There can’t be a definition of reptile that includes lizards, turtles and crocodiles but doesn’t include birds. So yes.
NM
If dinosaurs aren’t reptiles, then crocodiles aren’t either.
It seems to me that if you declare that dinosaurs aren’t reptiles, then there’s no such thing as a reptile. The only way to really preserve “reptile” as anything other than a descriptive term is to make “reptile” synonymous with “sauropsida” , which makes birds and dinosaurs into reptiles, or “amniote”, which would also make mammals into specialized reptiles.
You can’t have a group that includes turtles, lizards, snakes and crocodiles that doesn’t also birds and other kinds of dinosaurs.
In the exact same way that they are also fish. 
Yes. People are fish too on that basis. It’s not surprising that definitions originally formed before the modern level of knowledge are blurry around the edges. Some of these old terms have to be replaced with new ones. Not just in scientific terminology, but colloquial terminology as well.
As Polycarp noted, the term was coined to include to rather disparate groups of what then appeared to be large extinct reptilians. This was unfortunate, as if you lump Saurischians + Ornithischians together, then Aves must be included as part of that clade. Actually, other than Owen making a mistake based upon inadequate info (take at look at some of his “Reconstructions”), there’s no real reason to do so, and he would likely have thrown Ichthyosaurs, Plesiosaurs, etc in there too. This is why we now have to use the term “Non-Avian Dinosaurs”.
It’d be better just to dump the term “Dinosaur” and use Saurischians , Ornithischians, etc.
For a interesting take on aquatic, you have
Hesperornithes - Wikipedia
Yes it is.
No, the inclusion of Aves in Dinosauria isn’t caused by the lumping of Saurischians and Ornithischians into one group named “dinosaurs”. The reason birds are dinosaurs is that Theropods–the meateaters like Allosaurus and Tyrannosaurs–are dinosaurs, and we now know that birds are Theropods.
If you want to argue that “Dinosaur” should be synonymous with “Archosaur”, then fine. But unless you want to argue that Saurischians like a Tyrannosaurus and a Brontosaurus aren’t dinosaurs, you’re not getting away from terms like “non-avian dinosaurs”.
And yes, I was wrong to say that there weren’t any aquatic dinosaurs. There were, but only avian dinosaurs. My main point was to stress that Sauropods were not aquatic as was previously thought, and that ichthyosaurs, pleisiosaurs, and all the various mesozoic marine reptiles weren’t dinosaurs. Even you want to broaden the term dinosaur to make it synonymous with “archosaur” that would only include crocodiles as aquatic dinosaurs, because these other groups weren’t archosaurs.
An old post of mine describing what a dinosaur is:
Well, yes. But lumping together Saurischians and Ornithischians was unessesary and caused by ignorance. They aren’t all that closely related.
Certainly birds and Saurischians are closely related, and birds are likely (but there’s some doubt) descended from Saurischians. That does not mean that they have to be members of the same order.
In fact the divisions and phylogenity are all mixed up:
here we have Theropoda a suborder of the Order Saurischia, and part of the Class Reptilia:
Here we have the Birds and Dinos being part of the Class Aves.
Here’s a list of classes:
So there’s still disagreements over whether Aves is a Class or a even just a branch.
The old system of KPCOFGS is going away fast I know. But still there’s plenty of room to have Aves and Saurischians separate, even if they are fairly closely related or even descended from each other.
How would that work?
It would also be just as possible to consider Pterosaurs to be Dinosaurs, there’s actually no clear solid dividing line. They are both considered to be part of Avemetatarsalia aka Panaves, which would include them in a “super-class” of Aves, Dinos and a few other related beasts.
No there isn’t, at least in any fully modern classification scheme. The ones you quote as being different are out of date.
Alternative theories and controversies
Early disagreements on the origins of birds included whether birds evolved from dinosaurs or more primitive archosaurs. Within the dinosaur camp, there were disagreements as to whether ornithischian or theropod dinosaurs were the more likely ancestors.[18] Although ornithischian (bird-hipped) dinosaurs share the hip structure of modern birds, birds are thought to have originated from the saurischian (lizard-hipped) dinosaurs, and therefore evolved their hip structure independently.[19] In fact, a bird-like hip structure evolved a third time among a peculiar group of theropods known as the Therizinosauridae.
A small minority of researchers, such as paleornithologist Alan Feduccia of the University of North Carolina, challenge the majority view, contending that birds are not dinosaurs, but evolved from early archosaurs like Longisquama.[20][21]
In other words, the common ancestor of both were possibly Archosaurs.
Why not?
Are not the ornithomimosaurs and maniraptors **separate **subgroups of Maniraptoriformes?
At some point, somewhere between Maniraptora and* Ornithurae * (depends on who you agree with) we have a division where modern Birds have split off from their earlier kin. Right? At some point, the modern Birds diverged from the animals most laymen would call “dinosaurs” . It makes not matter what that point is, they COULD draw the line here and call that group dinosaurs and the Modern birds Aves if they like. Sure, birds likely came from Dinosaurs. So, Dinosaurs and Aves and mammals and etc all came from common ancestors of Tetrapods. That does not mean that frogs are Mammals.
Thanks. I though that was what you meant. I was actually pointing at the concept of orders that are “descended from each other”, which seems unlikely.
From what I read it seems that many think that this thing did, in fact, fly.
Yes. “Modern birds” split off from other types of birds within the group Carinatae. Their closest non-modern bird relatives are the Hesperornithes (flightless marine birds). If you draw the line there between “bird” and “dinosaur”, then there are plenty of aquatic and flying dinosaurs, including Enantiornithes (Enantiornithes - Wikipedia). However, most people working on fossil birds place the line to include all of those things despite the fact that they’re only distant relatives of “modern” birds (i.e. the group including only types of bird alive today).
This is nonsensical. Nobody is saying mammals evolved from frogs. They DID ultimately evolve from “fish” and so you would be correct, in modern classification, in saying mammals are fish (unless you restrict “fish” only to ray-finned fish or something). This is trickier though because there is no scientific group called “Fish” (Pisces is not really used anymore BECAUSE it is not a natural group unless it contains tetrapods, and Reptilia is starting to go the same way).
On the other hand, unfortunately, Dinosauria is a scientific group. IMO it would have been much less confusing to relegate the term “dinosaur” to the scrap heap along with Pisces, Thecodontia, etc. when it was found to be non-natural with respect to birds. But people thought “birds are dinosaurs” was catchy so it stuck around.
*Note that the original definition of dinosaur initially also explicitly excluded sauropods, which Owen thought were closer to crocodiles. If we allowed sauropods to be shoehorned in as dinosaurs, in principle there’s no reason birds can’t be shoehorned in wither, though it obviously causes more confusion due to the fact that they’re not extinct.
What about drawing the line at beaks? Were there any creatures that we traditionally think of as “dinosaurs” that sported such a mouth arrangement? Have there been any “birds” after the K-T extinction that carried teeth?