account for the Spinophorosaurus reconstruction might have given rise to equally crazy “neutral” postures. I can see why Vidal et al. might have been reluctant to open that can of worms; but the thing is, it’s a can that really needs opening.

2. Sacrum orientation

As Vidal et al.’s figure 1A clearly shows, the sacrum of Spinophorosaurus is indeed wedge-shaped, with the anterior articular surface of the first sacral forming an angle of 20 degrees relative to the posterior articular surface of the last:

But I don’t see why it follows that “the coalesced sacrum is situated so that the posterior face of the last sacral centrum is sub-vertical. This makes the presacral series to slope dorsally and the tail to be subhorizontal (Figs. 1 and 4S)”. Vidal et al. justify this with the claim by saying:

Since a subhorizontal tail has been known to be present in the majority of known sauropods[27, 28, 29], the [osteologically induced curvature] of the tail of Spinophorosaurus is therefore compatible with this condition.

But those three numbered references are to Gilmore 1932, Coombs 1975 and Bakker 1968 — three venerable papers, all over fifty years old, dating from a period long before the current understanding of sauropod posture. What’s more, each of those three was about disproving the previously widespread assumption of tail-dragging in sauropods, but the wedged sacrum of Spinophorosaurus if anything suggests the opposite posture.

So my question is, given that the dorsal and caudal portions of the vertebral column are at some specific angle to each other, how do we decide which (if either) is horizontal, and which is inclined?

Three interpretations of the wedged sacrum of Spinophorosaurus, in right lateral view. In all three, the green line represents the trajectory of the dorsal column in the torso, and the red line that of the caudal column. At the top, the tail is horizontal (as favoured by Vidal et al. 2020) resulting in an inclined torso; at the bottom, the torso is horizontal, resulting in a dorsally inclined tail; in the middle, an intermediate posture shows both the torso and the tail slightly inclined.

I am not convinced that the evidence presented by Vidal et al. persuasively favours any of these possibilities over the others. (They restore the forequarters of Spinophorosaurus with a very vertical and ventrally positioned scapula in order to enable the forefeet to reach the ground; this may be correct or it may not, but it’s by no means certain — especially as the humeri are cross-scaled from a referred specimen and the radius, ulna and manus completely unknown.)

3. Distortion

Finally, we should mention the problem of distortion. This is not really a criticism of the paper, just a warning that sacra as preserved should not be taken as gospel. I have no statistics or even systematic observations to back up this assertion, but the impression I have, from having looked closely at quite a lot of sauropod vertebra, is the sacra are perhaps more prone to distortion than most vertebrae. So, for example, the very extreme almost 30-degree wedging that Vidal et al. observed in the sacrum of the Brachiosaurus altithorax holotype FMNH PR 25107 should perhaps not be taken at face value.

Now what?

Vidal el al. are obviously onto something. Sauropod sacra are screwy, and I’m glad they have drawn attention in a systematic way to something that had only been alluded to in passing previously, and often in a way that made it seems as though the wedging they describe was unique to a few special specimens. So it’s good that this paper is out there.

But we really do need to see it as only a beginning. Some of the things I want to see:

  • Taking cartilage into account. If this results in silly postures, we need to understand why that is the case, not just pretend the problem doesn’t exist.
  • Comparison of sauropod sacra with those of other animals — most important, extant animals whose actual posture we can observe. This might be able to tell us whether wedging really has the implications for posture that we’re assuming.
  • Better justification of the claim that the torso rather than the tail was inclined.
  • An emerging consensus on sauropod shoulder articulation, since this also bears on torso orientation. (I don’t really have a position on this, but I think Matt does.)
  • The digital Spinophorosaurus model used in this study. (The paper says “The digital fossils used to build the virtual skeleton are deposited and accessioned at the Museo Paleontológico de Elche” but there is no link, I can’t easily find them on the website and they really should be published alongside the paper.)

Anyway, this is a good beginning. Onward and upward!

References

  • Bakker, Robert T. 1968. The Superiority of Dinosaurs. Discovery 3:11–22.
  • Coombs, Walter P. 1975. Sauropod habits and habitats. Palaeogeography, Palaeoclimatology, Palaeoecology 17:1-33.
  • Gilmore, Charles W. 1932. On a newly mounted skeleton of Diplodocus in the United States National Museum. Proceedings of the United States National Museum 81:1-21.
  • Hatcher, John Bell. 1901. Diplodocus (Marsh): its osteology, taxonomy, and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63.
  • Osborn, Henry F. 1904. Manus, sacrum and caudals of Sauropoda. Bulletin of the American Museum of Natural History 20:181-190.
  • Taylor, Michael P. 2014. Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs. PeerJ 2:e712. doi:10.7717/peerj.712
  • Taylor, Michael P., and Mathew J. Wedel. 2013c. The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs. PLOS ONE 8(10):e78214. 17 pages. doi:10.1371/journal.pone.0078214
  • Taylor, Michael P., Mathew J. Wedel and Darren Naish. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54(2):213-230.
  • Vidal, Daniel, P Mocho, A. Aberasturi, J. L. Sanz and F. Ortega. 2020. High browsing skeletal adaptations in Spinophorosaurus reveal an evolutionary innovation in sauropod dinosaurs. Scientific Reports 10(6638). Indispensible supplementary information at https://static-content.springer.com/esm/art%3A10.1038%2Fs41598-020-63439-0/MediaObjects/41598_2020_63439_MOESM1_ESM.pdf
    doi:10.1038/s41598-020-63439-0