Other than the plated scales, tough leathery skin, frilled head, horned skull anatomy and sinuous tail, mythological and folkloric dragons have very little in common anatomically with actual reptiles. They have MORE in common with the Felidae genus (cat family) and the Aves Phylum Chordata (bird classification).
Like a cat’s eye, a dragon’s eye has a comparatively large iris with a vertical pupil. This arrangement allows the pupil to open extremely wide and receive
more light than that of a human eye.
A dragon’s legs are also decidedly nonreptilian, despite the scaly coverings. A dragon’s legs are positioned more or less directly under its body, in the manner of mammals. (Most reptiles’ legs tend to splay out to the sides, offering
much less support and mobility than a mammal).
Lasly, a dragon’s four feet very closely resemble those of a great bird. Each foot has three or four clawed toes facing forward (the number varies, even among dragons of the same kind), plus an additional toe, also with a claw, set farther back on the foot and facing slightly inward toward the dragon’s body, like a human’s thumb.
A dragon’s resemblance to a reptile is literally only skin deep So the next time someone you know refers to mythical dragons as giant lizards, you’ll have the know-what to save a life.
So I have issues with this post, and mostly have been ignoring it, but it’s appeared on my dash enough for me to want to address it. Surprisingly enough, most of my issues aren’t because this post seems anti-Reptilian Dragon, but rather that the information you’re using to support this belief is inaccurate.
First some nitpicking. Felidae isn’t a Genus, and Aves isn’t a phylum. Already we’re off to a bad start.
So you first say that dragons, like cats, have slit pupils. Not wrong, but not right either. Here are some other things with slit pupils:
And here are some things without slit pupils:
Despite what people seem to believe, only small cats have slit pupils. Slit pupils are a small cat trait, not a cat in general trait.
Next you mention how dragon legs are positioned under their body, like those of a mammal rather than a reptile. Except there have been reptiles with legs positioned under their bodies. Dinosaurs are one, and some extinct crocodile relatives are another.
Now, this would be the point where you tell me that dinosaurs aren’t reptiles, instead being related to birds, and this would be the point where I tell you that you’re both right and wrong, because reptiles don’t actually exist.
As far as actual phylogeny is concerned “reptile” is more or less meaningless. It doesn’t actually define how things are related to each other. Crocodiles, a reptile, are more closely related to birds than they are to snakes and lizards. So there’s two possible solutions to the reptile dilemna:
1) Make is a synonym for all Sauropsids, in which case Dinosaurs, including birds are reptiles or
2) Have it be a vulgar, nontechnical term for creatures which posses any number of arbitrary characteristics, including scales, certain physiological and anatomical features, and which often lay eggs. In which case, a dragon bearing a superficial resemblance to a reptile would be enough to make it a reptile, since ‘Reptile’ is essentially meaningless.
It’s also important to note that actual reptiles can have very little in common in terms of anatomy, past some bare bones aspects. Crocodilians have internal anatomy closer to birds than other reptiles, and even monitor lizards have a very complex respiratory system. Even the whole Warm vs Cold Blooded thing isn’t accurate, since real animals usually have much more complicated systems for maintaining body heat than that dichotomy.
You also mention how dragon feet are closer to bird feet. I would argue that, since dragons are usually shown with pronated hands, they can’t be related to birds, since no dinosaurs had pronated hands. I would also suggest you take a closer look at some reptile hands, they can be quite interesting.
And finally, my biggest issue. Dragons are not homogeneous in design, anatomy, or style. The kind you show are the most recent D&D designs, which yes, you could argue they take more inspiration from dinosaurs, felines, and avians than modern reptiles, but that is only one style, from one work. In terms of design, there’s no such thing as “mythological and folkloric dragons.” In Ancient Greece alone, we had giant snakes, giants essentially made out of snakes, and a three headed hound covered in snakes. France has a dragon that’s a snail. China has a dragon that’s a fish. The Grootslang is part elephant. Dragons, even when they aren’t reptilian, are wildly more diverse than just being cat-birds.
TL;DR: If you want bird/feline dragons that’s fine, but this post uses false information to support its point.