I recently discovered the blog Slime Mold Time Mold, which is largely about the science of obesity — a matter of more than academic interest to me, and if I may say to, to Matt.

I discovered SMTM through its fascinating discussions of scurvy and citrus-fruit taxonomy. But what’s really been absorbing me recently is a series of twenty long, detailed posts under the banner “A Chemical Hunger“, in which the author contests that the principle cause of the modern obesity epidemic is chemically-induced changes to the “lipostat” that tells our bodies what level of mass to maintain.

I highly recommend that you read the first post in this series, “Mysteries“, and see what you think. If you want to read on after that, fine; but even if you stop there, you’ll still have read something fascinating, counter-intuitive, well referenced and (I think) pretty convincing.

Anyway. The post that fascinates me right now is one of the digressions: “Interlude B: The Nutrient Sludge Diet“. In this post, the author tells us about “a 1965 study in which volunteers received all their food from a ‘feeding machine’ that pumped a ‘liquid formula diet’ through a ‘dispensing syringe-type pump which delivers a predetermined volume of formula through the mouthpiece'”, but they were at liberty to choose how many hits of this neutral-tasting sludge they took.

This study had an absolutely sensational outcome: among the participants with healthy body-weight, the amount of nutrient sludge that they chose to feed themselves was almost exactly equal in caloric content to their diets before the experiment. But the grossly obese participants (weighing about 400 lb = 180 kg), chose to feed themselves a tiny proportion of their usual intake — about one tenth — and lost an astonishing amount of weight. All without feeling hunger.

Please do read the Slime Mold Time Mold write-up for the details. But I will let you in right now on the study’s very very significant flaw. The sample-size was two. That is, two obese participants, plus a control-group of two healthy-weight individuals. And clearly whatever conclusion we can draw from a study of that size is merely anecdotal, having no statistical power worth mentioning.

And now we come to the truly astonishing part of this. It seems no-one has tried to replicate this study with a decent-sized sample. The blog says:

If this works, why hasn’t someone replicated it by now? It would be pretty easy to run a RCT where you fed more than five obese people nutrient sludge ad libitum for a couple weeks, so this means either it doesn’t work as described, or it does work and for some reason no one has tried it. Given how huge the rewards for this finding would be, we’re going to go with the “it doesn’t work” explanation.

In a comment, I asked:

OK, I’ll bite. Why hasn’t anyone tried to replicate the astounding and potentially valuable findings of these studies? It beggars belief that it’s not been tried, and multiple times. Do you think it has been tried, but the results weren’t published because they were unimpressive? That would be an appalling waste.

The blog author replied:

Our guess is that it simple hasn’t been tried! Academia likes to pretend that research is one-and-done, and rarely checks things once they’re in the literature. We agree, someone should try to replicate!

I’m sort of at a loss for words here. How can it possibly be that, 58 years after a pilot study that potentially offers a silver bullet to the problem of obesity, no-one has bothered to check whether it works? I mean, the initial study is so old that Revolver hadn’t been released. Yet it seems to have just lain there, unloved, as the Beatles moved on through Sergeant Pepper, the White Album, Abbey Road et al., broke up, pursued their various solo projects, died (50% of the sample) and watched popular music devolve into whatever the heck it is now.

Why aren’t obesity researchers all over this?

This recent news story tells of a cane toad found in Australia that weighs six pounds. Here’s the photo, because it’s too good not to include:

Kylee Gray, a ranger with the Queensland Department of Environment and Science, holds a giant cane toad, Thursday, Jan. 12, 2023, near Airlie Beach, Australia. “We believe it’s a female due to the size, and female cane toads do grow bigger than males. When we returned to base, she weighed in at 2.7kg, (5.95 lbs) which could be a new record”, said Gray. (Queensland Department of Environment and Science via AP)

I am no cane-toad expert, so I am only going on what this news report had to say, but apparently the average weight of a cane toad is about one pound. So this new world-record individual masses six times as much as a typical adult.

Mature male saltwater crocodiles Crocodylus porosus are typically about 4.5 m long, but the world-record verified skull length is 76 cm long indicating a total length of about 7 m. Having a length 1.56 times that of a typical individual, this beast would have massed 1.56^3 = 3.75 times as much.

There may be less variance in mammal sizes. The world-record elephant Satao massed about 11 tonnes. That’s about double the typical adult African elephant mass, which is various reported as 5 or 6 tonnes.

Now think about sauropod sizes. We have a bunch of big Diplodocus specimens all measuring on the order of 25 m in length, and massing perhaps 15 tonnes. If world-record individuals compared to these as world-record elephants do, there would have been Diplodocus individuals of twice that mass (30 tonnes); if they compared as crocs do, we should expect giant specimens massing 3.75 times as much (56 tonnes); and if they compared as cane toads do, then the factor of 6 would give us giant Diplodocus individuals massing 90 tonnes.

All of this is speculative of course — wildly so — because we have such tiny samples of Diplodocus compared with the three extant species discussed above. It’s not remotely surprising that the ten or so specimens we have don’t include a freak like this. But there’s a good chance they were out there.

Oh, and for Brachiosaurus, of which known individuals massed perhaps 30 tonnes, it’s not unreasonable to imagine giant individuals massing 60, 112 or gulp! 180 tonnes. Yes, the imagination balks at the idea of a 180-tonne land animal: but that alone is not reason enough to discount the possibility.

Michelle Stocker with an apatosaur vertebra (left) and a titanosaur femur (right), both made from foam core board.

In the last post I showed the Brachiosaurus humerus standee I made last weekend, and I said that the idea had been “a gleam in my eye for a long time”. That’s true, but it got kicked into high gear late in 2021 when I got an email from a colleague, Dr. Michelle Stocker at Virginia Tech. She wanted to know if I had any images of big sauropod bones that she could print at life size and mount to foam core board, to demonstrate the size of big sauropods to the students in her Age of Dinosaurs course. We had a nice conversation, swapped some image files, and then I got busy with teaching and kinda lost the plot. I got back to Michelle a couple of days ago to tell her about my Brach standee, and she sent the above photo, which I’m posting here with her permission.

That’s OMNH 1670, a dorsal vertebra of the giant Oklahoma apatosaurine and a frequent guest here at SV-POW!, and MPEF-PV 3400/27, the right femur of the giant titanosaur Patogotitan, from Otero et al. (2020: fig. 8). (Incidentally, that femur is 236cm [7 feet, 9 inches] long, or 35cm longer than our brachiosaur humerus.) For this project Michelle vectorized the images so they wouldn’t look low-res, and she used 0.5-inch foam core board. She’s been using both standees in her Age of Dinosaurs class at VT (GEOS 1054) every fall semester, and she says they’re a lot of fun at outreach events. You can keep up with Michelle and the rest of the VT Paleobiology & Geobiology lab group at their research page, and follow them @VTechmeetsPaleo on Twitter.

Michelle’s standees are fully rad, and naturally I’m both jealous and desirous of making my own. I’ve been wanting a plywood version of OMNH 1670 forever. If I attempt a Patagotitan femur, I’ll probably follow Michelle’s lead and use foam core board instead of plywood — the plywood Brach humerus already gets heavy on a long trek from the house or the vehicle.

Speaking of, one thing to think about if you decide to go for a truly prodigious bone is how you’ll transport it. I can haul the Brach humerus standee in my Kia Sorento, but I have to fold down the middle seats and either angle it across the back standing on edge, or scoot the passenger seat all the way forward so I can lay it down flat. I could *maybe* get the Patagotitan femur in, but it would have to go across the tops of the passenger seats and it would probably rest against the windshield.

Thierra Nalley and me with tail vertebrae of Haplocanthosaurus (smol) and the giant Oklahoma apatosaur (ginormous), at the Tiny Titan exhibit opening.

As long as I’m talking about cool stuff other people have built, a formative forerunner of my project was the poster Alton Dooley made for the Western Science Center’s Tiny Titan exhibit, which features a Brontosaurus vertebra from Ostrom & McIntosh (1966) blown up to size of OMNH 1331, the largest centrum of the giant Oklahoma apatosaurine (or any known apatosaurine). I wouldn’t mind having one of those incarnated in plywood, either.

I’ll bet more things like this exist in the world. If you know of one — or better yet, if you’ve built one — I’d love to hear about it.


  • Alejandro Otero , José L. Carballido & Agustín Pérez Moreno. 2020. The appendicular osteology of Patagotitan mayorum (Dinosauria, Sauropoda). Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2020.1793158
  • Ostrom, John H., and John S. McIntosh. 1966. Marsh’s Dinosaurs. Yale University Press, New Haven and London. 388 pages including 65 absurdly beautiful plates.

I have long intended to write a paper entitled Why Elephants Are So Small, as a companion piece to Why Giraffes Have Short Necks (Taylor and Wedel 2013). I’ve often discussed this project with Matt, usually under the acronym WEASS, and its substance has come up in the previous post, and especially Mickey Mortimer’s comment:

I think it would be interesting to read a study on that — the order in which various factors restrict body size without transformative adaptations. Similarly, what the differences would be for an aquatic animal like a whale.

That is exactly what the WEASS project was supposed to consist of: a list of many candidate limitations on how big animals can get, some rough attempt to quantify their Big-O behaviour, some discussion of which factors seems to limit the sizes of modern terrestrial animals, and how dinosaurs (especially sauropods) worked around those limitations.

(Whales are different. I have in my mind a half-formed notion for a third paper, completing the trilogy, with a title along the lines of Why Whales Are Dirty Cheaters.)

What are those candidate limitations? Off the top of my head:


  • Bone strength
  • Cartilage strength
  • Cartilage thickness
  • Muscle strength
  • Nerve length and conduction time


  • Blood pressure: column height and capillary length
  • Lung capacity
  • Tracheal dead space
  • Digestive efficiency
  • Metabolic overheating

Those are just some of the physical limits. There is anecdotal evidence that elephants are not very close to their mechanical limits in their usual behaviour: they could get bigger, and still work mechanically. (Follow the link at the start of this paragraph. You will thank me.)

There are plenty of other factors that potentially limit organism size, including:


  • Feeding rate
  • Ability to navigate dense environments
  • Predator avoidance with limited athleticism
  • Difficulties in mating


  • Territory requirement
  • Time taken to reach reproductive maturity
  • Reproductive rate
  • Birth size
  • Lack of selection pressure: when there are no predators bigger than a lion, why would elephants need to evolve larger size?

I’m sure I am missing loads. Help me out!

I am haunted by something Matt wrote a while back when we were discussing this — talking about how alien sauropods are, and how easily we slip into assuming mammal-like paradigms.

We are badly hampered by the fact that all of the 250kg+ land animals are mammals. We only get to see one way of being big, and it’s obviously not the best way of being big. Our perceptions of how hard it is to be big are shaped by the animals that are bad at it.

So having written this blog post, I am wondering whether it’s time to breathe life back into this project, started in 2009 and repeatedly abandoned.

Small and large sauropods, with cross-sections through neck and leg. Bone shown in white, gullet in yellow. Modified from Twemoji12 1f995 (CC By 4.0) from the Twitter Emoji project. Downloaded from https://commons.wikimedia.org/wiki/File:Twemoji12_1f995.svg

Consider a small sauropod of length x, as shown on the left above. Its mass is proportional to x cubed, it stands on leg bones whose cross-sectional area is x squared, and it ingests food through a gullet whose cross-sectional area is x squared. Now consider a larger sauropod of length 2x, as shown on the right above. Its mass is proportional to 2x cubed = 8x, it stands on leg bones whose cross-sectional area is 2x squared = 4x, and it ingests food through a gullet whose cross-sectional area is 2x squared = 4x. The bigger sauropod has to carry proportionally twice as much mass on its leg bones, and ingest proportionally twice as much food through its gullet. (Similarly, a 104-foot tall gorilla, 20 times as tall as a real one, is only 400 times as strong but 8000 times as heavy — which is why we can’t have Skull Island.)

In practice, big animals tend to have adaptations such as thicker limb bones that mean the numbers aren’t quite as bad as this, but the principal holds: the bigger an animal gets, the worse the problems imposed by scaling. It’s not possible to “solve” this problem because so many biological properties scale this way. Something is always the limiting factor. Suppose it were leg-bones or gullet. If somehow a hypothetical ultra-sauropod evolved extra thick leg-bones and gullet, scaling of respiration would suffocate it, or scaling of digestion would starve it, or scaling of heat-loss through the skin would boil it. The fundamental reason that you can’t just scale an animal up is that some parts of its function scale with volume while most — respiration, digestion, etc. — scale with surface area.

Figure 3. BIBE 45854, articulated series of nine mid and posterior cervical vertebrae of a large, osteologically mature Alamosaurus sanjuanensis. Series is estimated to represent the sixth to fourteenth cervical vertebrae. A, composite photo-mosaic of the cervical series in right lateral view; identification of each vertebra indicated by C6 to C14, respectively. B, line drawing based on the photo-mosaic in A. C, line drawing in B with labels shown and vertebral fossae indicated by solid grey fill; cross-hatching represents broken bone surfaces and reconstructive material. Abbreviations: C, cervical vertebra; cdf, centrodiapophyseal fossa; clf, centrum lateral fossa; pocdf, postzygapophyseal centrodiapophyseal fossa; prcdf, prezygapophyseal centrodiapophyseal fossa; prcdf1, dorsal prezygapophyseal centrodiapophyseal fossa; prcdf2, ventral prezygapophyseal centrodiapophyseal fossa; sdf, spinodiapophyseal fossa; spof, spinopostzygapophyseal fossa; sprf, spinoprezygapophyseal fossa. (Tykoski and Fiorillo 2016)

Have you been reading Justin Tweet’s series, “Your Friends the Titanosaurs“, at his awesomely-named blog, Equatorial Minnesota? If not, get on it. He’s been running the series since June, 2018, so this notice is only somewhat grotesquely overdue. The latest installment, on Alamosaurus from Texas and Mexico, is phenomenal. I have never seen another summary or review that pulled together so much of the relevant literature and explained it all so well. Seriously, that blog post deserves to be a review paper; it could be submitted pretty much as-is, although it would be even better with his two other Alamosaurus posts integrated (this one, and this one). It’s great work, is what I’m saying, and it needs to be acknowledged.

In particular, I was struck by the note by Anonymous in 1941 on the discovery of a cervical vertebra 1.2 meters long. I’d never heard of that ref, and I’ve never seen that vert, but at 120cm it would be in the top 7 longest cervical vertebrae on the planet (see the latest version of the list in this post), narrowly beating out the 118-cm cervical of Puertasaurus. In fairness, the preserved cervical of Puertasaurus is probably a posterior one, and more anterior cervicals might have been longer. Then again, in the big Alamosaurus neck the longest verts are pretty darned posterior, so…we need more Puertasaurus.

EDIT a few hours later: Thanks to the kind offices of Justin Tweet, I’ve now seen Anonymous (1941), and the exact wording is, “A single vertebra, or neck joint bone, is three feet across, only two inches less than four feet long, and in its present fossilized state weighs 600 pounds.” ‘Two inches less than four feet long’ is 46 inches or a hair under 117cm, which puts the supposed giant cervical just behind Puertasaurus after all, but still firmly in the top 10. And depending on how one interprets the passage in Anonymous (1941), it might not have been any bigger than BIBE 45854–see this comment for details.

Big cervical showdown. From the top left: BYU 9024, originally referred to Supersaurus but more likely representing a giant Barosaurus (137cm); the single available cervical of Puertasaurus (118cm); a world-record giraffe neck (2.4m); Alamosaurus referred cervical series BIBE 45854, longest centra are ~81cm; Sauroposeidon holotype OMNH 53062, longest centrum is 125cm. This image makes it very clear that whatever Sauroposeidon was doing, it was a way different thing from Alamosaurus.

Crucially, the longest vertebrae in the BIBE 45854 series are about 80 or 81 cm long, which means that a 1.2-meter cervical would be half again as large. That is a pretty staggering thought, and that individual of Alamosaurus–assuming it was the same taxon as BIBE 45854, and not some other, longer-necked critter–would definitely be a contender for the largest sauropod of all time.

Illustrations here are of the big Alamosaurus cervical series from Big Bend, which was comprehensively described by Ron Tykoski and Tony Fiorillo in 2016, and which we have covered in these previous posts:


  • Anonymous. 1941. Find dinosaur neck bone nearly four feet long. The Science News-Letter 39(1):6–7.
  • Tykoski, R.S. and Fiorillo, A.R. 2016. An articulated cervical series of Alamosaurus sanjuanensis Gilmore, 1922 (Dinosauria, Sauropoda) from Texas: new perspective on the relationships of North America’s last giant sauropod. Journal of Systematic Palaeontology 15(5):339-364.

I got a wonderful surprise a couple of nights ago!

Supersaurus referred scapulocoracoid BYU 12962 back when it was still in the ground. Rough composite assembled from screenshots of the video below, from about 23m17s.

I found myself wondering where the widely quoted (and ludicrous) mass estimate of 180 tons for Ultrasauros came from, and went googling for it. That took me to a blog-post by Brian Switek, which linked to a Google Books scan of what turned out to be my own chapter on the history of sauropod research (Taylor 2010) in the Geological Society’s volume Dinosaurs and Other Extinct Saurians: a Historical Perspective. So it turns out that I once knew the answer to that question. My chapter references McGowan (1991:118), which says:

Jim Jensen’s (1985) Ultrasaurus (“beyond lizard”), found in Colorado in 1979, had an estimated length of more than ninety-eight feet (30 m), compared with seventy-four feet (22.5 m) for the Berlin specimen of Brachiosaurus. This is a length increase of 1.32, so the weight increase would be (1.32)^3 = 2.3, giving an estimated weight of almost 180 tons.

[As I noted in my 2010 chapter, that’s based on Colbert’s (1962) equally silly estimate of 78 tonnes for MB.R.2181 (formerly HMN S II), the Girafatitan brancai paralectotype.]

So that’s a funny story and a mystery solved, but where it gets really good is that as I was grubbing around in the search results that led me to that conclusion, I stumbled on Episode 21 of the I Know Dino podcast, which contains a glorious embedded video: The Great Dinosaur Discovery, a 1976 film by BYU about Jensen’s work at quarries including Dry Mesa, and heavily featuring bones of what would become Supersaurus!

It’s very well worth 25 minutes of your time, despite the horrible 1970s documentary music, and brings actual new information to the table.

Some of the highlights include:

— Right from the start, seeing Jensen himself: someone I’ve been sort of familiar with from the literature, but never really imagined as being an actual human being.

— From about two minutes in, Jensen seems be uncovering bones in dry sand, rather like kids in a palaeo pits at some museums. It takes about one minute to uncover a nice tibia. Is it ever really that easy? Is the Dry Mesa quarry that easy to work?

— Putting faces to the important names of Vivian and Eddie Jones, the uranium prospectors who first led Jensen to several of his important sites, and after whom the species Supersaurus vivianae and Dystylosaurus edwini were named.

Vivian “Supersaurus” Jones and Eddie “Dystylosaurus” Jones in the field [from about 4m41s in the video]

— From about 13m30s onwards, we see what I think must be the Supersaurus pelvis that’s now on display at the North American Museum of Ancient Life. (It doesn’t actually look all that big, in the scheme of things.)

— From 16m50s onwards, things start to get real, with the uncovering (real or re-enacted) of the first Supersaurus scapulocoracoid: that is, the one that Jensen referred to in his 1985 paper as “first specimen”, but which in the end he did not designate as the holtotype. This bone, once accessioned, became BYU 12962 (but Jensen refers to it in his papers as BYU 5501).

The first appearance in the film of the Supersaurus scap BYU 12962 fully unconvered [18m11s]. You can easily recognise it as the bone that Jensen posed with from the lobe-shaped acromion process.

— Within seconds of our seeing the scap, Jensen decides the best thing to do is illustrate how it’s “like a sidewalk” by walking up and down on it. Seriously.

Oh, Jim.

— At about 19m30s, we see what is probably the big Barosaurus vertebra BYU 9024 whose identity Jensen changed his mind about a couple of times. Unfortunately, the film quality is very poor here, and you can’t make much out.

— From 20 minutes in, the video shows comparative skeletal reconstructions of Brontosaurus (clearly from Marsh 1891), “Brachiosaurus” [i.e. Giraffatitan] (clearly from Janensch 1950) and Supersaurus. The fascinating thing is that the latter is restored as a brachiosaurid — in fact, as a scaled-up Janensch-1950 Giraffatitan with some tweaks only to the head and anterior neck. So it seems Jensen thought at this time that he’d found a giant brachiosaur, not a diplodocid. (Note that this film was made three years before the Ultrasaurus scapulocoracoid was discovered in 1979, so the presumed brachiosaurid identity cannot have rested in that.)

Brontosaurus (yellow), Brachiosaurus (blue), and Supersaurus (white) — which is restored as a brachiosaurid.

— During this section, a fascinating section of narration says “The animal found here is so much larger than anything ever dreamed of, the press, for lack of scientific name, called it a Supersaurus.” If this is legit, then it seems Jensen is not guilty of coining this dumb name. It’s the first I’ve heard of it: I wonder if anyone can corroborate?

— As 22m06s we are told: “It was an AP newsman who broke the story to the world. Time and Life followed. Reader’s Digest ran the story. And National Geographic, one of the quarry sponsors, began an article.” I would love to get hold of the AP, Time, Life and National Geographic articles. Can anyone help? It seems that all these organisations have archives online, but they all suffer from problems:

Here’s that scap again, in the process of being excavated. [22:05]

— As 22m40s, Jack McIntosh turns up to give an expert opinion. I don’t know how much film of him there is out there, but it’s nice that we have something here.

Everyone’s favourite avocational sauropod specialist, Jack McIntosh.

— At 23:17, we get our best look at the scap, with a long, slow pan that shows the whole thing. (That’s the sequence that I made the composite from, that we started this whole post with.)

All in all, it’s a facinating insight into a time when the Dry Mesa quarry was new and exciting, when it was thought to contain only a single giant sauropod, when that animal was known only informally as “Supersaurus” having been so nicknamed by the media, and when it was (it seems) thought to be brachiosaurid. Take 25 minutes, treat yourself, and watch it.

Update (the next day)

The Wikipedia entry on Jim Jensen says that “In 1973, Brigham Young University cooperated with producer Steve Linton and director John Linton in order to produce The Great Dinosaur Discovery, a 1-hour-long color documentary showing Jensen’s on-site finds in Dry Mesa. […] the full-length documentary was reduced to a 24-minute-long mini-film which started airing on American television channels throughout the USA as of 1976.”

Can anyone confirm that the original date was 1973, and not 1976 as given on the short version that’s linked above?

And, more important, does anyone have access to the full-hour version?




In part 2, we concluded that BYU 9024, the large cervical vertebra assigned by Jensen to the Supersaurus holotype individual, is in fact a perfectly well-behaved Barosaurus cervical — just a much, much bigger one than we’ve been used to seeing. Although we heavily disclaimered our size estimates, Andrea Cau quite rightly commented:

Thanks for the disclaimer: unfortunately, it is going to be ignored by the Internet.
So, my boring-conservative mind asks: what is the smallest size that is a valid alternative explanation? I mean, if we combine all possible factors (position misinterpretation, deformation effects, allometry and so on) what could be the smallest plausible size? Only the latter should be taken as “the size” of this animal, pending more material.

Andrea is right that we should take a moment to think a bit more about the possible size implications of BYU 9024.

BYU 9024, the huge cervical vertebra assigned to Supersaurus but which is actually Barosaurus, in left dorsolateral view, lying on its right side with anterior to the right. In front of it, for scale, a Diplodocus cervical from about the same serial position. (Note that the Diplodocus vertebra here appears proportionally bigger than it really is, due to being much closer to the camera.)

What we know for sure is that the vertebra is 1380 mm long (give or take a centimeter or two due to the difficulties of measuring big complex bones in an objective way, something we should write about separately some time.)

We are 99% certain that the bone is a Barosaurus cervical.

We are much less certain about the serial position of that bone. When we were at BYU, we concluded that it most resembled C9 of the AMNH specimen, but I honestly can’t remember the detail of our reasoning (can you, Matt?) and our scanned notebooks don’t offer much in the way of help. We know from McIntosh (2005) that the neural spine of C8 is unsplit and that C9 has the first hint of a cleft.  How does that compare with BYU 9024? Here’s a photo to help you decide:

BYU 9024, large cervical vertebra in left dorsolateral view, inverted (i.e. with dorsal towards us and anterior to the right). Note the shallow cleft between metapophyses at bottom left.

And here’s an anaglyph, to help you appreciate the 3D structure. (Don’t have any red-cyan glasses? GET SOME!)

BYU 9024, oriented similarly to the previous photograph.

The morphology around the crown of the neural spine is difficult to interpret, partly just because the fossil itself is a bit smashed up and partly because the bone, the (minimal) restoration and the matrix are such similar colours. But here’s my best attempt to draw out what’s happening, zoomed in from last non-anaglyph photo:

As you start at the prezygapophyses and work backwards, the SPRLs fade out some way before you reach the crown, and disappear at or before what appears to be an ossified midline ligament scar projecting anteriorly from very near the top of the vertebra. Posterior to that are two small, tab-like metapophyses that appear almost like separate osteological features.

Now this is a very strange arrangement. Nothing like it occurs in any of the cervicals of Diplodocus, where all the way from C3 back to the last cervical, the SPRLs run continuously all the way up from the prezygs to the metapophyses:

Hatcher (1901:plate V). Diplodocus carnegii holotype CM 84, cervical vertebra 2-15 in anterior view.

What we’d love to do of course is compare this morphology with a similar plate of the AMNH Barosaurus cervicals in anterior view, but no such plate exists and no such photos can be taken due to the ongoing entombment of the vertebrae. So we’re reduced to feeding on scraps. McIntosh (2005:47) says:

The neural spine of cervical 8 is flat across the top, and that of cervical 9 shows the first trace of a divided spine (Fig. 2.2A). This division increases gradually in sequential vertebrae, being moderately developed in cervicals 12 and 13, and as a deep V-shape in cervicals 15 and 16.

Sadly, McIntosh illustrates only cervicals 8 and 13 in anterior view: Fig 2.2A does not illustrate C9, as the text implies. And neither of the illustrated vertebrae much resembles what we see in BYU 9024.

So while in 2016 we interpreted BYU 9024 is having “the first trace of a divided spine”, we do hold open the possibility that what we’re seeing is a vertebra in which the spine bifurcation is a little more developed than we’d realised, but with strange morphology that does not correspond closely to any well-preserved vertebra we’ve seen of any sauropod. (Most Barosaurus cervicals are either crushed and damaged; the well preserved ones outside of the AMNH walkway tomb are from a more anterior part of the neck where there is no bifurcation of the spine.)

There is one more possibility. Here is a truly lovely (privately owned) Barosaurus cervical in the prep lab at the North American Museum of Ancient Life (NAMAL):

Uncrushed Barosaurus cervical vertebra, serial position uncertain, in the NAMAL prep lab.

In this blessedly undistorted vertebra, we can see that the summit of the neural spine is flared, with laterally projecting laminae that are likely homologous with metapophyses. (The vertebra is symmetrical in this respect.) Might it be possible that the tab-like metapophyses of BYU 9024 were like this in life, but have been folded upwards post-mortem?

All of this leaves the serial position of the vertebra far from certain. But what we can do is compare it with the lengths of all the known AMNH Barosaurus vertebrae. Columns 1 and 2 in the table below show the serial position and total length of the AMNH cervicals. Column 3 shows the factor by which the 1370 mm length of BYU 9024 exceeds the relevant cervical, and column 4 shows the corresponding estimate for total neck length, based on 8.5 m (Wedel 2007:206–207) for AMNH Barosaurus.

Cv# Length (mm) BYU 9224 ratio BYU 9024 neck length
8 618 2.217 18.84
9 685 2.000 17.00
10 737 1.859 15.80
11 775 1.768 15.03
12 813 1.685 14.32
13 850 1.612 13.70
14 865 1.584 13.46
15 840 1.631 13.86
16 750 1.827 15.53

So to finally answer Andrea’s question from waaay back at the start of this post, the smallest possible interpretation of the BYU 9024 animal gives it a neck 1.584 times as long as that of the AMNH individual, which comes out around 13.5 m (and implies a total length of maybe 43 m).

But I don’t at all think that’s right: I am confident that the serial position of BYU 9024 is some way anterior to C14, likely no further back than C11 — which gives us a neck at least 15 m long (and a total length of maybe 48 m and a mass of maybe 12 × 1.768^3 = 66 tonnes).



  • Hatcher, Jonathan B. 1901. Diplodocus (Marsh): its osteology, taxonomy and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63 and plates I-XIII.
  • McIntosh, John S. 2005. The genus Barosaurus Marsh (Sauropoda, Diplodocidae). pp. 38-77 in: Virginia Tidwell and Ken Carpenter (eds.), Thunder Lizards: the Sauropodomorph Dinosaurs. Indiana University Press, Bloomington, Indiana. 495 pp.
  • Wedel, Mathew J. 2007. Postcranial pneumaticity in dinosaurs and the origin of the avian lung. Ph.D dissertation, Integrative Biology, University of California, Berkeley, CA. Advisors: Kevin Padian and Bill Clemens. 290 pages.

In a comment on the last post, Mike wrote, “perhaps the pneumaticity was intially a size-related feature that merely failed to get unevolved when rebbachisaurs became smaller”.

Caudal pneumaticity in saltasaurines. Cerda et al. (2012: fig. 1).

Or maybe pneumaticity got even more extreme as rebbachisaurids got smaller, which apparently happened with saltasaurines  (see Cerda et al. 2012 and this post).

I think there is probably no scale at which pneumaticity isn’t useful. Like, we see a saltasaurine the size of a big horse and think, “Why does it need to be so pneumatic?”, as if it isn’t still one or two orders of magnitude more massive than an ostrich or an eagle, both of which are hyperpneumatic even though only one of them flies. Even parakeets and hummingbirds have postcranial pneumaticity.

Micro CT of a female Anna’s hummingbird. The black tube in the middle of the neck is the supramedullary airway. Little black dots in the tiny cervical centra are air spaces.

We’re coming around to the idea that the proper way to state the dinosaur size question is, “Why are mammals so lousy at being big on land?” Similarly, the proper way to state the pneumaticity question is probably not “Why is small sauropod X so pneumatic?”, but rather “Why aren’t some of the bigger sauropods even more pneumatic?”

Another thought: we tend to think of saltsaurines as being crazy pneumatic because they pneumatized their limb girdles and caudal chevrons (see Zurriaguz et al. 2017). Those pneumatic foramina are pretty subtle – maybe their apparent absence in other sauropod clades is just because we haven’t looked hard enough. Lots of things have turned out to be pneumatic that weren’t at first glance – see Yates et al. (2012) on basal sauropodomorphs and Wedel and Taylor (2013b) on sauropod tails, for example.

Back of the skull of a bighorn sheep, showing the air spaces inside one of the broken horncores.

Or, even more excitingly, if the absence is genuine, maybe that tells us something about sauropod biomechanics after all. Maybe if you’re an apatosaurine or a giant brachiosaurid, you actually can’t afford to pneumatize your coracoid, for example. One of my blind spots is a naive faith that any element can be pneumatized without penalty, which I believe mostly on the strength of the pneumatic horncores of bison and bighorn sheep. But AFAIK sauropod girdle elements don’t have big marrow cavities for pneumaticity to expand into. Pneumatization of sauropod limb girdles might have come at a real biomechanical cost, and therefore might have only been available to fairly small animals. (And yeah, Sander et al. 2014 found a pneumatic cavity in an Alamosaurus pubis, but it’s not a very big cavity.)

As I flagged in the title, this is noodling, not a finding, certainly not certainty. Just an airhead thinking about air. The comment thread is open, come join me.


An important paper is out today: Carpenter (2018) names Maraapunisaurus, a new genus to contain the species “Amphicoelias fragillimus, on the basis that it’s actually a rebbachisaurid rather than being closely related to the type species Amphicoelias altus.

Carpenter 2018: Figure 5. Comparison of the neural spine of Maraapunisaurus fragillimus restored as a rebbachisaurid (A), and the dorsal vertebrae of Rebbachisaurus garasbae (B), and Histriasaurus boscarollii (C). Increments on scale bars = 10 cm.

And it’s a compelling idea, as the illustration above shows. The specimen (AMNH FR 5777) has the distinctive dorsolaterally inclined lateral processes of a rebbachisaur, as implied by the inclined laminae meeting at the base of the SPOLs, and famously has the very excavated and highly laminar structure found in rebbachisaurs — hence the species name fragillimus.

Ken’s paper gives us more historical detail than we’ve ever had before on this enigmatic and controversial specimen, including extensive background to the excavations. The basics of that history will be familiar to long-time readers, but in a nutshell, E. D. Cope excavated the partial neural arch of single stupendous dorsal vertebra, very briefly described it and illustrated it (Cope 1878), and then … somehow lost it. No-one knows how or where it went missing, though Carpenter offers some informed speculation. Most likely, given the primitive stabilisation methods of the day, it simply crumbled to dust on the journey east.

Carpenter 2018: Frontispiece. E. D. Cope, the discoverer of AMNH FR 5777, drawn to scale with the specimen itself.

Cope himself referred the vertebra to his own existing sauropod genus Amphicoelias — basically because that was the only diplodocoid he’d named — and there it has stayed, more or less unchallenged ever since. Because everyone knows Amphicoelias (based on the type species A. altus) is sort of like Diplodocus(*), everyone who’s tried to reconstruct the size of the AMNH FR 5777 animal has done so by analogy with Diplodocus — including Carpenter himself in 2006, Woodruff and Foster (2014) and of course my own blog-post (Taylor 2010).

(*) Actually, it’s not; but that’s been conventional wisdom.

Ken argues, convincingly to my mind, that Woodruff and Foster (2014) were mistaken in attributing the great size of the specimen to a typo in Cope’s description, and that it really was as big as described. And he argues for a rebbachisaurid identity based on the fragility of the construction, the lamination of the neural spine, the extensive pneumaticity, the sheetlike SDL, the height of the postzygapophyses above the centrum, the dorsolateral orientation of the transverse processes, and other features of the laminae. Again, I find this persuasive (and said so in my peer-review of the manuscript).

Carpenter 2018: Figure 3. Drawing made by E.D. Cope of the holotype of Maraapunisaurus fragillimus (Cope, 1878f) with parts labeled. “Pneumatic chambers*” indicate the pneumatic cavities dorsolateral of the neural canal, a feature also seen in several rebbachisaurids. Terminology from Wilson (1999, 2011) and Wilson and others (2011).

If AMNH FR 5777 is indeed a rebbachisaur, then it can’t be a species of Amphicoelias, whose type species is not part of that clade. Accordingly, Ken gives it a new generic name in this paper, Maraapunisaurus, meaning “huge reptile” based on Maraapuni, the Southern Ute for “huge” — a name arrived at in consultation with the Southern Ute Cultural Department, Ignacio, Colorado.

How surprising is this?

On one level, not very: Amphicoelias is generally thought to be a basal diplodocoid, and Rebbachisauridae was the first major clade to diverge within Diplodocoidae. In fact, if Maraapunisaurus is basal within Rebbachisauridae, it may be only a few nodes away from where everyone previously assumed it sat.

On the other hand, a Morrison Formation rebbachisaurid would be a big deal for two reasons. First, because it would be the only known North American rebbachisaur — all the others we know are from South America, Africa and Europe. And second, because it would be, by some ten million years, the oldest known rebbachisaur — irritatingly, knocking out my own baby Xenoposeidon (Taylor 2018), but that can’t be helped.

Finally, what would this new identity mean for AMNH FR 5777’s size?

Carpenter 2018: Figure 7. Body comparisons of Maraapunisaurus as a 30.3-m-long rebbachisaurid (green) compared with previous version as a 58-m-long diplodocid (black). Lines within the silhouettes approximate the distal end of the diapophyses (i.e., top of the ribcage). Rebbachisaurid version based on Limaysaurus by Paul (2016), with outline of dorsal based on Rebbachisaurus; diplodocid version modified from Carpenter (2006).

Because dorsal vertebrae in rebbachisaurids are proportionally taller than in diplodocids, the length reconstructed from a given dorsal height is much less for rebbachisaurs: so much so that Ken brings in the new version, based on the well-represented rebbachisaur Limaysaurus tessonei, at a mere 30.3 m, only a little over half of the 58 m he previously calculated for a diplodocine version. That’s disappointing for those of us who like our sauropods stupidly huge. But the good news is, it makes virtually no difference to the height of the animal, which remains prodigious — 8 m at the hips, twice the height of a giraffe’s raised head. So not wholly contemptible.

Exciting times!