It pays to stay humble before nature

April 17, 2018

At the 2011 sauropod gigantism symposium in Bonn, John Hutchinson gave a talk on biomechanics of large animals. At the end he showed a short video of a rhino running full-tilt, tripping, and literally flipping end over end. After the wipeout, the rhino got up and trotted off, apparently unhurt. I don’t remember John’s exact words, but they were something like, “We have no idea how this happens – all our models suggest that rhino should be a pile of broken bones.”

His point was, there is a lot we don’t yet understand, and it pays to keep that in mind.

This morning Mike and I were discussing the Middlesborough meteorite, which fell to ground in front of some railway workers in 1881 and was reported be warm to the touch right after falling. Here’s a short, lightly-edited recap of our conversation.

Mike: If it had slowed to such a very mundane speed, due to atmospheric braking, how on earth was it only “new-milk warm” to the touch?

Me: You mean, since it was obviously melted to hell on its way in, how did it cool down so much? From what I’ve been able to find out so far, most small meteors that survive to hit the ground have finished aerobraking when they’re still about 50,000 feet up, and from there they experience a “dark fall” where they’re just a chunk of rock falling at terminal velocity. It’s pretty cold at 25,000 feet, much less 50,000 feet, so I assume a lot of the heat is pulled away by convection into cold air during the dark fall period. There are meteorites that have fallen onto lake or sea ice and not produced any apparent melting, so at least some of them do fall cold.

Mike: This makes sense. So we imagine that is was a lot hotter than that a short time before the impact, but that it cooled as it continued to fall.

This is an interesting example of how thoroughly physical intuition can mislead when you’re dealing with objects operating in unfamiliar realms: very big (e.g. the K/Pg impactor “splashing”), very small (e.g. insects “swimming” through air) or very fast (e.g. this meteorite’s temperature). Physics works over a huge range, and we only have developed intuition for a small sub-range.

Me: Your point about physics is well taken. The older I get, the more humility I have before nature, after seeing many, many things that I would have thought impossible.

The specific example I had in mind there was digging dinosaurs – if you’d asked me back when if any dinosaurs made burrows, I would have bet heavily against it. And yet, there they are.

Stay humble, folks. It’s weird out there.

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11 Responses to “It pays to stay humble before nature”

  1. Brad Lichtenstein Says:

    The deep space rock was also very cold, near background temp save sun warming. Apparently only the outer surface chars, given poor rock heat conduction:
    https://what-if.xkcd.com/28/

    As for the rhino, I assume the models don’t have a lot of bone elasticity, let along ligament, and how forces are transmitted within what amounts to a slightly stiffened liquid bag and not a rigid skeleton.

    Nor did the video show the embarrassed rhino hiding before bellowing in pain…

  2. Mike Taylor Says:

    I’m sure you’re 100% on soft tissue (and bone elasticity, too, for that matter). When I started working on dinosaurs, I only knew skeletons, and my whole mental model of how whole animals worked mechanically was way over-simplified: basically, bones as compression members and tendons and muscles as tension members. Once I started actually cutting up dead critters it immediately became very apparent that animals are both tougher and much more complex than I’d realised. Every palaeontologist should have to take apart a decent-sized animals before they write any papers about anatomy :-)

  3. Kenneth Carpenter Says:

    What you say is most certainly true. The same should be said about anyone attempting to mount a fossil skeleton. The worse mounts are those done in ignorance of basic vertebrate functional morphology. I STILL cannot believe why sauropods (ad other dinosaurs) are mounted with their coracoids so far apart.

  4. Mike Taylor Says:

    Or (a pet favourite) with the bony distal end of the femur directly meeting the bony proximal end of the tibia — rather than the bones being separate by the very substantial cartilage that would most certainly have been present. (You only need to serve up a roast chicken to see this.)

  5. Eric Says:

    But can we see that rhino video? (For science, I mean. Serious science.)

  6. Mike Taylor Says:

    I’d love to see it again, but I’ve not been able to find it. John, do you have it?

  7. Mike Taylor Says:

    Update! John posted the video on Twitter: https://twitter.com/JohnRHutchinson/status/986866145348259840

    I’ll see if I can embed it in the post.

  8. Kenneth Carpenter Says:

    That’s cool. I note that 1) the landscape looks like a game park, with yard grass, 2) that the rhinos are young, but not babies, 3) that the they seem to be playing (note when the one stumbles, the farthest rhino makes like it is going to poke it several times – also note it wags its tail), 4) that they gallop off as if in chase, with the same lead individual. Soft tissue has a lot of cushion effect, so I am not floored by the video.

  9. Kenneth Carpenter Says:

    I guess it is more accurate to call it a zoological park, not game park. It looks like big San Diego Zoo Safari Park based on the topography, grass, and trees. And they have young white rhinos there (Nikita Kahn Rhino Rescue Center). Google it and you will see.

  10. Marja Erwin Says:

    I have tools to block animated gifs, but without these tools, animated gifs trigger my migraines, and some can trigger some people’s seizures. I think the problems are that they animate without warning, that many flash, and that most flash as they loop.

  11. Eric Says:

    Mike — science everywhere thanks you. (Rhinos everywhere go “ow!”.)


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