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All you are saying is that it is funny that dinosaurs went extinct. Nothing says that an animal with an efficient environmental fit needs to evolve. The evoluti

All you are saying is that it is funny that dinosaurs went extinct. Nothing says that an animal with an efficient environmental fit needs to evolve. The evolution in the arachnid family looks just about as crazy as dinosaurs to birds and alligators https://en.wikipedia.org/wiki/Arachnid#/media/File:Haeckel_Arachnida.jpg https://en.wikipedia.org/wiki/Arachnid#/media/File:Haeckel_A...

baddox 8y ago
I agree with your larger point, but that image isn’t very convincing. All of those arachnids look very similar.
- andrewflnr 8y ago
  I can only imagine someone thinking those all look similar if they had subconsciously blanched at the batshit biodiversity on display and simply lumped them all in the "batshit" category. "Yep, all batshit, no real differences there." Look at the variation in abdominal shape and compare to, say, the variation in overall mammal body plans. I think if you look closer you'll find it stacks up pretty well.
  - baddox 8y ago
    Does it stack up well between dinosaurs and birds though? I mean, I’m nothing close to a zoologist, but even just the size difference among extant birds would strike me as more various than the arachnids in that picture, and that’s without even including dinosaurs.
    - stan_rogers 8y ago
      The largest extant spider (the Goliath birdeater) is well over 300 times the size of the smallest (contested, but take the Patu digua as a reference) as an adult. With the bee hummingbird at about 2 and a quarter inches (~57mm), that would mean the biggest bird would need to be over 60 feet (18.2m) beak-to-tail by your reckoning. And we know of pre-spider critters (more like modern camel spiders than modern true spiders) that were house cat sized, and eurypterids preceding them that were around 8 feet long. And keep in mind that there are constraints on land-dwelling arthropods both to do with support (what do you do when you moult at that size?) and respiration that animals with skeletons, lungs and pneumatic bones don't have to deal with. What's almost funny, given things like pygmy leaf chameleons and fingernail-sized frogs, is that modern birds don't get much smaller than they do. It all comes down to some combination of ignorance (and it's hard to know everything even in your own field, so no need for anyone to get superior or defensive where that's concerned at all) and incredulity. A lot of it is hard to imagine until you take the information that is available and spend some time actually imagining it.
    - andrewflnr 8y ago
      Haeckel wasn't that into rendering his little ensembles to scale, AFAIK. The ones in the corners look like mites, which would mean that picture represents at least two or three orders of magnitude in size variation. But really, the scalar variable of size seems more significant than all the spikes and hairs and scales and whatnot?

baddox 8y ago

I agree with your larger point, but that image isn’t very convincing. All of those arachnids look very similar.

andrewflnr 8y ago
I can only imagine someone thinking those all look similar if they had subconsciously blanched at the batshit biodiversity on display and simply lumped them all in the "batshit" category. "Yep, all batshit, no real differences there." Look at the variation in abdominal shape and compare to, say, the variation in overall mammal body plans. I think if you look closer you'll find it stacks up pretty well.
- baddox 8y ago
  Does it stack up well between dinosaurs and birds though? I mean, I’m nothing close to a zoologist, but even just the size difference among extant birds would strike me as more various than the arachnids in that picture, and that’s without even including dinosaurs.
  - stan_rogers 8y ago
    The largest extant spider (the Goliath birdeater) is well over 300 times the size of the smallest (contested, but take the Patu digua as a reference) as an adult. With the bee hummingbird at about 2 and a quarter inches (~57mm), that would mean the biggest bird would need to be over 60 feet (18.2m) beak-to-tail by your reckoning. And we know of pre-spider critters (more like modern camel spiders than modern true spiders) that were house cat sized, and eurypterids preceding them that were around 8 feet long. And keep in mind that there are constraints on land-dwelling arthropods both to do with support (what do you do when you moult at that size?) and respiration that animals with skeletons, lungs and pneumatic bones don't have to deal with. What's almost funny, given things like pygmy leaf chameleons and fingernail-sized frogs, is that modern birds don't get much smaller than they do. It all comes down to some combination of ignorance (and it's hard to know everything even in your own field, so no need for anyone to get superior or defensive where that's concerned at all) and incredulity. A lot of it is hard to imagine until you take the information that is available and spend some time actually imagining it.
  - andrewflnr 8y ago
    Haeckel wasn't that into rendering his little ensembles to scale, AFAIK. The ones in the corners look like mites, which would mean that picture represents at least two or three orders of magnitude in size variation. But really, the scalar variable of size seems more significant than all the spikes and hairs and scales and whatnot?