That would mean…not very. Reptiles are an extremely broad and diverse group, containing everything from penguins and crocodiles to tuataras and pythons. Mammals are the most closely-related extant clade that is generally not considered “reptile”, to reptiles.
Arachnids, on the other hand, are more distantly related to insects. Crustaceans form their closest relatives, followed by myriapods (centipedes & millipedes). Only then do arachnids appear.
Yup. Birds are reptiles! If you want to define a monophyletic clade that includes crocodiles and lizards, there is no way to do that without also including birds. To define a clade, you take the evolutionary tree and make a “cut” somewhere on it. Everything below that cut is part of the same clade, you can’t selectively remove some branches but not others, unless it’s by changing where you make your single cut.
So in this diagram:
The green circle notwithstanding, you would usually define reptile as a cut at the “C” on the diagram. You could put the cut at Lepidosauria, but that would mean crocodiles and turtles are no longer considered reptiles either.
A more zoomed-in look would show that after crocodiles and birds branched apart, you also get another branch where pterosaurs branch away from dinosaurs, and that birds are one of many branches and subbranches of dinosaur.
I really appreciate the info and the way you laid it out. Just curious, is that knowledge part of a hobby and/or career? Or was that like just one of the random tidbits you picked up somewhere?
Yeah just a casual interest. Not enough that I’d really call it a hobby, and certainly not a career. But a little more than a few random titbits. This video’s not a bad quick intro to the reasoning I used in my previous comment.
Reptiles, as traditionally defined and therefore as usually meant, do not include birds or mammals. It’s a paraphyletic classification (of which there are boatloads).
Mammals, Birds and therefore non-mammal, non-bird amniotes (reptiles) are class-level classifications, as are insects and arachnids.
Sure, but we’re having this conversation in 2025, after phylogenetic classification has long since taken over as the way we describe the relations between species.
Birds are unambiguously reptiles.
Mammals are not reptiles, but are the most closely-related animals to them.
Who is “we”? It certainly isn’t most people. It’s like these interminable “no such thing as a fish” bollocks. Or “AcKsHuAlLy bananas are berries OHOHOHOHO.”
Keep that kind of jargon for your academic articles. In pop-sci contexts like here, it’s not unreasonable to use, but it deserves a health warning because of the intersection of audiences. Insisting that there’s only one correct usage is insufferable.
What underlying fact does that teach you? Only that botanists categorise fruits a certain way. Learning that word doesn’t teach you anything about bananas, does it?
Well, it taught me that berries have a strict botanical meaning rather than just being and cute little fruit on a bush, and that there can be multiple meanings for a word based on context. There’s nothing wrong with calling a strawberry a berry even while understanding it’s not really a berry. Correctness is important in formal discussions, but we can have fun being intentionally wrong in everyday speech where poetry and history hold more value.
From there one asks, “What is a berry? What about a banana makes it a berry? And what is a strawberry if not a berry?” And so one reads and one learns. “What about a raspberry? What about grapes?” The internet is as forthcoming with answers as one’s brain is with questions.
That would mean…not very. Reptiles are an extremely broad and diverse group, containing everything from penguins and crocodiles to tuataras and pythons. Mammals are the most closely-related extant clade that is generally not considered “reptile”, to reptiles.
Arachnids, on the other hand, are more distantly related to insects. Crustaceans form their closest relatives, followed by myriapods (centipedes & millipedes). Only then do arachnids appear.
Hold on…
Yup. Birds are reptiles! If you want to define a monophyletic clade that includes crocodiles and lizards, there is no way to do that without also including birds. To define a clade, you take the evolutionary tree and make a “cut” somewhere on it. Everything below that cut is part of the same clade, you can’t selectively remove some branches but not others, unless it’s by changing where you make your single cut.
So in this diagram:
The green circle notwithstanding, you would usually define reptile as a cut at the “C” on the diagram. You could put the cut at Lepidosauria, but that would mean crocodiles and turtles are no longer considered reptiles either.
A more zoomed-in look would show that after crocodiles and birds branched apart, you also get another branch where pterosaurs branch away from dinosaurs, and that birds are one of many branches and subbranches of dinosaur.
I really appreciate the info and the way you laid it out. Just curious, is that knowledge part of a hobby and/or career? Or was that like just one of the random tidbits you picked up somewhere?
Yeah just a casual interest. Not enough that I’d really call it a hobby, and certainly not a career. But a little more than a few random titbits. This video’s not a bad quick intro to the reasoning I used in my previous comment.
Reptiles, as traditionally defined and therefore as usually meant, do not include birds or mammals. It’s a paraphyletic classification (of which there are boatloads).
Mammals, Birds and therefore non-mammal, non-bird amniotes (reptiles) are class-level classifications, as are insects and arachnids.
Sure, but we’re having this conversation in 2025, after phylogenetic classification has long since taken over as the way we describe the relations between species.
Birds are unambiguously reptiles.
Mammals are not reptiles, but are the most closely-related animals to them.
Who is “we”? It certainly isn’t most people. It’s like these interminable “no such thing as a fish” bollocks. Or “AcKsHuAlLy bananas are berries OHOHOHOHO.”
Keep that kind of jargon for your academic articles. In pop-sci contexts like here, it’s not unreasonable to use, but it deserves a health warning because of the intersection of audiences. Insisting that there’s only one correct usage is insufferable.
But bananas are berries. It’s fun to learn things.
What underlying fact does that teach you? Only that botanists categorise fruits a certain way. Learning that word doesn’t teach you anything about bananas, does it?
Well, it taught me that berries have a strict botanical meaning rather than just being and cute little fruit on a bush, and that there can be multiple meanings for a word based on context. There’s nothing wrong with calling a strawberry a berry even while understanding it’s not really a berry. Correctness is important in formal discussions, but we can have fun being intentionally wrong in everyday speech where poetry and history hold more value.
From there one asks, “What is a berry? What about a banana makes it a berry? And what is a strawberry if not a berry?” And so one reads and one learns. “What about a raspberry? What about grapes?” The internet is as forthcoming with answers as one’s brain is with questions.
It’s not wrong at all. If you look up “berry” in the dictionary the first definition will most likely not be the botanical one.
But everything else you described as learning is all about language and the sociology of science, not facts about fruit itself.