cass

assigned catgirl at birth

white, early twenties, disabled, lesbian, plural. a cat that just so happens to be a person. sister of @yrgirlkv. makes things, sometimes.


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yrgirlkv
@yrgirlkv

obviously, this is focused on terrestrial animals; i'm mostly trying to unfuck my head from the linnaean "fish-birds-reptiles-amphibians-mammals" system of my youth by putting each of those groups where they actually belong on the tree of life. please note that i am an enthusiast, not an expert; this is what i, personally, have gleaned from trawling several wikipedia pages on modern evolutionary phylogeny, which is itself a science that's still in flux.

the shape of this diagram, i think, gestures at why you might've seen memes to the effect of "okay, but is there really such thing as a fish?" you can have an informal concept of a fish, sure, and it's a useful one for casual conversation, but there's no evolutionary history that ties all fish together but excludes land animals.

the other thing i think is interesting about this diagram is it conveys just how common convergent evolution really is. dinosaurs and birds are warm-blooded the same as mammals are in spite of having branched off from separate family trees; self-managed thermoregulation is just that useful a strategy for survival. you can see a similar effect in the fact that bats invented flight completely independently of birds, or, for that matter, the fact that birds did it well after pterosaurs had developed flight themselves. at the end of the day, physics constrains the number of useful shapes there are for specific tasks. it really makes me feel what a shame it is that we've never made contact with an alien species, because god i'd love to know how much of this has to do with earth and how much has to do with the rules of the cosmos writ large.

diagram notes:

  1. i truly do mean "most kinds." ray-finned fish are basically almost every species of bony fish you can ever imagine (wikipedia cites a figure of 95%.) the lobe-finned section of this diagram happens to be exhaustive; it's just lungfish, coelacanths, and tetrapods. if you can think of a fish with bones, it's probably a ray-finned one.

  2. "reptile-like" here is a weird way to try and capture something sort of complicated. the earliest synapsids probably looked and worked like modern reptiles, in that they were cold-blooded, layed eggs, etc., but slowly began to evolve mammalian traits over time, like hair, breasts, a tendency towards live births, and so on. modern mammals are the only survivors of the synapsid line; all of those middle-stage species have since died out.


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in reply to @yrgirlkv's post:

my experience with this stuff is mostly just first year college biology stuff where you also learn about all the different methods of differentiating species and how wildly different the results you get can be... it's really cool stuff, there are so many exceptions and complications and scientists are constantly trying to figure out how to fit all of it into something resembling categorization lol

oh big same. i'm still working past biases from back then, when it was all about assigning groups based on phenotype, wherein bats and dolphins were fun exceptions to the typical rule of "if they work the same nowadays they go in the same group." the idea that mammals and dinos arrived at warmbloodedness convergently rather than inheriting it really messes with my head

Back in 2015-16, I got really into trying to categorize animals using yes or no questions as a sort of 20-questions algorithm for animals. I might still have those files around somewhere in my parents' house on an old laptop

The ultimate goal for me was that I'd be able to describe animals in a heavily reduced way using these yes or no questions to define the bits of a genome. It'd start with classifying common animals today, and then I'd use "genetic algorithms" that I had learned about in college to be able to have one "gene pattern" mate with another and evolve some new animal.

I had it in my mind that in doing this, I'd be able to make a more compelling version of Pokémon where the evolution was slightly (and really only just slightly) more science-based

i saw a video recently about how some scientists are beginning to believe that eukaryotes are actually a subgroup of archaeans instead of a distinct domain and that really emphasizes for me how evolutionary biology is held together with classifications we can upend at any time with a single discovery

this is fascinating, thank you! It's so interesting seeing roughly where types branch and traits converge. The development of flight in separate lines is such an interesting occurrence; I'll have to check in with a friend for the title of a book they were reading that went into that as a concept a bit more.