Well, except that things like Flight have shown up over and over- bats, birds, reptiles, insects, etc.
interesting thingy: boffins manipulated chickens’ genomes (I think they got one specific gene that was already there to be expressed), and got chicks in eggs that grew teeth
Thing is, the classic “fish, amphibian, reptile, mammal, bird” classes don’t line up with reality.
Some trees put synapsids–the base group that includes modern mammals–as more closely related to diapsids (lizards|snakes|crocodiles|dinosaurs|birds) than those groups are related to turtles (anapsids). This would make mammals into reptiles, if we wanted to bother keeping the term reptile as a phylogenetic name rather than a descriptive term.
But almost all modern trees put turtles as more closely related to the above group than they are to synapsids, this tree shows this theory: https://dr282zn36sxxg.cloudfront.net/datastreams/f-d%3Ab0005720d771053de01f08262d4f22707cd194e68b3854b0504cdc34%2BIMAGE_THUMB_POSTCARD%2BIMAGE_THUMB_POSTCARD.1
Which means reptiles can be kept as long as we’re willing to call birds a specialized type of reptile. If you don’t want to call birds reptiles, then we have to get rid of the idea of reptile.
A better term than “reptile” would be “Amniotes”, which includes mammals, mammal-like reptiles, reptiles, birds, and so on, but not amphibians. “Tetrapods” would include the various types of amphibians but not fish. Here’s a tree that presents this view: http://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/Vertebrata_cladogram2.png. Notice some fudging–some of these branches are three pronged rather than two pronged.
The point is, words mean whatever we agree that they mean, and they can mean different things in different contexts. I wouldn’t be confused if someone showed me a bone from their backyard and said “This isn’t a reptile bone, it’s a bird bone”, despite the fact that I know birds are a kind of reptile. The only time I might be confused is if it was a Jurassic or Cretaceous fossil, then we’d have to agree on what we mean when we use the words “bird” and “reptile”.
I classify animals in order of cuteness
At the top of the list is bunnies
followed by dogs, cats, bears, porcupines, wombats and so on. The least cute are on the bottom
It’s a much more useful taxonomy
As long as one doesn’t mix up the difference between a genealogical ancestor and a genetic ancestor, it’s strictly a (pedantic 
) usage difference. However, when one is talking about the ancestor of more than one species, LCA is preferred to help make this distinction.
From Wikipedia,e.g.:
*“It is also possible to use the term MRCA to describe the common ancestor of two or more different species. In the past, the term MRCA was used interchangeably with last common ancestor (LCA) to denote both the common ancestor within a species and that between species. But MRCA is now more frequently used to describe common ancestors within a species. On the other hand, LCA now describes the common ancestor between two species.” *
I sort of think of the LCA as the anchor point from which SNP variations drove the assortment of descended species.
I’ve seen discussions elsewhere on the SDMB where people get confused about the term MRCA and make an assumption it implies the MRCA is the source of the descendants’ ancestral genes…
Toothlessness also shows up multiple times - in birds, in Quetzalcoatlus and Pteranodon pterosaurs, turtles… Some non-avian dinosaurs like ceratopsians, and some theraspid proto-mammals like Diictodon were part-way there, too.
I saw what you did there, you retro sweetie, you. 
Terms that describe the body plan and function of organisms are not what interest cladists, but not interesting cladists is a far different think than being useless.
No - in cladistics, “fish” is simply not a valid clade, being paraphyletic.
Maybe, but can we still be rodents?
It’s a bird! It’s a plane! It’s Superprimate!
We’ve never been rodents. And I think you mean “Supraprimate!”
Unless I’m missing something, true flight has evolved three separate times: insects, dinosaurs (obviously inclusive of birds), and bats. Flying fish don’t fly, but glide, and spiders balloon.
Pterosaurs aren’t dinosaurs, and evolved flight separately from them. So that’s 4.
Interesting.
For a certain definition of “dinosaur”. phylogenetic taxonomy.
Let face it Sir Richard Owen screwed up when he lumped Ornithischia and Saurischia. Nor are dinosaurs "lizards’, nor are they all huge.
He was operating on inadequate info.
If he hadnt made that mistake we wouldnt have to use the awkward phrase “non avian dinosaur” nor would we have to put up with pedantic assholes who will always point out that “birds are dinosaurs”.
What possible way could you monophyleticly define dinosaurs that does not include birds? (Says a proudly pedantic asshole)
You dont. You dont give a fuck for phylogenetic taxonomy. You go by Linnean definitions and by common usage.
They why use that new-fangled Linnean system? Why not describe animals the way they were defined by Aristotle, or Leviticus?
Linnaean classification is gradistic, rather than cladistic. As such, it paid little attention to the phylogenetics of any group, and simply classified animals based on relative degrees of “sameness”.
Linnaeus is dead. His classification scheme ought to be, as well.
And “common usage” is a non-starter, since the whole idea of binomial nomenclature in the first place was to get away from having a dozen “common names” for every living thing. Common usage also tells us literally nothing about the relationships between organisms.
Info which has, on numerous occasions since, been corroborated; Dinosauria is confirmed to be a monophyletic clade. Owen did make a lot of mistakes, but that wasn’t one.