Fighting apatosaur art #3: Bob Nicholls

September 25, 2015

On the morning of Tuesday 1st December, on SVPCA day 1, I gave my talk about apatosaur neck combat. In one of the afternoon sessions, I sat next to Bob Nicholls, and found myself thinking how awesome it would be if he sketched some apato-combat.

But I didn’t want to come right out and say “Hey, Bob, how ’bout you spontaneously illustrate our palaeobiological hypothesis?” So instead I used a tactic that Fiona often uses when she wants me to do something: she starts to do it herself, badly, and waits for me to take over. (This is often how I find myself cooking in the evenings.) In the same spirit, sat next to Bob, I started a horrible sketch of wrestling apatosaurs. Sure enough, Bob, saw what I was doing, internally decided it ought to be done properly, and produced this:

WrestleBronto2a (c)Nicholls2015

What I love most about this (beside the casual way he knocked it out in fifteen minutes) is the sense of heft about the apatosaurs. These are big, solid animals. Someone’s gonna get hurt.

 

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21 Responses to “Fighting apatosaur art #3: Bob Nicholls”

  1. dmaas Says:

    wait, there’s something missing…. where’s yours!?

  2. Mike Taylor Says:

    It’s coming … but you won’t like it.

  3. Frosted Flake Says:

    The most impressive part is how right the idea seems.

    Obviously, Bulls competed just as usually happens. The one who can get higher can smash down on his rival. Of course, he would have to be bigger -or have a longer neck- to do that. (Gee, I wonder why these guys had such long necks) Being bigger and/or longer would mean he is the big guy. If that is the metric of mating fitness for them then giantism seems the reasonable outcome. And giantism is THERE, reinforcing the ‘bigger lizard contest’ hypothesis. Food is less an issue for cold blooded kind, and bulk conserves heat for nocturnal activity. So being that big would not have the high maintenance costs a warm blooded critter would need to pay, every day. I wonder how many calories they would need.

    And it had to wait for someone to notice the peculiar unexplained morphology of Apatosaurus cervical bones for this extinct behavior to more or less explain itself.

    Well done. It is fun to watch you guys work.

  4. Mike Taylor Says:

    Thanks!

    Note, though, that we only see evidence for this kind of behaviour in apatosaurs. Other sauropods’ necks are not similarly reinforced, and we reject the idea that sexual selection is the reason for sauropods’ long necks.

    On metabolism: anyone who thinks sauropods were cold-blooded has to explain how they were able to grow at the same rate as elephants. To my mind, the evidence says they were tachymetabolic endotherms.

  5. Frosted Flake Says:

    Tachymetabolic. But not homeothermic? No big heat shedding sail, like Spinosaurus has.

    https://en.wikipedia.org/wiki/Spinosaurus

    Am I nuts to think those spines were about temperature control?

  6. Mike Taylor Says:

    I am taking it as read that we all agree sauropods were homeothermic. The issue under dispute (though I don’t think it’s very controversial) is how that constant body temperature was achieved. Mass homeothermy would be one explanation that allows sauropods to be bradymetabolic ectotherms; but I don’t think it flies, because you just can’t get the growth rate without a fast metabolism.

    Sails on spinosaurs: the problem with hypothesising temperature control is that then you have to explain how all the other dinosaurs managed to control their temperatures without a sail. It seems more likely that whatever spinosaurs were doing with their sails was something unique to them. Which most likely means they were a sexual signal, I guess.

  7. Frosted Flake Says:

    Thanks for this discussion. I am learning some new words.

    Re : Spiny. I noted he was a Sahara fish hunter. That would expose him to the Sun while he conducts his business. And fish are fast, so Spiny probably had to work for it at times. I supposed this was not the usual way Theropods did things. (Sneak up, charge, have lunch) And I noted Spiny was huge. Such bulk would retain heat and high activity would generate heat. From there it seems a very small supposition to connect the unusual sail with temperature control in the unusual conditions.

    I also reflected on the human hunting technique of keeping the prey on the move until heat stroke sets in. We can do this only because we sweat. So we can get rid of the heat. So we can be active in extreme temperatures I’ve had heat stroke a couple times. I don’t recommend it. A sail seems a more convenient place to rapidly dump heat than through the big theropods brain. And I supposed the evolutionary advantage would be, what terrible things might happen to a big hunter while incapacitated because too hot?

    You figure not, though.

  8. Mike Taylor Says:

    Carcharodontosaurus, in the same size-class as Spinosaurus, lived in the same time and place, and had no sail. Evidently didn’t need one. You suggest that fish-hunting might be more energetically demanding than terrestrial hunting; but even if that were true (which it probably isn’t — consider a heron’s lifestyle), spending time in water gives Spino a perfect heatsink. It’s the one theropod that (based on diet) we can be confident didn’t need to carry its own heatsink around.


  9. Would Spino sitting in cold water all the time be a reason to have a sail sticking up into the sun? Kind of a heat-soak instead of a heat-sink?

  10. Mike Taylor Says:

    Nice try, but no :-) Lots of animals spend lots of time in water, both endotherms (seals, dolphins) and ectotherms (crocs, turtles). None of them, in any area of the world, needs a sail to keep warm.

  11. nwfonseca Says:

    Is there any way to test which direction the necks might best withstand the stress? I.e. laterally or vertically? I know you guys aren’t overly fond of F.E.A, but would something akin to that help in predicting the direction of the neck to neck contact? Or does it not really matter the direction and it was just overall massing in all directions to resist forces in all directions?

  12. Mike Taylor Says:

    You mean to determine whether ventral-to-ventral or ventral-on-dorsal contact was used? No, I can’t imagine a way to test that with any rigour. (The problem with FEA is that, because you make a model and feed it to a computer and get numbers out, it produces the illusion of rigour whether or not the model actually means anything.)

    In any case, we just don’t have sufficiently complete necks to model properly.


  13. I love watching this brontosaur neck-combat idea coming together. It makes sense, and I love the idea of big soft-tissue structures reinforcing the underside of the neck.

    Four years ago, I’d be sketching this too. Alas, no longer. But I’ll enjoy watching other, more talented people draw it.

  14. Matt Wedel Says:

    nwfonseca asked:

    Is there any way to test which direction the necks might best withstand the stress? I.e. laterally or vertically?

    Sure, just look at the necks. Anterior cervicals tend to have the cervical ribs displaced ventrally, posterior cervicals have them displaced both ventrally and laterally. Of the two, the ventral displacement seems to be more important since it’s more consistently expressed along the length of the neck.

    Techniques like geometric morphometrics and FEA are great for sussing out subtle differences in shape or biomechanical performance, and I’m glad they exist. But there is this rising idea that we can’t know anything about structure or function without doing an analysis. Which is nuts. I had the opportunity to take a geometric morphometrics course from Miriam Zelditch and Don Swiderski when I was at Berkeley. The first thing they said was, “If the shape difference is distinct enough to see with the naked eye, you don’t need GM to ‘prove’ that the two things are different. That’s pointless – just describe the difference you see. Save GM for the hard cases, or for when you need to quantify the difference for some other reason.” (Like this.)

    Also, as Mike said, doing an FEA on a whole apatosaur neck would be cool but it would not be illuminating. None of the available necks are complete, and even if they were, we don’t know enough about the sizes, shapes, and tension loads of the various ligaments, tendons, and muscles to figure out what the stress regime should be. We (= humans) haven’t even done that kind of full-up FEA analysis of the whole neck of an extant critter yet – trying to do one on an extinct animal, where we have no way of evaluating the results, would be not even wrong.

    But that doesn’t mean that we can’t look at the morphology of organisms, living and extinct, and draw reasonable inferences. Which is what we’re trying to do with this apatosaur project.


  15. […] an apatosaur combat in the hope that my horrible drawing would provoke Bob to do a good one. That worked admirably, which means there is no good reason for me to subject you to my own […]


  16. I like that Matt discusses some of his concerns against the detail levels of FEA and GMA in apatosaur necks, and that his concerns are notable and valid. However, I disagree with the general conclusions.

    First off, it’s a matter of the distinction between assuming that the data means something, versus letting the data speak for itself. Both FEA and GMA do the latter; making conclusions like “maybe there were spikes sticking out of the knobs on apatosaur necks” does the former. The former is devoid of any specifics, and while they may be forthcoming, they aren’t compared to how this should be uncovered. And the same is true for discussing tensility of ligaments and tendons, and what levels of strain produce what shapes of or how much bone at attachment sites.

    When dealing with the former arguments, we get the large diversity of ideas about neck positions and attitude in life. when dealing with data analysis, but not specifically GMA – which isn’t suited to this question – we get people talking about strain limits based on models presented. We change the models, and we get different numbers. That’s analysis, and that’s sorely lacking in the other case, where simply making inferences without assessing the quality of those inferences is deemed useful, if not sufficient.

    I think the latter comes a lot from raw descriptive paleontology, wherein simply looking at bones and saying what you think you see is enough. Throw in comparisons, and call it most of a day. We’ve had this since Linnaeus, all the way up through Romer, without much in the way of figuring out why these shapes and relationships exist.

    My concern lies in what happens when you’re doing saying what you see and start talking about what you think, and there analysis seems to end, and that’s part of my issue. Papers endlessly discussing the what and speculating on the why without constraining the latter happen all the time. If the papers Mike dislikes, the “boring” GMA and FEA studies, are bad; then the other, the excessive description of form and inference of function without discussing the relationship between them, are papers I dislike, because they tell me you’re just not trying. Form is intimately related to function; form does not exist in a vacuum. Talking function without discussing the relationship to form, and assessing the hypothesis proposed, is doing less than half the work.

    It’s a bit harsh, but it feels lazy. (And yes, I am currently guilty of this myself.)

  17. Mike Taylor Says:

    Jaime asserts:

    It’s a matter of the distinction between assuming that the data means something, versus letting the data speak for itself. Both FEA and GMA do the latter.

    They absolutely do not.

    FEA produces some numbers, which in some sense “speak for themselves”. But those numbers are the output of an admittedly sophisticated process run against models which are woefully inadequate representations of the true properties of objects with complex internal structure, composed of a material that is itself complex and whose properties vary wildly, and based on shapes which can not be fully known from fossils that are inevitably distorted and incomplete. Oh, and we have no meaningful idea of the size, shape or even topology of the muscles that generated the forces acting on these bones.

    Someone running an honest FEA — with proper error bars propagated through every step of the process — would end up with a result like “The stress on the M. longus colli dorsalis muscle was between 0.001 and 1,000,000 kPa”. It would be true, but completely uninformative — like the molecular clock estimates in Graur and Martin’s 2002 classic “reading the entrails of chickens”, where they propagated error bars through others’ spuriously precise calculations and showed that the arthropod-nematode divergence occurred some time between the origin of the universe and 13 billion years in the future.

    Techniques like finite element analysis certainly have their place; they may even have a place in palaeontology. But understanding the behaviour of apatosaur necks is emphatically not it.

    Reference

    Graur, Dan and Martin, William. 2002. Reading the entrails of chickens: molecular timescales of evolution and the illusion of precision. Trends in Genetics 20(2):80-86.

  18. Mike Taylor Says:

    In a similar spirit, my 2005 Progressive Palaeontology presentation ended up showing that brachiosaurs could have walked without crushing their limb cartilage, and that my figures were probably correct within a factor of 756. (We can probably improve on that pretty significantly, but the truth is we’ll always have a lot of uncertainty in such calculations.)

  19. Hikaru Amano Says:

    Wow…I wish somebody would turn that sketch above into a gouache or acrylic painting. Gives me an idea in my attempt for paleo-art painting…

  20. Mike Taylor Says:

    I wouldn’t rule it out that Bob turns this into a “finished” piece.

    On the other hand, I love the “unfinished” look for sketches like this.

  21. ncmncm Says:

    About error bars — it’s not unreasonable to just add the uncertainty from two calculations, but when you have a long series, law of averages comes into play. Unless there is something systematic, some of the errors go in opposite directions, so total expected error doesn’t grow as fast as it might. Of course, often there is something systematic (cf. crash of 2008) and the most likely source of systematic error is yourself (the second most likely is everyone else).

    But that’s not why I am writing. Rather, with the inflated sacs plastered all over these critters, they would have been like thermos bottles unless they could divert a lot of blood flow to the skin. That seems like a lot to ask of an already overburdened heart.

    I’m asserting priority on tree-climbing ‘pods. You can have cliff-hanging.


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