I’m not the scientist here at all, but I’ve occasionally watched the series just to learn more about what the current views of evolution are, since they are in a lay-friendly format and when a topic piques my interest.
But if you haven’t noticed, they do provide reference links to all the related papers in each video. There are about a dozen in that video’s description. (You have to scroll down quite a ways.) I haven’t watched this one yet.
The presenter made mention of experts subscribing to the hypothesis that primitive lungs derived from exaptation of swim bladders, but this appears to be wrong because lungs were present long before swim bladders came along. In fact, it appears swim bladders evolved from primitive lungs in our fishy ancestors. In other words, modern swim bladders and modern lungs are descended from primitive lungs.
This error makes me more skeptical of the other claims in the video I couldn’t verify. However, its a fun and simple presentation with cool graphics and an alluring presenter, that really makes you appreciate your fishy ancestors for simply trying to breathe.
Swim bladders would seem to be an actinopterygian invention, and there is a placoderm fossil showing preserved lungs. I would definitely like to see the primary literature that’s the source of the video’s claims that swim bladders came first. Consider also that the supposition that lungs originated in the neighborhood of Eusthenopteron is contradicted by the fact that modern Dipnoi have lungs too. Nice pictures, though. And the position of the spiracle is an interesting point I hadn’t been aware of.
No. The last person I know of who claimed that lungs might have evolved from swim bladders was Charles Darwin. The phylogeny of fish has been well enough settled for at least 50 years, and the placoderm with lungs was discovered long ago too.
But now I see that the latter is controversial and may be untrue:
Still, there was plenty of evidence for lungs → swim bladders long before 2018, and I don’t know of anyone in the last hundred years (in the primary literature, that is) who proposed otherwise.