No-one knows whether or not a neutral-tasting nutrient-sludge diet leads to enormous weight loss
February 15, 2023
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?
I’m sure you’ve seen things like ChatGPT in the news: programs that can carry out pretty convincing conversations. They are known as Large Language Models (LLMs) and are frequently referred to as being Artificial Intelligence (AI) — but I really don’t like that designation as it implies some understanding.
To try this out, I asked OpenAI Chat this question: “What are the contenders for the title of Biggest Dinosaur, and what is the basis for their various claims?” I picked that because I know a bit about the answer, and in fact wrote an answer myself back in 2015.
Here’s what it came up with:
There are several contenders for the title of “biggest dinosaur,” and their claims are based on different pieces of evidence. The most commonly cited contenders are:
- Argentinosaurus: This is considered to be one of the largest known dinosaurs, with estimates of its length ranging from 110-130 feet (33-40 meters) and a weight of around 100-110 tons. Its size is based on a few fragmented bones, including vertebrae and limb bones, which were found in Argentina.
- Brachiosaurus: This dinosaur is estimated to have been around 85 feet (26 meters) long and weighed around 80-100 tons. Its size is based on several well-preserved specimens that have been found in North America, including a nearly complete skeleton.
- Puertasaurus: This dinosaur is estimated to have been around 85-100 feet (26-30 meters) long and weighed around 80-100 tons. Its size is based on a few bones, including a femur, that were found in Argentina.
- Supersaurus: This dinosaur is estimated to have been around 110-125 feet (33-38 meters) long and weighed around 80-100 tons. Its size is based on a single specimen, a set of vertebrae, that was found in the US.
- Diplodocus: This dinosaur is estimated to have been around 90-115 feet (27-35 meters) long and weighed around 20-40 tons. Its size is based on several well-preserved specimens that have been found in North America.
It’s worth noting that the size of these dinosaurs is approximate and there’s still debate among paleontologists. Also, the weight of these dinosaurs is based on estimations, not real measurements.
At first glance this is a decent answer. It’s certainly better than just saying “Argentinosaurus weighed 100 tons”. But if you know your sauropods, you’ll immediately recognise that this answer is riddled with inaccuracies:
- The Argentinosaurus entry is actually pretty good, although I’ve never seen a 110 ton mass estimate and modern estimates tend to be rather lower than the specified range.
- The Brachiosaurus mass estimate is way off, two or three times as high as it should be.
- More importantly, no remotely complete Brachiosaurus specimen has ever been described, and size estimates are based primarily on its Tanzanian relative Giraffatitan.
- There is no known femur of Puertasaurus. (When I corrected the AI on this, it told me instead that there is a pubis known.)
- Supersaurus is not based on a single specimen, and both of the main specimens that have been described contain plenty of appendicular material.
- The Diplodocus length estimate is a bit inflated, but otherwise not bad. But it’s not clear what it’s doing in a list of five biggest dinosaurs.
- The answer omits some very strong contenders, including Dreadnoughtus and Patagotitan.
- It doesn’t really address the second part of my question — e.g. Supersaurus has a good claim to be longer, but not heaviest; the converse is likely true for Argentinosaurus.
Now here is the real problem: the LLM does well enough to fool people. If it was nonsense from start to end, there would be nothing to fear here, but the plausibility of the answers and the authoritative tone in which they are given lends the many mistakes a credibility that they do not deserve.
Having seen this sort-of-convincing-but-very-wrong reply in a field that I know something about, I would be very very cautious about trusting an LLM to teach me about a field I don’t already know. I’m guessing its replies about space flight, quantum physics and Medieval French literature are going to be similarly flawed (but also, worryingly, similarly convincing to those such as myself who don’t know better.)
There is a very fundamental reason for all these mistakes: as I implied above, LLMs do not understand anything. They just know what phrases occur close to other phrases. They can do amazing things with that one trick, and I can see them being useful as discovery tools. But we’ll go badly wrong when we start trusting them as anything more than a bright but ignorant kid offering suggestions.
So for all the talk of AI having taken huge leaps forward in the last couple of years, I don’t think any such thing has happened. We’ve just got much better at generating plausible text. But there’s no advance in actual understanding.
Matt and I are writing a paper about Barosaurus cervicals (yes, again). Regular readers will recall that the best Barosaurus cervical material we have ever seen was in a prep lab for Western Paleo Labs. We have some pretty good photos, such as this one:
Barosaurus cervical vertebra lying on its right side in anterodorsal view (i.e. with dorsal to the left), showing the distinctive shape of the prezygapophyseal rami.
The problem is that this specimen was privately owned at the time we saw it, and so far as we know it still is. So according to all standard procedures, we should consider it unavailable to science until such time as it is deposited in an accredited museum. (I was pretty sure the SVP has an explicit policy to this effect, but I couldn’t find it on the site. Can anyone?)
So what should we do? All the possible courses of action seem unfortunate.
1. We could go ahead and include photos, drawings and descriptions of these vertebrae in the paper — but that would violate community norms by building an argument on observations that cannot be in general be replicated by other researchers. (For all we know, these vertebrae are now decorating Nicolas Cage’s pool room.)
2. We could omit these vertebrae from the paper, but use the information we gained from examining them in formulating our diagnostic criteria for Barosaurus cervicals — but this would also not really be replicable, plus it would have that horrible “we know something that you don’t” quality.
3. We could act as though these vertebrae do not exist, or as though we had never seen them, writing the paper based only on our observations of inferior material and of the good AMNH 6341 that is not accessible for study or photography — but that would make our characterisation of Barosaurus cervical morphology less helpful than it could be.
4. We could refrain from publishing on Barosaurus cervicals at all until such time as these vertebrae, or similarly well-preserved ones, are available to study at accredited institutions — but that would simply deprive the world of an interesting and exciting study.
Is there a fifth path that we have not seen? And if not, which of these four is the least objectionable?
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.
How stupid was the neck of Camarasaurus?
February 19, 2021
What if I told you that when Matt was in BYU collections a while ago, he stumbled across a cervical vertebra — one labelled DM/90 CVR 3+4, say — that looked like this in anterior view?
I think you would say something like “That looks like a Camarasaurus cervical, resembling as it does those illustrated in the beautiful plates of Osborn and Mook (1921)”. And then you might show me, for example, the left half of Plate LXII:
And then you might think to yourself that, within its fleshy envelope, this vertebra might have looked a bit like this, in a roughly circular neck:
Reasonable enough, right?
But when what if I then told you that in fact the vertebra was twice this wide relative to its height, and looked like this?
I’m guessing you might say “I don’t believe this is real. You must have produced it by stretching the real photo”. To which I would reply “No no, hypothetical interlocutor, the opposite is the case! I squashed the real photo — this one — to produce the more credible-seeming one at the top of the post”.
You would then demand to see proper photographic evidence, and I would respond by posting these three images (which Matt supplied from his 2019 BYU visit):
BYU specimen DM/90 CVR 3+4, cervical vertebra of ?Camarasaurus in anterior view. This is the photo from which the illustration above was extracted.
The same specimen in anteroventral view.
The same specimen in something approaching ventral view.
So what’s going on here? My first thought was that this speicmen has to have been dorsoventrally crushed — that this can’t be the true shape.
And yet … counterpoint: the processes don’t look crushed: check out the really nice 3d preservation of the neural spine metapophyses, the prezygs, the transverse processes, the nice, rounded parapophyseal rami, and even the ventral aspect of the centrum. This vertebra is actually in pretty good condition.
So is this real? Is this the vertebra more or less as it was in life? And if so, does that mean that the flesh envelope looked like this?
Look, I’m not saying it isn’t ridiculous; I’m just saying this seems to be more or less where the evidence is pointing. We’ve made a big deal about how the necks of apatosaurines were more or less triangular in cross-section, rather than round as has often been assumed; perhaps we need to start thinking about whether some camarasaur necks were squashed ovals in cross section?
Part of what’s crazy here is that this makes no mechanical sense. A cantilevered structure, such as a sauropod neck, needs to be tall rather than wide in order to attain good mechanical advantage that can take the stress imposed by the neck’s weight. A broad neck is silly: it adds mass that needs to be carried without providing high anchors for the tension members. Yet this is what we see. Evolution doesn’t always do what we would expect it to do — and it goes off the rails when sexual selection comes into play. Maybe female camarasaurus were just really into wide-necked males?
Final note: I have been playing fast and loose with the genus name Camarasaurus and the broader, vaguer term camarasaur. Matt and I have long felt (without having made any real attempt to justify this feeling) that Camarasaurus is way over-lumped, and probably contains multiple rather different animals. Maybe there is a flat-necked species in among them?
(Or maybe it’s just crushing.)
Why do people publish in Scientific Reports?
April 25, 2020
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:
- PeerJ: $1,195 APC (or free if authors are members)
- PLOS ONE: $1,695 APC
- Scientific Reports: $1,870 APC
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.
Shoebills lie tell the truth (and it’s disgusting)
January 27, 2020
Heinrich Mallison sent me this amazing photo, which he found unattributed on Facebook:
Infuriatingly, I’ve not been able to track down an original source for this: searching for the text just finds a bunch of reposts on meme sites, and Google’s reverse image search just reports a bunch of hits on Reddit:
The line-drawing shows some scientific understanding of bird skeletons, so I imagine someone put real thought into this and is unhappy that the image is propagating uncredited. If that person reads this, please leave a comment: I’d love to credit it properly.
Anyway … what’s going on here?
Birds (like all vertebrates) have two tubes running down the ventral aspect of the neck (i.e. below the vertebrae): the trachea, for breathing, and the oesophagus, for swallowing. But these both open into the back of the mouth and are not piped up past it. I’ve not dissected enough bird heads to show this clearly, but when I was taking Veronica apart the trachea was pretty visibly ending in the mouth cavity, not plumbed up past the mouth into the nasal space:
So yes, I think it’s true: shoebills can bulge their spines out of their mouths.
Why? My best guess that there’s just nowhere else for the spine to go when the neck is retracted. There’s a big empty space in the mouth, why let it go to waste?
My sauroponderous birthday card from Brian Engh
June 3, 2019
Okay, so here on the Best Coast it’s not technically my birthday for another 3 hours, but SV-POW! runs on England time, and at the SV-POW! global headquarters bunker it’s already June 3. Oh, and tomorrow Brian and I are driving to New Mexico to look for Cretaceous monsters with Andrew McDonald and crew, and I won’t be advantageously situated for blogging. So here’s my Favorite. Card. EVAR:
Apatosaurus is — still — Just Plain Wrong
November 30, 2018
We’ve posted a lot here about how crazy the cervical vertebrae of apatosaurines are (for example: 1, 2, 3), and especially the redonkulosity of their cervical ribs. But I think you will agree with me that this is still an arresting sight:
That’s MWC 1946, a mid-cervical from the Mygatt-Moore Quarry that was figured by Foster et al. (2018: fig. 18 A-B) and referred with the rest of the Mygatt-Moore apatosaur material to Apatosaurus cf. louisae (entirely correctly, in my view). This is a ventral view, with the condyle down by the scale bar.
Here’s the same thing cropped from the background to emphasize its unbelievableness:
and mirrored and restored a bit in GIMP to give a taste of its probable appearance in life (if you had an apatosaur, an x-ray machine, and a lot of confidence about not getting stepped on):
For obvious reasons, my nickname for this specimen is the Brontosmasher.
Keep in mind that the centrum was full of air in life, whereas the cervical ribs and the bony struts that support them are just huge slabs of bone. I strongly suspect that the volume of bone in the cervical ribs and their supporting struts is vastly more than in the centrum and neural arch. I will soon have the ability to test that hypothesis–I have this specimen on loan from Dinosaur Journey for CT scanning and 3D modeling. Watch this space.
Many thanks to Julia McHugh at Dinosaur Journey for access to the specimen and assistance during my frequent visits.
Reference
- Foster, J.R., Hunt-Foster, R.K., Gorman, M.A., II, Trujillo, K.C., Suarez, C.A., McHugh, J.B., Peterson, J.E., Warnock, J.P., and Schoenstein, H.E. 2018. Paleontology, taphonomy, and sedimentology of the Mygatt-Moore Quarry, a large dinosaur bonebed in the Morrison Formation, western Colorado—implications for Upper Jurassic dinosaur preservation modes: Geology of the Intermountain West 5: 23–93.
How crazy are the cervicals of Mendozasaurus?
February 1, 2018
There’s a new paper out, describing the Argentinian titanosaur Mendozasaurus in detail (Gonzalez Riga et al. 2018): 46 pages of multi-view photos, tables of measurement, and careful, detailed description and discussion. But here’s what leapt out at me when I skimmed the paper:
Gonzalez Riga et al. (2018: figure 6). Mendozasaurus neguyelap cervical vertebra (IANIGLA-PV 076/1) in (A) anterior, (B) left lateral, (C) posterior, (D) right lateral, (E) ventral and (F) dorsal views. Scale bar = 150 mm. Sorry it’s monochrome, but that’s how it appears in the paper.
Just look at that thing. It’s ridiculous. In our 2013 PeerJ paper “Why Giraffes have Short Necks” (Taylor and Wedel 2013), we included a “freak gallery” as figure 7: five very different sauropod cervicals:
Taylor and Wedel (2013: figure 7). Disparity of sauropod cervical vertebrae. 1, Apatosaurus “laticollis” Marsh, 1879b holotype YPM 1861, cervical ?13, now referred to Apatosaurus ajax (see McIntosh, 1995), in posterior and left lateral views, after Ostrom & McIntosh (1966, plate 15); the portion reconstructed in plaster (Barbour, 1890, figure 1) is grayed out in posterior view; lateral view reconstructed after Apatosaurus louisae (Gilmore, 1936, plate XXIV). 2, “Brontosaurus excelsus” Marsh, 1879a holotype YPM 1980, cervical 8, now referred to Apatosaurus excelsus (see Riggs, 1903), in anterior and left lateral views, after Ostrom & McIntosh (1966, plate 12); lateral view reconstructed after Apatosaurus louisae (Gilmore, 1936, plate XXIV). 3, “Titanosaurus” colberti Jain & Bandyopadhyay, 1997 holotype ISIR 335/2, mid-cervical vertebra, now referred to Isisaurus (See Wilson & Upchurch, 2003), in posterior and left lateral views, after Jain & Bandyopadhyay (1997, figure 4). 4, “Brachiosaurus” brancai paralectotype MB.R.2181, cervical 8, now referred to Giraffatitan (see Taylor, 2009), in posterior and left lateral views, modified from Janensch (1950, figures 43–46). 5, Erketu ellisoni holotype IGM 100/1803, cervical 4 in anterior and left lateral views, modified from Ksepka & Norell (2006, figures 5a–d).
But this Mendozasaurus vertebra is crazier than any of them, with its tiny centrum, its huge, broad but anteroposteriorly flattened neural spine, and its pronounced lSPRLs.
I just don’t know what to make of this, and neither does Matt. And part of the reason for this may be that neither of us has had that much to do with titanosaurs. As Matt said in email, “Those weird ballooned-up neural spines in titanosaurs kind of freak me out.” And I could not agree more.
And of course as sauropodologists, we really should familiarise ourselves with titanosaurs. There are a lot of them, and they account for a lot of sauropod evolution. Someone recently made the point, either in an SV-POW! comment or on Facebook, that titanosaurs may be to sauropods what monkeys and apes are to primates: a subclade that is way more diverse than the rest of the clade put together.
It’s starting to look like an extreme historical accident that Camarasaurus, diplodocines and brachiosaurids — all temporally and/or geographically restricted groups — were the first well-known sauropods, and for decades defined our notion of what sauropods were like. Meanwhile, the much more widespread and long-surviving rebbachisaurs and titanosaurs were poorly understood until really the last 25 years or so. For the first century of sauropodology, our ideas about sauropods were driven by weird, comparatively short-lived outliers.
That our appreciation of titanosaur diversity has come so late says something about how our discovery of the natural world is more to do with geopolitics and the quirks of exploration than what’s actually out there. Sauropods were defined by diplodocids for so long because that’s what happened to be in the ground in the exposed rocks of North America, and that’s where the well-funded museums and expeditions were.
We at SV-POW! towers have often wondered how different our idea of what dinosaurs even were would be if the Liaoning deposits had been available to Buckland, Mantell, and Owen. It seems like that unavoidable that, if they’d first become familiar with feathered but osteologically aberrant (by modern standards) birds, one of two things would have happened. Either they would either have never coined the term “Dinosauria” at all, recognizing that Megalosaurus (and later Allosaurus and Tyrannosaurus) were just big versions of their little feathered ur-birds. Or they would have included Dinosauria as a primitive subclass of Aves.
References
- González Riga, Bernardo J., Philip D. Mannion, Stephen F. Poropat, Leonardo D. Ortiz David and Juan Pedro Coria. 2018. Osteology of the Late Cretaceous Argentinean sauropod dinosaur Mendozasaurus neguyelap: implications for basal titanosaur relationships. Zoological Journal of the Linnean Society, 46 pages, 28 figures. doi:10.1093/zoolinnean/zlx103
- Taylor, Michael P., and Mathew J. Wedel. 2013. Why sauropods had long necks; and why giraffes have short necks. PeerJ 1:e36. 41 pages, 11 figures, 3 tables. doi:10.7717/peerj.36
Note. This post contains material from all three of us (Darren included), harvested from an email conversation.
Sauropod Vertebra Picture of the Week 