That’s because “fish” isn’t a useful term. You are lumping together bony fishes, jawless fishes, and cartilaginous fishes. Those groups split off from each other millions of years before life reached land. Yes, you and a dolphin and a plesiosaurs and a trex are all more closely related to bony fishes like a carp or salmon than such a fish is to a shark or ray or lamprey.
To get more specific – long, long ago, fish first evolved. One group became the jawless fish, one the bony fish, and one the cartilaginous fish. You also had the armored fish like dunkleosteos and the spiny sharks, but those two flares are totally extinct.
Among the bony fish, you’ve got ray finned and and lobe finned fish, and the lobe finned fish are the ones who would eventually become amphibians. Most lobe finned fish are extinct, with coelacanth being one exception. And yes – a coelacanth is more closely related to you, than it is to a ray finned fish, and WE are more closely related to that ray finned fish than it is to a shark.
Cladistics is about classifying things by their relationship to one another. If you want to use common traits instead – “they both have fins” or “they both fly” – you’re welcome to, but that’s not a scientific approach, any more than “a beaver is a fish because Catholics eat it on friday” is.
In other words – can YOU give us a useful definition of the word “fish” that includes all bony, jawless, and cartilage fish, but not any other animal?
Correction: Most aquatic lobe-finned fish are extinct. But some lobe-finned fish are currently sitting at computer keyboards typing to each other about the oddities of cladistics.
In exactly the same sense that it’s correct to say that a chicken is a dinosaur, it’s also correct to say that a whale is a lobe-finned fish. If “non-avian dinosaur” is not a useful category because it’s not a clade, then neither is “non-terrestrial lobe-finned fish”.
Useful? Of course. Something like (as Wikipedia put it): “Fish are gill-bearing aquatic craniate animals that lack limbs with digits.” A real evolutionary biologist could even define the group
Cladistically, this is a not monophyletic group, but so what? A group definition doesn’t have to be monophyletic to be useful. “Domesticated animals” and “edible plants” aren’t monophyletic groups either, but they’re darned useful classifications.
Those are useful categories from the point of view of trying to figure out, “can I keep this animal in an aquarium?” Or “am I likely to enjoy eating this animal?” Or “my nephew says he likes dinosaurs, what kind of you should I buy for him?”.
They are not useful when we are trying to figure out where on the tree of life a creature belongs.
Also, I think that non avian dinosaur IS a useful term. We all know what it describes – dinosaurs who lack avian properties. However, many animals that went extinct 65 million years ago, had teeth, and to you or I would look like a dinosaur, are NOT non-avian, because that line is very blurry. And while we don’t share many traits with the coelacanth, birds very much share many traits with dinosaurs, while dinosaurs (such as Stegosaurus) share very few traits with other dinosaurs (such as velociraptor). So you could make the argument that while cladistically humans are lobe finned fish, their traits separate them sufficiently from fish that calling a human a fish in everyday usage is ridiculous. After all, there are traits that all mammals share that fish lack.
What trait do all birds share that non avian dinosaurs universally lack?
“lobe-finned fish” is a clade, though (one that includes us tetrapods), and “fish” is not. So you can correctly say we’re lobe-finned fishes, but we’re not fish. Silly as that sounds.
I don’t see why that’s “silly”.
Not a Dinosaur
Godzilla
Anguirus
Rodan
Rhedosaurus (the thing from Beast from 20,000 Fathoms)
Whatever the hell that thing Ringo Starr was riding in Caveman)
Everything in the movie When Dinosaurs Ruled the Earth, ironically
Everything except the T. Rex in the Land Unknown (although the head later showed up as “Spot” on The Munsters)
The Dimetrodons in journey to the Center of the Earth (1960)
The creatures in Jules Verne’s original novel A Journey to the Center of the Earth (1864)
The creatures in Edgar Rice Burroughs’ *Pellucidar * series (although burroughs does get credit for dinosaurs in his Pal-ul-don and Caspak series)
“Dinosaurs” on alien planets. I don’t care how much they may look like them, they have a different ancestry.
Dragons
Sirrush (probably)
Mkele-Mbembe, whatever they are, more than likely. I don’t care what Disney says.
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Had to check.
The first modern, commercially available toilet paper came on the market in 1857. And although microscopes were available a good bit before then, they probably weren’t considered for use in paleontology until much later. So that checks out.
The Bone Wars didn’t start until 1877, though, so in theory the bone warriors had toilet paper.
“We’re […] fish, but we’re not fish” doesn’t strike you as oxymoronic?
It does strike me as silly if you intentionally leave out some word, yes.
Lobe Finned Fish is the name of a class that contains the earliest lobe finned fish and all of its defendants, which include all lobe finned fish, as well as all land animals. You could replace that word with one that doesn’t carry this baggage:
We’re Sarcopterygii but we’re not fish (an arbitrary category that includes all sorts of different aquatic gilled animals, unless their lobed fins are too well developed)
We’re selfish but we’re not shellfish!
We’re […]fish but We’re not […]fish? Ridiculous!
The crux of the matter is, “Do all dinosaurs taste like chicken?”
Humour. It is a difficult concept.
Look, when I said it sounded silly, I wasn’t making a statement about the science of it. I literally meant that the English sentence I typed was, itself, silly-sounding because it sounded like it was internally contradictory. I was not saying it was an oxymoron, just that the phrasing sounded that way.
Does duck? Does ostrich?
The answer to that is “no, it tastes like oranges”, and “no, it tastes like venison”, respectively.
I expect T-Rex to taste of a fine port wine reduction. Or at least, by the time I’m done…
Well, turkeys don’t. Therefore, no.
Does the final statement in this dialogue sound silly?
A: Look, a red breasted parrot!
B: Oh, that’s a pretty parrot.
A: (sternly) It’s not a parrot. It’s a red breasted parrot.
Same thing with “we’re lobe finned fishes” but “we’re not fishes”. Normally in English when you modify a noun with an adjective, you get a description of a thing that belongs to a subset of the set described by the noun.