DIY dinosaurs: building a life-size Brachiosaurus humerus standee
January 23, 2023
Building life-size standees of big dinosaur bones has been a gleam in my eye for a long time. What finally pushed me over the edge was an invitation from Oakmont Outdoor School here in Claremont, California, to come talk about dinosaurs. It was an outdoor assembly, with something like 280 kids in attendance, and most of my show and tell materials are hand-sized and would not show up well from a distance. Plus, I wanted to blow people away with the actual size of big dinosaur bones.
I started with a life-size poster print of FHPR 17108, the complete right humerus of Brachiosaurus from Brachiosaur Gulch in Utah (the story of the discovery and excavation of that specimen is here). I used the image shown above, scaled to print at 7 feet by 3 feet. You can see that print lying on my living room floor in the previous post.
It was simpler and cheaper to get two 2 foot x 4 foot pieces of plywood than one big piece, so that’s what I did. I laid them out on the living room floor, cut out the poster print of the humerus from its background, traced the outline of the humerus onto the plywood, and then took the pieces outside to cut out the humerus shapes with a jigsaw.
The big piece of darker plywood is the brace that holds the two front pieces together. The smaller piece down at the distal end is a sort of foot, level with the bottom of the humerus but wider and flatter to give more stability. I used wood glue and a bunch of screws to hold everything together. Probably more screws than were strictly necessary, but I wanted to build this thing once and then never worry about it again, and screws and glue are cheap.
Even just the plywood outline without the print glued on looked pretty good. Early in the project I dithered on whether to make the thing out of plywood or foam core board. Foam core board would have been cheaper, easier to work with, and a lot lighter, but I also had doubts about its survivability. I want to use this thing for outreach for a long time to come.
To make the thing free-standing I added a kickstand in the back, made from a six-foot board and a hinge.
I used some screw-eyes and steel wire from a picture-hanging kit to add restraints to the kickstand, so it can’t open up all the way and collapse.
I didn’t want the kickstand flopping around during transit, and I also did not want the whole weight of the kickstand hanging cantilevered from the hinge when this thing is being carried horizontally, so I added a couple of blocks on either side for support, and some peel-and-stick velcro to hold the kickstand in place when it’s not being used.
I took the thing to Oakmont Outdoor School this morning and everybody loved it. I think the teachers were just as impressed as the kids. That’s Jenny Adams, the principal at Oakmont, who invited me to come speak.
This was a deeply satisfying project and it didn’t require any complex or difficult techniques. The biggest expense was the big poster print, and the most specialized piece of equipment was the jigsaw. You could save money by going black-and-white or just blowing up an outline drawing on a plotter, by scavenging the plywood instead of buying new (all my old plywood has been turned into stuff already), or by using foam core board or some other lightweight material.
Many thanks to Jenny Adams and the whole Oakmont community for giving me a chance to come speak, and for asking so many excellent questions. However much fun it was for you all, I’m pretty sure it was even more fun for me. And now I have an inconveniently gigantic Brachiosaurus humerus to worship play with!
I am about a great work
January 21, 2023
I’m also teaching in two anatomy courses and in the process of moving residences (hence bins and boxes and whatnot), so the timing’s…not great. But needs must when the devil drives.
Further bulletins as events warrant.
Obscure vertebral anatomy term of the day: bouton
October 25, 2022
Long-time readers will recall that I’m fascinated by neurocentral joints, and not merely that they exist (although they are pretty cool), but that in some vertebrae they migrate dorsally or ventrally from their typical position (see this and this).
A few years ago I learned that there is a term for the expanded bit of neural arch pedicle that contributes to the centrum in vertebrae with ventrally-migrated neurocentral joints: the bouton, which is French for ‘button’. Here’s an example in the unfused C7 of a subadult sheep. Somebody gifted me a handful of these things a few years ago, and I’ve been meaning to blog about them forever. Many thanks, mysterious benefactor. (I mean, only mysterious to me, because my memory is crap; I’m sure you know who you are, and if you ever read this, feel free to remind me. And thanks for the dead animal parts!)
Guess what? You have these things, too! Or at least you did; if you’re old enough to be reading this, your boutons fused with the rest of the separate bits of your vertebrae a long time ago, between the ages of 2 and 5 (according to Bagnall et al. 1977). Here’s a diagram from Schaefer et al. (2009: p.99) showing the separate centrum and neural arch elements in a thoracic vertebra of a human toddler. So, hey, cool, we all had boutons, just like sheep. And just like some sauropods. (You didn’t think I was going to do a whole OVATOD post without sauropods, did you?)
Here’s our old friend BIBE 45885, an unfused caudal neural arch (or perhaps neural ring) of Alamosaurus, which I’ve been freaking out over for five years now. Those fat bits of neural arch that very nearly close off the neural canal ventrally? Boutons, baby! Big, beautiful boutons. In this photo it looks like the paired boutons meet on the midline, but in fact they merely overlap from this point of view — there is a narrow (<1mm) squiggly gap between them. Given how narrow that gap is, I suspect the two boutons probably would have fused to each other before either of them fused to the centrum, if this particular animal hadn’t died first.
Here’s an unfused dorsal centrum of Giraffatitan, MB.R. 3823, which I yapped about in this post. This vertebra is the spiritual opposite of the Alamosaurus caudal shown above: instead of the neural canal being nearly enclosed by bits of the neural arch wrapping around ventrally, the neural canal is nearly enclosed dorsally by bits of the centrum sticking up on either side and wrapping around dorsally. As with the boutons of the Alamosaurus caudal, the two expanded bits of centrum stuff in this Giraffatitan dorsal approach each other very closely but don’t quite meet; you can fit a piece of paper between them, but not a heck of a lot more. In essence, those “two expanded bits of centrum stuff” are centrum boutons that project up into what I suppose we’ll keep calling a ‘neural arch’ even though it’s neither very neural nor an arch. Or perhaps anti-boutons? With apologies to Gould and Vrba (1982), here we have another missing term in the science of form.
Why do we, and sheep, and prolly lots of other mammals, and some sauropods, have boutons? Presumably to strengthen the neurocentral joints by expanding the joint surface area. I don’t know if anyone has ever tested that — if you do, please let me know in the comments.
Many thanks to Thierra Nalley, who may be the only person I know besides Mike who spends more time thinking about vertebrae than I do, for introducing me to the term ’bouton’ a few years ago. If for some reason you want to corrupt your sensibilities reading about primate vertebrae, you could do a lot worse than checking out Thierra’s papers.
I don’t expect we’ll have a ton of OVATOD posts, in part because there aren’t a heck of a lot of vertebra parts that we haven’t already blogged about. But who knows, maybe Mike will write about prepostepipophyses or something. Stay tuned!
References
- Bagnall, K.M., Harris, P.F., and Jones, P.R.M. 1977. A radiographic study of the human fetal spine. 2. The sequence of development of ossification centers in the vertebral column. Journal of Anatomy 124(3): 791–802.
- Gould, S.J. and Vrba, E.S. 1982. Exaptation—a missing term in the science of form. Paleobiology 8(1): 4-15.
- Schaefer, M., Black, S., and Scheuer, L. 2009. Juvenile Osteology: A Laboratory and Field Manual. Academic Press, Burlington, MA, 369pp.
P.S. Can we all pitch in and make ’bouton’ the new ‘aglet‘? Please? Please?
Vertebrae of Haplocanthosaurus (A-C) and a giraffe (D-F) illustrating three ways of orienting a vertebra: articular surfaces vertical — or at least the caudal articular surface vertical (A and D), floor of the neural canal horizontal (B and E), and similarity in articulation (C and F). See the paper for details! Taylor and Wedel (2002: fig. 6).
This is a lovely cosmic alignment: right after the 15th anniversary of this blog, Mike and I have our 11th coauthored publication (not counting abstracts and preprints) out today.
This one started back in 2018, with Mike’s post, What does it mean for a vertebra to be “horizontal”? That post and subsequent posts on the same topic (one, two, three) provoked interesting discussions in the comment threads, and convinced us that there was something here worth grappling with. We gave a presentation on the topic at the 1st Palaeontological Virtual Congress that December, which we made available as a preprint, which led to us writing the paper in the open, which led to another preprint (of the paper this time, not the talk).
Orienting vertebrae with the long axis of the centrum held horizontally seems simple enough, but choosing landmarks can be surprisingly complex. Taylor and Wedel (2022 fig. 5).
This project represented some interesting watersheds for us. It was not our first time turning a series of blog posts into a paper — see our 2013 paper on neural spine bifurcation for that — but it was our first time writing a joint paper in the open (Mike had started writing the Archbishop description in the open a few months earlier). It was also the last, or at least the most recent, manuscript that we released as a preprint, although we’ve released some conference presentations as preprints since then. I’m much less interested in preprints than I used to be, for reasons explained in this post, and I think Mike sees them as rather pointless if you’re writing the paper in the open anyway, which is his standard approach these days (Mike, feel free to correct me here or in the comments if I’m mischaracterizing your position).
So, we got it submitted, we got reviews, and then…we sat on them for a while. We have both struggled in the last few years with Getting Things Done, or at least Getting Things Finished (Mike’s account, my own), and this paper suffered from that. Part of the problem is that Mike and have far too many projects going at any one time. At last count, we have about 20 joint projects in various stages of gestation, and about 11 more that we’ve admitted we’re never going to get to (our To Don’t list), and that doesn’t count our collaborations with others (like the dozen or so papers I have planned with Jessie Atterholt). We simply can’t keep so many plates spinning, and we’re both working hard at pruning our project list and saying ‘no’ to new things — or, if we do think of new projects, we try to hand them off to others as quickly and cleanly as possible.
Two different ways of looking at a Haplocanthosaurus tail vertebra. Read on for a couple of recent real-life examples. Taylor and Wedel (2022: fig. 2).
Anyway, Mike got rolling on the revisions a few months ago, and it was accepted for publication sometime in late spring or early summer, I think. Normally it would have been published in days, but the Journal of Paleontological Techniques was moving between websites and servers, and that took a while. But Mike and I were in no tearing rush, and the paper is out today, so all is well.
One of the bits of the paper that I’m most proud of is the description of cheap and easy methods for determining the orientation of the neural canal. For neural canals that are open, either because they were fully prepped or never full of matrix to begin with, there’s the rolled-up-piece-of-paper method, which I believe first appeared on the blog back when I was posting photos of the tail vertebrae of the Brachiosaurus altithorax holotype. For neural canals that aren’t open, Mike came up with the Blu-tack-and-toothpick method, as shown in Figure 12 in the new paper:
A 3d print of NHMUK PV R2095, the holotype of Xenoposeidon, illustrating the toothpick method of determining neural canal orientation. Taylor and Wedel (2022: fig. 12).
I know both methods work because I recently had occasion to use them, studying the Haplocanthosaurus holotypes (see this post). For CM 572, the neural canal of the first caudal vertebra is full of matrix, so I used a variant of the toothpick method. I didn’t actually have Blu-tack or toothpicks, so I cut thin pieces of plastic from the edge of an SVP scale bar and stuck them in bits of kneadable eraser. It worked just fine:
The neural canal of caudal 2 was prepped, so I could use the rolled-up-piece-of-paper method:
(Incidentally, Mike and I refer to our low-tech orientation-visualizers as “neural-canal-inators”, in honor of Dr. Heinz Doofenshmirtz from Phineas and Ferb.)
In the above photos, notice how terribly thin the base of the neural arch is, antero-posteriorly. Both of these vertebrae are in pretty good shape, without much breakage or missing material, and their morphology is broadly consistent with that of other proximal caudals of Haplocanthosaurus, so we can’t write this off as distortion. As weird as it looks, this is just what Haplo proximal caudals were like. And with the neural canals held horizontally, the first two caudals end up oriented like so:
Now, as we pointed out in the paper, the titular question is not about determining the posture of the vertebrae in life, it’s about defining the directions ‘cranial’ and ‘caudal’ for isolated vertebrae — Mike asked the question back when for the holotype (single) dorsal vertebra of Xenoposeidon. But an interesting spin-off for me has been getting confronted with the weirdness of vertebrae whose articular surfaces are nowhere near orthogonal with their neural canals. I tilted those CM 572 Haplo caudals so that their neural canals were horizontal partly because that’s the preferred orientation that Mike and I landed on in the course of this work, but also partly because to me, that’s a more arresting image than the preceding ones with the articular faces held vertically. I’m both freaked out and fascinated, and that seems like a promising combination — there are mysteries here that cry out to be solved.
As usual, we have loads of people to thank. In addition to all those listed in the Acknowledgments of the new paper, I’m grateful to Matt Lamanna and Amy Henrici of the Carnegie Museum of Natural History for letting me play with study the Haplo specimens in their care. Mike and I also owe a huge thanks to the editorial team at the Journal of Paleontological Techniques. We reached out to them a few days ago to ask if it might be possible to get our in-press paper done and out in time for SV-POW!’s anniversary weekend, and they pitched in to make it happen.
What’s next? We weighed the evidence and formulated what the best solution we could think of. Now it’s up to the world to decide if that was a useful contribution. The comment thread is open — let’s find out.
Happy 15th birthday to SV-POW!
October 1, 2022
Matt and I, with our silent partner Darren, started SV-POW! fifteen years ago to the day, as a sort of jokey riff on NASA’s Astronomy Picture of the Day. Our first post, on 1 October 2007, was a photograph of what we called “the most iconic of sauropod vertebrae, the 8th cervical of the Brachiosaurus brancai type specimen HMN SII”. Now, here in glorious monochrome, is that same vertebra fifteen years on!
(The specimen that it’s from is now recognised as belonging to the separate brachiosaurid genus Giraffatitan, and it’s the paralectotype of the species Giraffatitan brancai.)
Obviously what we’re seeing here is not the real thing — very heavy and very fragile — but a life-sized 3D model, carved out of styrofoam by a CNC machine (computerized carving machine) using surface-scan data of the original specimen. This was done at Research Casting International, and we bring you this photo courtesy of Peter May, Garth Dallman, and the rest of the folks at RCI.
The inside of RCI’s workshop is an interesting place — I’ve never been there myself, but it’s at least Matt’s second visit, and it’s very high on my To Visit list. I especially like the “RAPTOR” box just behind and above Matt’s head.
This photo, unfortunately, makes the vertebra look smaller than it is, because when Matt took the selfie he was holding it further back than his own head. It’s still interesting, though, to see where the balance point is for holding it one-handed. It seems that the rear half of the vertebra is denser than the front half. But of course, that’s only when it’s a solid constant-density volume. The real bone, with all its pneumatic internal structures, might have been quite different.
Needless to say, HMN SII:C8 (or MB.R.2181:C8, as we must now call it) is a very old friend on this blog, to the point where it should probably have a category of its own. Among many other appearances it’s popped up in tutorials 2 (Basic vertebral anatomy), 4 (Laminae) and 21 (How to measure the length of a centrum), as well as Bifid Brachiosaurs, Batman! (6 September 2009), What a 23% longer torso looks like (20 September 2009), Plateosaurus is pathetic and its doppelganger Plateosaurus is comical (16 January and 5 September 2013), and of course Copyright: promoting the Progress of Science and useful Arts by preventing access to 105-year-old quarry maps (11 October 2015).
If you want to see more exciting photos of this glorious vertebra — and indeed of many other sauropod vertebrae — stay tuned for the next fifteen years!
“Scaled beasts” Giraffatitan skull
November 22, 2021
Back in June, I saw a series of tweets by sculptor and digital artist Ruadhrí Brennan, showing off the work he’d been doing on sculpting brachiosaurid skulls: Giraffatitan, Brachiosaurus (based on the Felch Quarry skull USNM 5730) and Europasaurus. Impressed, I asked if he would send a Giraffatitan skull, and here it is!
You can immediately see two things: one, it’s good. (I’ll have more to say about this.) And second, it’s small, It’s leaned up against a stack of smallish coins in this photo, to give me the true lateral perspective I wanted, and those coins (10p, 20p, 20p, 5p) also make a decent ad-hoc scalebar.
In fact, it’s sculpted at 1:10 scale — about 9 cm from the tip of the premaxilla to the rearmost projection of the parietals, implying about 90 cm total length for the skull MB.R.2223.1 (“t 1”) — a figure surprisingly difficult to find in the literature (can anyone help?) but consonant with how big it seems in real life.
At that scale, the detail is pretty amazing. Its not just that the overall proportions of the skull are so true, but the visible junctions between the bones — as for example between the paired ascending processes of the two premaxilae, as apparent in anterior view — but the texture of the bone, including things like vascular foramina for the lips but also just straight-up bone surface. It’s a lovely job.
This view is a pretty good match for what we used in the second Shedloads of Awesome post back in 2008 — in fact, let’s just put them side by side so we can compare more easily.
As you can see, I slightly muffed the photography of the model — I could do a better job of matching the aspect I tried. But we’re in the ballpark, and it’s easy to see from this angle how much the model skull really couldn’t be anything other than what it is. That said, there are a few places where it seems the bone junctions don’t quite match those of the real skull. Most obviously, in the real skull the lacrimal seems to laterally overlap the nasal dorsally and the maxilla/jugal ventrally, whereas in the model it fits in more neatly with both. But I am inclined to think this is not so much a mistake as a correction to allow for poor articulation and distortion in the original — a restoration, in other words.
Here’s a different oblique view:
The story here really is just what an odd shape this familiar skull is when viewed in this perspective, and a valuable reminder that we should all try to avoid getting too suckered in by the over-familiar lateral views of various things. 3D objects are weird. They trick you. That’s why, for example, two scapulae that look very different in photos might actually be very similar in reality: the difference is in the angle of the photograph, not in the photographed bones.
Anyway, moving on from that cautionary tale …
The key takeaway is really just that this Giraffatitan skull is very nice, and it leaves me wishing I also had the Camarsaurus one for comparison … even though camarsaurs are ugly and stupid.
Oh, what’s that you say? You want a Giraffatitan skull of your very own? Well, you can have one: get it from the Scaled Beasts shop!
My Brachiosaurus talk for Dinosaur Journey is now on YouTube
October 20, 2021
My Oct. 13 National Fossil Day public lecture, “Lost Giants of the Jurassic”, for the Museums of Western Colorado – Dinosaur Journey is now up on their YouTube channel. First 48 minutes are talk, last 36 minutes are Q&A with audience, moderated by Dr. Julia McHugh. New stuff from the 2021 field season — about which I’ll have more to say in the future — starts at about the 37-minute mark. Hit the 44-minute mark (and this and this) to find out what to do with all of the unwanted bird necks that will be floating around at the upcoming holidays.
Finally, big thanks to Brian Engh for finding our brachiosaur and for letting me use so much of his art, to John Foster, Kaelen Kay, Tom Howells, Jessie Atterholt, Thierra Nalley, and Colton Snyder for such a fun field season this year, and to Julia McHugh for giving me the opportunity to yap about one of my favorite dinosaurs!
Matt Wedel will be yapping about Brachiosaurus. Again.
October 7, 2021
I have the honor of giving the National Fossil Day Virtual Lecture for The Museums of Western Colorado – Dinosaur Journey, next Wednesday, October 13, from 7:00 to 8:00 PM, Mountain Daylight Time. The title of my talk is “Lost Giants of the Jurassic” but it’s mostly going to be about Brachiosaurus. And since I have a whole hour to fill, I’m gonna kitchen-sink this sucker and put in all the good stuff, even more than last time. The talk is virtual (via Zoom) and free, and you can register at this link.
The photo up top is from this July. That’s John Foster (standing) and me (crouching) with the complete right humerus of Brachiosaurus that we got out of the ground in 2019; that story is here. The humerus is in the prep lab at the Utah Field House of Natural History State Park Museum in Vernal, and if you go there, you can peer through the tall glass windows between the museum’s central atrium and the prep lab and see it for yourself.
If you’ve forgotten what a humerus like that looks like in context, here’s the mounted Brachiosaurus skeleton at the North American Museum of Ancient Life with my research student, Kaelen Kay, for scale. Kaelen is 5’8″ (173cm) and as you can see, she can just get her hand on the animal’s elbow. The humerus–in this case, a cast of the right humerus from the Brachiosaurus altithorax holotype–is the next bone up the line. Kaelen came out with us this summer and helped dig up some more of our brachiosaur–more on that story in the near future.
Want more Brachiosaurus? Tune in next week. Here’s that registration link again. I hope to see you there!
How big was the Archbishop?
June 2, 2021
Various Internet rumours have suggested that the Archbishop is a super-giant sauropod one third larger than the mounted Giraffatitan specimen MB.R.2181 (formerly HMN SII). This is incorrect.
Migeod’s assessment of the size of the animal was based on the vertebrae: “The [neck] vertebrae found give a 20-foot [6.10 m] length […] The length of the back including the sacral region was about 15 feet [4.57 m]. The eight or nine caudal vertebrae cover about 6 feet [1.83 m]” (Migeod 1931a:90). This gives the total preserved length of the skeleton as 41 feet (12.50 m). By comparison, Janensch (1950b:102) gives lengths of portions of the mounted skeleton of MB.R.2181 as 8.78m (neck), 3.92m (torso) and 1.07m (sacrum) for a torso-plus-sacrum length of 4.99m. On this basis, the preserved neck of NHMUK PV R5937 is only 69% as long as that of MB.R.2181, but since the first four vertebrae were missing and omitted from Migeod’s measurement, this factor cannot be taken at face value. More informative is the torso-plus-sacrum length, which in NHMUK PV R5937 is 92% the length of MB.R.2181.
This is consonant with measurements of individual elements, which compare as follows:
Table 4. Comparative measurements of Archbishop and Giraffatitan elements
| Element | Measurement (cm) | Archbishop | Giraffatitan | Ratio |
|---|---|---|---|---|
| Torso plus sacrum | total length | 457 | 499 | 0.916 |
| C10 (mC4) | centrum length | 99 | 100 | 0.990 |
| C11 (mC3) | centrum length | 104 | 100[1] | 1.040 |
| D4 (mD3) | centrum length | 27 | 36 | 0.750 |
| Longest rib | length over curve | 235 | 263 | 0.894 |
| Left scapulocoracoid | length over curve | 221 | 238[2] | 0.929 |
| Right humerus | length | 146 | 213 | 0.685 |
| Right humerus | width | 51 | 59 | 0.864 |
| Right ilium | length | 98 | 123[3] | 0.797 |
| Right ilium | height | 79 | 96[4] | 0.823 |
| Femur | length | 122 | 196[5] | 0.622 |
| Average | 0.846 |
Archbishop measurements taken from Migeod (1931a) and converted from imperial; Giraffatitan measurements are for MB.R.2181 except where noted, and are taken from Janensch (1950a:44) and Janensch (1961).
Notes.
[1] Janensch (1950a) did not report a total centrum length for C11, as its condyle had not been removed from the cotyle of C10; but since the length of its centrum omitting the condyle was, at 87 cm, identical to that of C10, it is reasonable to estimate its total length as also equal to that of C10.
[2] Janensch (1961:181) did not include measurements for the right scapula of MB.R.2181, which is incorporated into the mounted skeleton, but does give the proximodistal length of its right coracoid as 45 cm. Using the 193 cm length given for the similarly sized scapula Sa 9, we can deduce a reasonable total estimate of 238 cm for the scapulocoracoid.
[3] Estimated by Janensch (1950b:99) based on cross-scaling from the fibula and ilium of Find J from the Upper Saurian Marl.
[4] This is the measurement provided by Janensch (1961:199) for the ilium Ma 2, which is incorporated into the mounted skeleton, and which Janensch (1950b:99) considered to match MB.R.2181 very precisely.
[5] Based on a restoration of the midshaft which Janench (1950b:99) calcuated based on other finds.
Individual lines of this table should each be treated with caution: Migeod’s measurements may have been unreliable, and in any case are underspecified: for example, we do not know whether, when he gave a vertebra’s length, he included overhanging prezygapophyses or the condyle. Similarly, we know that Migeod (1931:96) wrote that a rib “was as much as 92.5 inches long”, but we do not know for certain that, like Janensch, he measured the length over the curve rather than the straight-line distance between the ends. And when Migeod says that the ilium “measured 38.5 by 31 inches” we do not know that the height was measured “at the public process”, as Janensch (1961:199) specified.
With those caveats in place, nevertheless, a picture emerges of a sauropod somewhat smaller than MB.R.2181, though by no means negligible. On average, the measurements come out about 15% smaller than those of Giraffatitan.
But this average conceals a great deal of variation. The cervical vertebrae are comparable in length to those of MB.R.2181 (The total of 203 cm for C10 and C11 in the Archbishop, only 1.5% longer than 200 cm for MB.R.2181, is a difference well within the margin of measurement error). The Archbishop’s scapulocoracoid may have been 93% as long as in MB.R.2181. But the limb bones are signficantly shorter (87% for the humerus and a scarcely credible 62% for the femur), and the humeri at least bseem to be have been proportionally more robust in the Archbishop: only 2.86 times as long as wide, whereas the ratio is 3.61 in MB.R.2181. If Migeod’s measurements can be trusted, we have here an animal whose neck is as long as that of Giraffatitan, but whose limbs are noticably shorter. These proportions corroborate the hypothesis that the Archbishop is not a specimen of Giraffatitan.
Amazing things are out there waiting to be noticed
March 22, 2021
It is said that, some time around 1590 AD, Galileo Galilei dropped two spheres of different masses from the Leaning Tower of Pisa[1], thereby demonstrating that they fell at the same rate. This was a big deal because it contradicted Aristotle’s theory of gravity, in which objects are supposed to fall at a speed proportional to their mass.
Aristotle lived from 384–322 BC, which means his observably incorrect theory had been scientific orthodoxy for more than 1,900 years before being overturned[2].
How did this happen? For nearly two millennia, every scientist had it in his power to hold a little stone in one hand and a rock in the other, drop them both, and see with his own eyes that they fell at the same speed. Aristotle’s theory was obviously wrong, yet that obviously wrong theory remained orthodox for eighty generations.
My take is that it happened because people — even scientists — have a strong tendency to trust respected predecessors, and not even to look to see whether their observations and theories are correct. I am guessing that in that 1,900 years, plenty of scientists did indeed do the stone-and-rock experiment, but discounted their own observations because they had too much respect for Aristotle.
But even truly great scientists can be wrong.
Now, here is the same story, told on a much much smaller scale.
Well into the 2010s, it was well known that in sauropods, caudal vertebrae past the first handful are pneumatized only in diplodocines and in saltasaurine titanosaurs. As a bright young sauropod researcher, for example, I knew this from the codings in important and respected phylogenetic analysis such as those of Wilson (2002) and Upchurch et al. (2004).
Until the day I visited the Museum für Naturkunde Berlin and actually, you know, looked at the big mounted Giraffatitan skeleton in the atrium. And this is what I saw:
That’s caudal vertebrae 24–26 in left lateral view, and you could not wish to see a nicer, clearer pneumatic feature than the double foramen in caudal 25.
That observation led directly to Matt’s and my 2013 paper on caudal pneumaticity in Giraffatitan and Apatosaurus (Wedel and Taylor 2013) and clued us into how much more common pneumatic hiatuses are then we’d realised. It also birthed the notion of “cryptic diverticula” — those whose traces are not directly recorded in the fossils, but whose presence can be inferred by traces on other vertebrae. And that led to our most recent paper on pneumatic variation in sauropods (Taylor and Wedel 2021) — from which you might recognise the photo above, since a cleaned-up version of it appears there as Figure 5.
The moral
Just because “everyone knows” something is true, it doesn’t necessarily mean that it actually is true. Verify. Use your own eyes. Even Aristotle can be wrong about gravity. Even Jeff Wilson and Paul Upchurch can be wrong about caudal pneumaticity in non-diplodocines. That shouldn’t in any way undermine the rightly excellent reputations they have built. But we sometimes need to look past reputations, however well earned, to see what’s right in front of us.
Go and look at fossils. Does what you see contradict what “everyone knows”? Good! You’ve discovered something!
References
- Taylor, Michael P., and Mathew J. Wedel. 2021. Why is vertebral pneumaticity in sauropod dinosaurs so variable? (version 5) Qeios 1G6J3Q.5. doi:10.32388/1G6J3Q.5
- Upchurch, Paul, Paul M. Barrett and Peter Dodson. 2004. Sauropoda. pp. 259–322 in D. B. Weishampel, P. Dodson and H. Osmólska (eds.), The Dinosauria, 2nd edition. University of California Press, Berkeley and Los Angeles. 861 pp.
- Wedel, Mathew J., and Michael P. Taylor 2013. Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus. PLOS ONE 8(10):e78213. 14 pages. doi: 10.1371/journal.pone.0078213
- Wilson, Jeffrey A. 2002. Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136:217–276.
Notes
1. There is some skepticism about whether Galileo’s experiment really took place, or was merely a thought experiment. But since the experiment was described by Galileo’s pupil Vincenzo Viviani in a biography written in 1654, I am inclined to trust the contemporary account ahead of the unfounded scepticism of moderns. Also, Viviani’s wording, translated as “Galileo showed this by repeated experiments made from the height of the Leaning Tower of Pisa in the presence of other professors and all the students” reads like a documentary account rather than a romanticization. And a thought experiment, with no observable result, would not have demonstrated anything.
2. Earlier experiments had similarly shown that Aristotle’s gravitational theory was wrong, including in the works of John Philoponus in the sixth century — but Aristotle’s orthodoxy nevertheless survived until Galileo.
Sauropod Vertebra Picture of the Week 