CLADISTICS ruined my life
yall joke but this is actually a serious conundrun with cladistic-based classification
The choice is this:
Birds are reptiles
Or crocodilians (and probably turtles) ARENT
That’s it, that’s the choice
What if Bird and reptiles are two different things that came from the same thing
Nope
Because you can’t group (lizards, snakes, tuatara, turtles, crocodilians) without also including (birds)
So if you don’t want to include birds in reptiles then you have to leave out some things we’ve called reptiles
birds are dinosaurs though, full stop. we’ve already defined what a dinosaur is and it includes birds. but reptiles isn’t really defined so much as thrown against a wall angrily.
But don’t turtles and alligators have more in common with modern reptiles than modern birds have in common with modern reptiles? I’m not trying to contradict, I’m trying to understand. Mammals and reptiles have a common ancestor as well, but we do not make them the same group.
It’s not about having things in common. It’s about common ancestry, which is how we classify animals in light of extinct species, which defy trait-based classification.
And, the common ancestor of [lizards, snakes, tuatara, turtles, crocodilians] by definition is also the common ancestor of birds. It is NOT the common ancestor of mammals.
So, either we decide that Tuatara Lizards and Snakes are the only reptiles, or we include birds as reptiles. Or we just decide reptiles are no longer a thing.
don’t throw reptiles against the wall? please? some of them are small and delicate. you could hurt them.
Basically, unless we’re maybe talking massive horizontal gene transfer, everything is still part of the group that came before it.
You are technically a fish.
IIRC the fish thing is so frustrating that scientists have decided fish is just not real cladistic grouping at all
hey could we go back please to the bit where the closest relative of Birds is Crocodiles? bc I am alarmed
Well, technically they’re equally-closely related to crocodiles, alligators, gharials and tomistomas. As archosaurs, they’re all descended from small reptiles that looked something like this
The two main groups of archosaurs are the Pseudosuchia, or crocodile-line archosaurs, and the Ornithodira, or bird-line archosaurs. Both groups were massively diverse in prehistory, with the Pseudosuchia dominating most land-based niches in the Triassic, and the Ornithodira, especially the dinosaurs, doing the same during the Jurassic and Cretaceous. However, most of them have been wiped out due to the Triassic and Cretaceous mass extinctions, leaving them each with only one surviving clade: Aves, the true birds, and Crocodylia, the semiaquatic, ambush predators like crocs and gators.
This entire post sums up everything we’re not allowed to mention in our Vertebrata classes because the last time someone started that argument they had to break up a fistfight.
I’m just hung up on the humans evolving from fish comment.
Like, we evolved from tiny tree-climbing squirrels. To the best of our knowledge.
…which evolved from tiny tree-climbing reptiles
…which evolved from amphibians
…which evolved from fish.
im sad that ppl of age don’t know we evolved from fish bc that means there’s a HUGE part of our origin- the part where we lived in the sea- that they’re entirely unaware of for some reason. Like all life on earth originated in water. All of it. There weren’t just suddenly squirrels???
Surprised we got this far without mentioning that while cladistically, humans are fish, cladistically, fish are also not a monophylum :)
I.e. have the same problem reptiles have where the concept of a group called “fish” has so many problems that the simplest solution would be to just throw the term out entirely
(Also, shout-out to my old vertebrates class prof who wanted more sci-fi authors to keep in mind a marine evolutionary origin for their alien races)
That face when thinking about all the people who wanna be mermaids is just something deep in your bones wanting to go home -back into the unknown dark abyss of the ocean.