No, they wouldn’t. Taxonomic Nomenclature is conservative and “amphibian” is already taken. You might call them “amphibious mammals”, but not “amphibians”. But we already have such mammals and we don’t call them “amphibious mammals”; we just call them all marine mammals.
But wouldn’t there be some amniotes (extinct ones, at least) which are equally close to snakes and to St. Patrick? Presumably, snakes and saints had a common ancestor more recent than the first amniote, and thus, any amniote from before the snake-saint divergence, as well as any of their descendants on other lines, would be equally close to both.
The ancestors shouldn’t be reptiles, right?
So that makes the definition a good one, since it only includes those ‘closer’. If they’re equally close, they’re not reptiles by the definition.
I thought bats were bugs.
Your first link is too dense for me, but the second link doesn’t seem to say what you imply. (The third link doesn’t work as your “placoid scales” link and it’s corrected version still don’t work either.)
From link two:.
Dinosaurs are not lizards, but they are reptiles, and a certain type of dinosaur, the coelurosaurians, developed feathers and were the forerunners of birds.
The most-recent common ancestor of snakes and saints would necessarily be an amniote; earlier terrestrial critters would be non-amniote tetrapods [aka ‘amphibians’]. Those non-terapod amniotes would be more-or-less equidistant from snakes and saints.
Sure it does (from the second link):
My statement, lo these many years ago, was that it is no longer thought that feathers are derived from scales, which is exactly what the above implies (see esp. the bolded sentence).
The third link is now a dead link, but there are plenty of other sites/cites these days which support the idea.
Your second statement does not follow from your first. The most recent common ancestor of snakes and saints would be an amniote, and the first amniote is certainly a common ancestor of snakes and saints, but the first amniote is almost certainly not the most recent common ancestor.
Well, there we get into the differences between node-based, stem-based, and crown-based definitions, which I, as I am just out the door, can’t get into right at the moment…
I’m not a biologist, so take this with a grain of salt. I’ll appreciate it if any biologists correct any mistakes.
Right! There’s a big difference between “closely related” using the term “related” biologically, and “similar” (or using “related” in a generic, nonbiological sense.)
Sharks are morphologically a lot more similar to bony fish than to elephants, but their most recent common ancestor to the elephant is more recent. When ecologies change or populations get divided, evolution can happen rapidly, bringing about remarkable morphological changes in relatively small numbers of generations. That happens a lot more frequently on land than in the sea.
The binomial classification is merely a name registry and, except for the very last (genus/species) division, doesn’t convey much in terms of relationships. This is a good thing, because relationships keep changing as we learn more, and despite all the math and science in cladistics and molecular clocks, there are a lot of cases where the relationships are ambiguous. There’s often more than one way to make a cladograph from the same data set, and different kinds of data often appear to contradict each other, in the details.
To the extent that genes can be transferred by retroviruses, a true objective cladograph can even be impossible. That is, genes can be “inherited” from relatively unrelated species. (Whether this is significant enough to actually affect any classifications is way beyond my ken.)
I disagree that monophyletic clades are the only “valid” or useful groups. It’s handy to have names for sets we discuss, even when they’re not complete monophyletic clades. For example, we often talk about dinosaurs excluding birds. While birds are definitely descended from dinosaurs, it still makes sense to have a term for a group that includes dinosaurs that are not birds. Of course, where to draw the line between dinos and transitional birds becomes a matter of opinion, but that’s true of many questions in classification, even using cladistics.
Does it sometimes cause confusion? Of course. All attempts at systematic nomenclature in any art or science have issues when viewed from a different point of view than the point of view that was central to the system. To handwave all other viewpoints as irrelevant is silly.
Atheists might disagree, since that term is shorthand for “God’s Creatures.” 
Ok, the definition I was using was a crown-based one (“the most recent common ancestor of reptiles and mammals, and all its descendants”). Chronos is usng a node-based definition (defined by the apomorphy of having an amniotic egg). So, from Chronos’ perspective, yes, there would be stem-based amniotes which were neither reptiles nor mammals, and would thus be equidistant from both saints and snakes. Using a crown-based definition, as I was, all amniotes would be closer to saints or snakes. So, my fault for not defining where I was coming from initially.
I dunno, that correlation seems to tip my BS meter slightly into the greenish-yellow zone.
Not that there aren’t some not-so-obvious genetic relationships in the animal kingdom, mind you. One example is that landmark Danish study published last year that found incontrovertible evidence that the Killer Whale (Orcinus orca) is actually a type of chipmunk, specifically a subspecies of the red-tailed chipmunk (Tamias ruficaudus). The study’s research team was exquisitely well-credentialed—one even having a Bachelor of Arts degree in music! And they are well-published in the prissy peer-reviewed scientific community, with most of their papers having to do with the psychotropic effects of Cannabis sativa and its association with appetite enhancement. They’re all pretty fat, but they know what they’re talking about…when they’re not rambling on about minutia. And, if you ever book them for a speaking engagement, ask them to arrive an hour earlier because they drive really slow.
Well, yes, but that’s a wholly separate issue than defining Sauropsida/Reptiles.