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Re: Yet more reptile stuff (long)
Thomas R. Holtz, Jr. wrote:
> At 12:00 AM 12/18/98 -0600, Chris Campbell wrote:
> >> But there are a lot of derived features unique to turtles PLUS lepidosaurs
> >> PLUS archosaurs.
> >Beyond skeletal features? Like what?
> Uricotely: the ability to eliminate wastes as uric acid (saving water)
> rather than as urea.
> Four or more type of color receptors in the eye, giving greater potential
> for color acuity.
Is this unique to reptiles? Seems to be fairly common among mammals as
well, at least to some extent.
> A unique system of striated ciliary muscles in the eye that inserts on the
> lens in an equatorial ring for rapid focusing.
> A fully developed and highly mobile nictating membrane.
Is this also unique to reptiles? I know lots of other animals have
this, particularly sharks; convergence?
> Specialized keratinized scales (using different keratins than fish and so
Are the scales in turtles and birds really that comparable?
> Great reduction in the number of glands in their skin.
Compared with what? Fish?
> Among others: people more familiar with modern reptilian physiology can add
I'd like to know these, particularly some which are easily observed.
> >Of course there is, I know that. I suffered through CVA just like the
> >rest of you. That doesn't change the fact that "reptile" has lots of
> >different meanings, creates confusion in folks who aren't taxonomists,
> >and carries with it heavy implications in terms of biology and
> Okay, I DO agree that "Reptilia" comes with a lot of non-scientific baggage,
> and all in all I would have liked to see a different name used. However,
> that was the term that was used, with an explicit definition, and by the
> principles I work under that is necessary and sufficient to use it.
I can see how it would be, but still think someone oughtta go about
> And anyway, folks who aren't taxonomists tend to think "animals" just means
> "mammals" anyway. That doesn't mean that we should stop using Animalia.
What folks are these? People I've talked to always include birds and
reptiles and fish in that equation, and usually amphibians as well.They
don't think of rotifers or worms or even insects, really, but they do
think of big, non-human, non-plant living stuff.
> >It's not the same as, say, "diapsida" since diapsid refers to
> >one thing and one thing only -- holes in the skull.
> No, it doesn't refer to one thing and one thing only. It refers to a
> pattern of common ancestry, and in fact has always done so. In fact, since
> that's terms inception, it has been recognized that the VAST majority of
> species in Diapsida lack a typical diapsid skull condition. Squamates
> (lizards and snakes) and birds have long been a part of Diapsida, but both
> have lost one of the two openings. Textbooks refer to this as a "modified
> diapsid condition" (yes, so modified that it isn't justified calling it
> "di-"...). The concept of common ancestry has been in play since the
> beginning: squamates and birds were considered diapsids, even if they had
> lost the eponymous condition.
Nonetheless, you're talking about a history based on that skull
condition. I haven't gotten too too much into cladistics, but my
understanding is that there aren't many other traits associated with
diapsids (used as part of the definition, anyway) beyond that skull
condition or membership in a lineage that once had it.
> >Now, I know you don't include these things in
> >your definition, and that's fine, but that's what the definition means
> >to a lot of people. You're redefining the word, which is fine for
> >cladists, but who's gonna catch up the rest of the world?
> That's what education, including a forum like this, is about.
It can only go so far, though. Telling us dinos weren't big, sluggish,
stupid animals is one thing; movies, books, and popular articles can
accomplish that. Telling folks they need to think about reptiles based
on skeletal features and a host of minor yet significant biological
traits is a whole different ball of wax.
> >> What is it you want it tell us? No, really, I am intrigued by this
> >> question. You (and you are not the only one this list: the same questions
> >> rise up every six to nine months, it seems) seem to be expecting something
> >> from taxonomy other than labelling particular branches of the tree of life.
> >I want it to tell us something readily observable about the animals in
> >question. Mammal tells me an animal bears and nurses live young and
> >that it has hair of some sort.
> Please don't leave the monotremes out in the cold: they are nursed, but they
> aren't "born live" as the phrase goes. (The writer of Science Made Stupid
> points out that animals whose young are born dead aren't going to leave a
> lot of descendants...).
That's a derived trait, though. But, fine; chop off the "bears".
> >Reptile, particularly the cladistic
> >definition, tells me nothing whatsoever about the animal in question.
> >It doesn't tell me what it looks like, how it acts,
> And "fish" does? Please check up on fish diversity some time.
Sure "fish" does. It tells me the animal has fins of some sort and
> >how it's covered,
> No, that it does, even down to the protiens used.
Okay, fair enough.
> >how it moves,
> This is different from "Mammalia" how? Mammals have quadrupedal walkers,
> bounders, and runners; fliers and gliders; arbors and fossors; bipedal
> stripers and jumpers; and swimmers of all sorts. Reptilia has quadurpedal
> walkers, bounders, and runners; fliers and gliders; arbors and fossors;
> bipedal striders and jumpers; swimmers of all sorts; and legless slitherers
> to boot. With the exception of the addition of the snake body plan, how is
> this different?
I don't expect a definition to necessarily explain how an animal moves;
that wasn't what I was getting at. My point was that "reptile" doesn't
tell us this in addition to a lot of other things, some of which are
covered by other definitions. Now, the keratinized scales is a good
one, but I don't think it's enough by itself for common usage purposes.
Other general terms such as fish, amphibion, or bird tell us more about
the animals than just their covering.
> >I don't expect a definition to tell me all of the above, but I expect
> >*something* to go on, particularly if it's a definition in common use
> >not only in the biological sciences but in the world at large.
> Again, there is a vast world of difference between the common use of the
> term "animal" and the scientific use of the word "animal".
It's mainly one of scope, not concept. Scientists include many other
critters in the term, but they don't use it in a completely different
fashion, to apply to completely different sets of characteristics. The
common and scientific uses of "animal" are not at odds, in my
experience; the common and cladistic uses of "reptile" are.
> >What I suggested forces a focus on groups sharing readily observable
> >common characteristics. Turtles have that big ol' shell, birds have
> >feathers and kick-ass homeothermy, crocs have dermal armor and a divided
> >circulatory system, and lepidosaurs have that cool motion that scoffs at
> >so-called better ways of getting about (among other things, of course).
> >"Reptilia" lets a reader stop right there without considering just how
> >different these groups are.
> Only if they chose to go no deeper.
It's not a matter of what they choose. If you use "reptile" in an
article they'll think of what they commonly associate with "reptile",
i.e. cold-blooded, scaly, whatever. If you use "squamates" (and define
it, since they won't know what you're talking about at first) or
"testudines" or "archosaurs and their descendents" the reader has a
specific idea of what you're talking about and is focusing on the
animals in questions rather than some vague, baggage-laden term.
> >> Amniota is the "main" (or at least most inclusive) group. Synapsida and
> >> Sauropsida are the two main divisions within it. Within Sauropsida we have
> >> Mesosauria and Reptilia; within Reptilia with have Anapsida and Diapsida;
> >> within Diapsida we have Lepidosauromorpha and Archosauromorpha and
> >> Euryapsida (which might belong in one or the other, who can tell).
> >Which is great for cladists. The rest of us aren't in the same boat.
> Then time to play catch up. Sorry about this, but if you want to get into
> scientific disucssions, you have to learn how the terms are used, even if
> they might be the same as commonly used words.
I know the terms used (or have easy access to glossaries telling me what
they are). That's not the issue. The issue for me is what the term
means and how it's used by people outside of the realm of cladistics,
and whether or not it has value for science as a whole given what it
means to those people. In my opinion we'd be better off without it. In
essence, I've changed my argument on you: I recognize the utility of
grouping turtles, squamates, and archosaurs together, but dislike the
use of "reptilia" as a label for that grouping, mostly due to the fact
that it doesn't mean the same thing to most folks as it does to you.
You can say "time to play catch up", but you're gonna have to explain to
them, in terms they can recognize, why they should bother. Maybe that
can be done, maybe it can't, but I haven't seen it done here.
>After all, the physicists use of the common words momentum, mass, weight,
>inertia, chaos, acceleration, and so forth are often very different from
>the use us ordinary folks use.
Maybe it's just my background in physics (which isn't much, being a
class shy of a minor as an undergrad), but I've always found that
momentum, mass, weight, inertia, and acceleration have been used in the
same ways by both normal folks and physicists. Force is mangled a lot,
but that's just because it means so many different things in so many
different contexts. Chaos is used in pretty much the same way, even
though most folks don't get Chaos Theory.
> >> As a loyal Terrapin, I find your comments bigoted and outragous. Turtle
> >> Power!! :-)
> >I'm *trying* to empower them, but you just wanna demote them to the rank
> >of common reptile!
> *BING*!!! I thought that might be at the heart of this. "Rank". Ugh.
Well, that's one way of looking at it. It's always better to stand out
than be part of the crowd, IMO.