My synapsid family


Nice image to illustrate a basic cladistic principle. I still get whines from creationists complaining that I said we humans are fish — but that’s just a bigger circle enclosing everyone in this image.

I have no illusions that this will ever sink into the brains of the people who deny it.

Comments

  1. says

    Well sure, and we’re also chordates, deuterostomes, metazoans, eukaryotes, and terrestrial organisms, all of which function on the basis of the DNA-RNA-protein mechanism which means we’re all related by common descent. Simple.

  2. PaulBC says

    The problem I have with this visualization is that the tree and the Venn diagram provide identical information. Having both seems like more of a distraction than aid to comprehension.

  3. wzrd1 says

    @Brony, easy sucks, harder keeps us a bit a head, as we blunder our way to whateverinhell is “the truth”.
    Truth is hard, which is what makes it so valuable!

  4. whheydt says

    Re: Akira MacKenzie @ #6…
    That assumes (a) that your archetypical redneck knows a dimetrodon when he sees one, and (b) that he can pronounce it.

  5. stroppy says

    Yeah, it’s got some design issues. I probably would have gone in a different direction. It’s an intriguing approach, though, so it’s not something I’d discard altogether, just maybe keep it around as something to sort out and repurpose for something else later.

  6. beholder says

    It was important for us that the reader understood, in a visual way, that once you are in a group, you never leave the group.

    Or, as Wikipedia helpfully reminds me when I search for “synapsid”, I am in the same clade as Richard Nixon.

    Never gonna live it down.

  7. whheydt says

    Re: beholder @ #18…
    When Reagan was governor of California, it was claimed that there was an Anthro test extra-credit question…
    True or False: Ronald Reagan is a primate.

  8. khms says

    I undertand the circles-in-circles part, but what the hell is going on in the inner part where there are overlapping circles?!

  9. chrislawson says

    PaulBC@9–

    You would think that creationists would not use that argument, but after the infamous second-law-of-thermodynamics “scientists have not identified that source of energy” quote, I do not believe there is an argument stupid enough that no creationist will propose it. (If anyone can point me to the original quote, I’d appreciate it).

    Don’t forget these are the same buffoons who insist that evolution is far too slow to have created all the diversity of life…while also arguing that evolution is so fast that all current land creatures are descended exactly two specimens from a handful of ‘kinds’/’baramins’ on the Ark…including all trees from flowering gums in outback Australia to conifers in the Arctic Circle that apparently evolved from one ‘kind’ on the Ark 4000 years ago even though there is overwhelming evidence that trees (i.e. tall,woody plants with leaves) evolved independently from several different plant types (cycads from ferns, flowering trees from gymnosperms, lepidondrales from lycopods, calamites from horsetails) rather than a single kind.

  10. birgerjohansson says

    I am glad the illustration includes the dimetrodon,
    Akira MacKenzie@6
    this is one of the iconic early reptiles and I am proud to have it as an evolutionary uncle 😊

  11. birgerjohansson says

    The “sail” on early reptiles can also be found in some early amphibians.
    As ears needed time to evolve once vertebrates left the water, visual signals took the place of “voice ” until ears had evolved enough to cover a wide range of frequences. Thus, the big fin may have been used to signal “I am a healthy male”.
    The presumed ‘sail of the much later spinosaurus might have served the same function as a camel’s hump.
    The feet structures on some fossil species may have served for walking in sand instead of muddy ground.

  12. stroppy says

    khms @ 21

    There are a number of issues with the graphic, but the one that may be most responsible for leading you astray is the heavy white line that encircles everything while also being used to connect species over time. And it’s not just that, it starts out as a straight line crossing circles and then becomes circular when it branches to form connections, somewhat suggesting a circle in the middle that doesn’t exist. The use of color offsets that, but only barely.

    This is why artists need supervision. Their visual thinking is not the same as the visual thinking scientists do.

    I’ll plug the Guild of Natural Science Illustrators here just because sad scientists are busy breaking glassware and need professional help:
    https://www.gnsi.org

  13. PaulBC says

    stroppy@29 It’s a weird graphic, as I said already @10. If you draw lines (edges) between small circles (nodes) you get a tree, and that expresses a hierarchy of subsets very well already–but as you say, maybe not to a visual artist. It is a learned abstraction. Alternatively, drawing a big circle and nested smaller circles instead them (effectively a Venn diagram with only strict subset intersection) will express the same hierarchy, and may be clearer to some people.

    But what I see above is truly bizarre. It’s as if you took the little circles representing tree nodes, expanded their size, and then put the subtree inside the node. I mean, there’s a kind of creative genius to it. I would never have thought of doing it that way. But I also don’t think it’s any more useful as a visualization than the tree or Venn diagram alone.

  14. PaulBC says

    Also, the fact that the subset graph appears at an oblique angle doesn’t help much. My immediate impression that the woman and the prehistoric creatures are about to play a game like hopscotch still holds up. I have to look harder to find the secret message.

  15. stroppy says

    PaulBC @ 31

    “I have to look harder to find the secret message.”

    Bingo! You shouldn’t have to work any harder to analyze the content than is absolutely necessary. If a picture is worth a thousand words, the creator should give it at least as much attention as they would to logic, structure, grammar, word choice, etc. when writing. Graphic literacy is a real thing.

  16. birgerjohansson says

    PaulBC@31
    Stroppy @ 32

    One way to add a third dimension would be to let the purple circle (with the human) be the starting point for the next illustration, showing the relationships between the branches of early proto-mammals (known only from partial jaws and teeth) coexisting with the dinosaurs. The first known instance of inambiguosly preserved hair should be marked.
    The last common ancestor to monotremes, marsupials and placental mammals should be in a circle that serves as the starting point to the third illustration.
    3. The last common ancestor will be shown in its own illustration in relationship with the descendants; marsupials, placental mammals monotremes and sister groups that did not survive the end of the dinosaurs. The multitude of mammalian groups that branched off after the end of the cretaceous are too many to fit inside a clear illustration.

  17. birgerjohansson says

    FYI, one of the most numerous reptiles coexisting with those synapsids were the plant-eating rynchosaurs, belonging to a reptile group I think is extinct.
    The early and mid- permian would not have looked familiar to fans of Jurassic Park.
    If I recall correctly, the first stem-amniotes quickly led to four branches of reptiles; synapsids, wossname ancestors to lizards, wossname ancestors to archosaurs dinosaurs and birds, and a fourth group.
    All these early reptiles were quite primitive when compared to the current reptile species- a time traveller would not have been able to pick out any future “winner”.

  18. PaulBC says

    I grew up reading a kids’ illustrated science encyclopedia in the 70s that had probably been published a good bit earlier, and I swear it was filled with evolutionary trees and timeline charts showing extinction. I don’t recall seeing the word “clade” used, but I did get a clear enough understanding of the difference between “descended from” and “sharing a common ancestor with”. Some large part of the country seems to have gotten dumber about their understanding of evolution since that time.

  19. stroppy says

    birgerjohansson @ 33

    Possibly. I’d have to see it sketched out a bit.

    The salient idea is simple and simply stated

    It was important for us that the reader understood, in a visual way, that once you are in a group, you never leave the group.

    The objective would be to put it in a compact, easy to grasp-at-a-glance form. Not necessarily an easy task.

    At first blush, my inclination would be to work a linear tree in plan view to fit over a layer of crisply defined color patches (without enclosing lines) to constrain groupings. Handling of color would be key but a bit tricky. Another possibility would be to blow up a stack of layers in 3D view so long as you keep the number of elements to a minimum. You really need to sketch it out and play with the particulars to see what can work well and what won’t.

    On one level, tt might help if you think of the process as part art and part what they used to call creating an “engineered document” (in another context).

    Critiquing the original graphic highlights problem areas. For instance, the overall effect of confining the image in a strong circle (with one small line leading out, almost as an afterthought) suggests a closed system, which is disorienting. The overall handling puts an emphasis on a pleasing graphic effect over content. It left me with an impression of pebbles causing ripples that is at odds with how I see evolution moving.

    But that’s just me. For instance, PaulBC had other associations. What people might read into your picture is something a designer should try to trap for as much as possible.

    IMO

  20. stroppy says

    I’ve been having a hard time putting my finger on what my overall problem with the image is. What it comes down to, for me, is that it depicts not leaving a group, but it’s more as a pictorial symbol of the concept than it is a convincing demonstration of how that’s a necessary outcome of the process of evolution. The operative word being ‘convincing’.

  21. PaulBC says

    stroppy@36 I think I’d summarize my complaint as “Just because you can doesn’t mean you should.” It’s kind of cool to have a the subjects of the chart pop out in 3D. If the point is just to have an eye-catching graphic, then sure, they accomplished that. But it’s taken to the point where it stops being a visualization and looks like an illustration. Why on earth are there shadows? This really reinforces the idea of the subjects actually standing in a painted circle for some reason or other.

    Without changing any other aspect of the visualization, simply making it 2D and circular, and superimposing flat pictures of the woman and animals in the appropriate spots would better serve the purpose of revealing the intended abstraction instead of concealing it. Of course, it wouldn’t be as “cool” but that shouldn’t be the point, should it?

    Second, the hybrid tree/Venn diagram serves little purpose. Something like nested circles with labels might work. Or just a friggin’ tree. I know that’s boring and unoriginal, but it’s unoriginal because it works very well.

  22. PaulBC says

    stroppy@37 I think I understand your issue with the enclosing circles, but it didn’t really bother me too much. I look at this as a computer scientist, not a biologist, so when I see an oriented tree, it doesn’t matter much if it is going from left to right, top to bottom, or outside to inside as with the circles. But if the idea is to express a process over a period of time, it’s a little disconcerting to be confined in a smaller and smaller space.

    If the point is that you can’t escape your clade, then a tree expresses this just fine. My descendants all descend from the same ancestors as I did. If you don’t believe it, follow the path up to the root. But maybe some kind of visual reinforcement would help. I just don’t think this is it.

  23. DanDare says

    I got the image instantly and enjoyed its appearance. I might have made the clade lines be distinct from the circles to make it clearer, perhaps making them grey instead of white.

  24. PaulBC says

    DanDare@40

    I got the image instantly and enjoyed its appearance.

    Yeah. I’m just kind of a minimalist party pooper.

  25. stroppy says

    Yes, visual reinforcement.

    I can’t say I know why the point of not being able to escape a group needs to be made. If you’re going to make it though, I think it’s implicit in a tree, so a good solution would be to make it explicit by adding appropriate highlights. That’s sort of what this graphic tries to do, while wandering a little too close to chart junk territory, starting with artistic choices that are at odds with “treeness,” if that makes sense. That’s mainly what all my rambling about circles was about. That and the nested circles need a better, clearer treatment, maybe starting with getting rid of the tilt. That said, you probably wouldn’t end up with circles on a straight line tree so much as polygons. Certainly putting lines around them would just add confusion when blocks of color are sufficient.

    Enough of that. I’m starting to bore even myself.

    As for the upright figures, I guess if you’re going to tilt a map and stick pins in it, without text, they might as well be upright and look like what they’re representing. Since the tilt is a perspective rendering, essentially a scene, might as well give it a light source too.

  26. birgerjohansson says

    Stroppy @ 42
    “…look like what they are representing”.
    Especially the gorgonopsids need more attention to detail, they would look awesome!

  27. stroppy says

    birgerjohansson @ 43

    It’s normal in infographics to simplify like that. Still there’s something about the figures that seems a little off. It might be the color. I see why the designer did it that way but… something.

    Ok, so I can’t let it go. Mainly it’s about why this isn’t a Venn diagram but a cross-section. Think of it as a 3 dimensional tree that’s been bisected perpendicular to the stem with the top removed, the remainder folded over and pressed flat so that you’re looking at a cross section with the stem folded under it — the result then abstracted with critters left sticking up, some from deeper layers.

    It’s a neat idea, but if you’re trying explain a simple idea that some people nevertheless apparently have trouble grasping, this approach almost seems harder to grasp than the actual concept. Maybe it’s just me.

  28. PaulBC says

    stroppy@42

    while wandering a little too close to chart junk territory

    I would say they’ve sailed off to terra incognita unexplored by the likes of USA Today, but again I am just going to be a party pooper. I think a simple tree is already very clear and this one mystifies rather that clarifies. You have to know what you’re supposed to see in order to figure it out.

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