Comment on Why is land/sky so cleanly split between mammals/birds?
InvalidName2@lemmy.zip 1 day ago
The single, simple answer is the one that you don’t want to hear: There is no clean split. Bats are a large and diverse group of flying mammals just like birds are a large and diverse group of flying dinosaurs.
The simplest answer I can come up with (because it’s actually a very complicated and convoluted topic that I wouldn’t truly do just anyway) is: Most birds can fly because they are an offshoot of one group of dinosaurs (avian dinosaurs) that survived the last great extinction when their non-flying non-avian dinosaur relatives did not. Basically the ones that couldn’t fly mostly went extinct. And mammals mostly don’t fly, which is possibly because several groups of vertebrates beat them to it and essentially filled all the niches that would have been available to flying animals, kind of blocking that path for them.
Obviously that’s nowhere near the full story. There are lots of other factors at play, like some of the peculiarities of mammalian and dinosaur physiology that made one group better suited to flight than the other, ramifications of the great extinction that killed non-avian dinosaurs as well as most large animals in general and whole swaths of other species, and so on.
CmdrShepard49@sh.itjust.works 1 day ago
Is this accurate? I was always under the impression that birds evolved from “land dinosaurs”.
Makhno@lemmy.world 1 day ago
Well, yes, where else would the flying dinosaurs come from?
CmdrShepard49@sh.itjust.works 1 day ago
That it was more of a direct path from say raptors to chickens, but I mentioned in another reply that I had forgotten about all the different dinosaur eras and the hundreds of millions of years between them all.
Zagorath@aussie.zone 1 day ago
The first flying dinosaur evolved from a non-flying dinosaur. The word for a “flying dinosaur” is “bird”. (Sort of. Bird isn’t a scientific term, arguably crown-group birds don’t include the first flying dinosaurs. But in that case the first bird evolved from a flying dinosaur which evolved from non-flying dinosaurs, so it still works.)
CmdrShepard49@sh.itjust.works 1 day ago
I guess I’m forgetting that there were several different dinosaur periods spanning hundreds of millions of years. My mind defaults to the jurassic period being the only one.
Zagorath@aussie.zone 1 day ago
Most of the more famous dinosaurs were actually from the cretaceous period. T. rex, stegosaurus, velociraptor (and the deinonychus and utahraptor that the movie Jurassic Park’s depiction of “velociraptor” was based on), triceratops, ankylosaurus. Pretty much all the non-avian dinosaurs the average person could name, other than sauropods like brachiosaurus, lived in the cretaceous. Some of those I named did admittedly first evolve in the jurassic, but most are most well-known in the cretaceous.
Though fwiw, birds did first evolve in the jurassic.
phantomwise@lemmy.ml 1 day ago
I guess that depends on your definition of what’s a bird is and where you place the transition between bird-like dinosaurs and birds. Like Archaeopteryx is one of the species in that weird kinda dinosaur kinda bird phase.