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.

*runs in ten minutes late with a plucked chicken*

BEHOLD A LIZARD

you could have left the feathers on this time tbh

It was already plucked. They just STOLE IT from philosophy 101.

Every turn on this post has been a left, but somehow it hasn’t hit itself, and instead just spiralled outwards like some Ancient Greco-Roman floor design, enveloping taxonomy Tumblr in chaos.

LMFAO

My evolutionary bio professor took the class to a museum of natural science once and pointed out that of, like, a dozen skeletons in the “dinosaur” exhibit only one was actually a dinosaur. There were more dinosaurs next door. In the bird room.

Also: carcinization. Nature loves evolving crabs. What we call “crabs” are actually five different groups that all happened to evolve the same body shape.

Fish didn’t pop out of nowhere either though they evolved from something???

we are all actually a single-celled organism

But if there’s no such thing as a fish, then what did those tree-climbing reptiles evolve from?

The argument is less “fish aren’t real” and more “if fish are real, either you are also a fish–not “you came from a fish”, YOU RIGHT THIS SECOND ARE A FISH RIGHT NOW–or else, if we say that fish are specifically teleost (ray-finned) fishes, that works okay but also? Sharks ain’t fish. Nor coelacanths, nor lungfish. Or lampreys. Or hagfish.

It turns out it is in fact difficult to create a good cladistic group that approximates categorizations that are derived from a combination of linguistics and current phenotypic assessment!

But today’s Sunday.

@anomalouscorvid