1211: "Birds and Dinosaurs"

This forum is for the individual discussion thread that goes with each new comic.

Moderators: Moderators General, Prelates, Magistrates

User avatar
Eebster the Great
Posts: 3484
Joined: Mon Nov 10, 2008 12:58 am UTC
Location: Cleveland, Ohio

Re: 1211: "Birds and Dinosaurs"

Postby Eebster the Great » Wed May 15, 2013 12:58 am UTC

tofudragon7 wrote:When you add in the fact that the T. rex - bird split contains more (and slightly more significant) extinction events and thus likely more adaptive radiation, Tyrannosaurus is almost certainly more similar to Stegosaurus than to birds!

Your theorycrafting won't convince me as much as actual fossil evidence. The fact of the matter is that morphologically, birds and T. rex are much more similar than T. rex and Stegosaurus.

Pfhorrest wrote:I'm arguing the same with regards to "dinosaurs". That's a word already in common usage to describe a group of animals which, as it turns out, is paraphyletic, because birds share the same common ancestor but aren't counted in it. Rather than redefining the common word to mean something no non-specialist would use it to mean, why can't we come up with a new technical term (like "avesaurs") for the monophyletic group, like we have "sauropsida" for the group containing all modern reptiles and birds?

But "dinosaur" is a technical term, just one that has now entered into common vocabulary. Dinosaurs are the clade consisting of Triceratops, birds, their MRCA, and all its descendents. What you are proposing is actually redefining the word to accommodate general ignorance.

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 26822
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby gmalivuk » Wed May 15, 2013 1:25 am UTC

No, the word "dinosaur" originated amid general ignorance, and then *scientists* changed how it was used to accommodate new information.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

User avatar
Eebster the Great
Posts: 3484
Joined: Mon Nov 10, 2008 12:58 am UTC
Location: Cleveland, Ohio

Re: 1211: "Birds and Dinosaurs"

Postby Eebster the Great » Wed May 15, 2013 1:32 am UTC

gmalivuk wrote:No, the word "dinosaur" originated amid general ignorance, and then *scientists* changed how it was used to accommodate new information.

I didn't say anything about how the word originated, merely how it is currently used (and has been used for decades).

User avatar
tigerhawkvok
Posts: 18
Joined: Mon Jan 21, 2008 8:51 pm UTC
Location: Berkeley, CA
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby tigerhawkvok » Wed May 15, 2013 1:32 am UTC

Pfhorrest wrote:
tigerhawkvok wrote:Why in the world would they need to be abolished? There are easy fixes. "Reptile" = "Sauropsida". Blam-o.

So birds are reptiles now, not merely dinosaurs? Are they going to be called fish next?

Of course they're reptiles. Not calling them such has always been dicey. They lay eggs and have scales in the lay-superficial-feature world, and we don't not call facultatively ectothermic sloths mammals, nor do we not call the egg-laying monotremes mammals, nor do we exclude furless cetaceans.

On sloths:
ROBIN A. COSTELLO AND JESSE T. RIEB wrote:Sloths’ thermoregulatory strategy, which can be described as facultative poikilothermy, could account for further reductions in metabolic rate. Unlike most mammals, the body temperature of a sloth can vary by as much as 10°C (Kredel 1928). Through facultative poikilothermy, sloths have evolved a lower lower critical temperature (LCT), the point below which an endotherm must increase their metabolic rate to thermoregulate. (Source: MEMBERS OF THE DARTMOUTH BIOLOGY FSP2012)


Here, let's make a list. Birds share the following with "lay-reptile":
1) Scales
2) Egg laying

Birds *don't* share the following with "lay-reptile":
1) Feathers (novel feature!)
2) Endothermy (mind, some pythons can be facultatively endothermic, so I think even this is dicey, but I'll leave it here to be as fair as possible)

Remember crocs share an ancestral and currently facultative upright gait, and croc hearts have the crazy shunting mechanisms that prevent that from being used as a criterion, unless you're claiming crocs aren't reptiles.

Now, whales share the following with other mammals:
1) Live birth
2) Milk

Whales *don't* share:
1) Dorsal fins
2) The melon (novel feature!)

I'll leave fur off the list as some whales have small bristles (again, to be as fair as possible).

Why, then, are whales mammals and birds not reptiles? Note I'm not even touching prototherians here.

Why do we need to redefine the word "reptile" to mean something no non-specialist uses it to mean, when there is already a perfectly good word ("sauropsid") for specialists to use for that purpose?

I'm arguing the same with regards to "dinosaurs". That's a word already in common usage to describe a group of animals which, as it turns out, is paraphyletic, because birds share the same common ancestor but aren't counted in it. Rather than redefining the common word to mean something no non-specialist would use it to mean, why can't we come up with a new technical term (like "avesaurs") for the monophyletic group, like we have "sauropsida" for the group containing all modern reptiles and birds?

And what, praytell, do we do if it is decided that deinonychosauria is an atavistic avilan branch? Humor the argument and assume it's true. Do you really expect them to be not called dinosaurs anymore? The transition is so fuzzy I'd be shocked if something isn't accidentally misclassified already. People will be resistant to change in either case.
Similarly, it seems everyone is happy to agree that we shouldn't redefine "fish" in a way that would count all vertebrates as fish. But why not? By your line of reasoning shouldn't we?

If a lungfish is a fish, I'm perfectly happy in my fishyhood. That said, the paleobiologists I know refer to fish in a similar way to myself, and texts such a Benton 2005 (ISBN 0-632-05637-1) explicitly mention that tetrapods are in the clade sarcopterygii, and use "fishes" in quotes and explicitly state the paraphyletic usage in the text, but (2) even that is in the sections talking about pre-Devonian animals. In post-Devonian sections, "fish" chapters ignore sarcopterygians altogether.

Talking about "Devonian fishes" and including sarcopterygia isn't paraphyletic, because you're not excluding anything. Get later than that, and you're not only paraphyletic, but much like birds, you have this whole fuzzy zone of "is it/isn't it?" that is a headache and a half. The paraphyly doesn't just fail to illuminate, it brings *new* problems.

Mind, I don't really think selective definitions based on the temporal range is particularly elegant, but at least you don't strand critters in no-man's-land where you have nothing at all to say about them (which is unresolvable when you're paraphyletic unless you're naming every individual animal that lived in those lineages occupying those gnarly transitional zones). 99% of the renaming people wouldn't even notice, anyway. How many people know what a coelacanth is? I've even gotten blank stares about "lungfish". I hardly see the problem in excluding sarcopterygia from fishes.

The Cat

Re: 1211: "Birds and Dinosaurs"

Postby The Cat » Wed May 15, 2013 1:46 am UTC

I'm leaving the fish/shark/lamprey argument alone here, because it seems like everyone on this board got a different education on the matter from everyone else, though I daresay that actinopterygia=fish, chondrichthyes="sharks, skates, rays" (because lay people don't really group them anyway), and agnatha="who talks about something without a bloody *jaw* as a fish anyway!?!" is good enough.


Word.

http://www.youtube.com/watch?v=2WNrx2jq184

User avatar
Copper Bezel
Posts: 2426
Joined: Wed Oct 12, 2011 6:35 am UTC
Location: Web exclusive!

Re: 1211: "Birds and Dinosaurs"

Postby Copper Bezel » Wed May 15, 2013 1:56 am UTC

tigerhawkvok wrote:Relatedness in biology is based on "shared derived characteristics" (changes), or "synapomorphies". During that period from 230mya -> 150ish mya, the saurischian/theropod lineage accumulated a bunch of changes that *all of them share* that were never accumulated in the ornithischian lineage.

The temporal problem becomes clear when you realize that the distance from us to Compsognathus (us->basal amniotes = +340 MY, basal amniote -> Chasmatosuchus, basal psuedosuchian = +90 MY = ~430 MY) is about the same temporal distance from us to Dimetrodon, also a synapsid like us ( ~ 380 MY temporal distance), which is clearly false. You can artificially inflate this by picking an even more basal sauropsid -- such as https://en.wikipedia.org/wiki/Paleothyris , which has a temporal distance from us of about 370 MY. Is it actually closer to us than we are to Dimetrodon? Of course not.


Wait a second - I didn't realize what tofudragon7 was doing there. So instead of just using the time to the MRCA, ze's adding the the branches going both ways?

I actually think either of those approaches makes a kind of sense; since Dimetrodon had more time to diverge from the basal amniote ancestor than Paleothyris did, which might say something about similarity, but maybe not "relatedness." I take "relatedness" to refer to the MRCA only - I force myself to read "closely related" as "recently related," since "closely related" can be misread in exactly this way.

It's interesting to me, though; I'd seriously never thought of parsing that term that way, and the time levels do have a meaningful effect. A person is more closely related to a grandfather than to an aunt, right? (Not a perfect analogy, since the relatedness meant and the source of new genetic information are different, but they're both still there.)

Also, the synapomorphies that you refer to as defining relatedness are shared morphological traits, not shared genetic traits. Molecular relatedness doesn't care how much a lineage changes on the outside. So I'm not sure that the synapomorphies that define the saurischian line, as you say, are the only important consideration here.
So much depends upon a red wheel barrow (>= XXII) but it is not going to be installed.

she / her / her

User avatar
tigerhawkvok
Posts: 18
Joined: Mon Jan 21, 2008 8:51 pm UTC
Location: Berkeley, CA
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby tigerhawkvok » Wed May 15, 2013 2:19 am UTC

Copper Bezel wrote:Also, the synapomorphies that you refer to as defining relatedness are shared morphological traits, not shared genetic traits. Molecular relatedness doesn't care how much a lineage changes on the outside. So I'm not sure that the synapomorphies that define the saurischian line, as you say, are the only important consideration here.

True, I kind of glossed over that point, though the two do have some kind of mapping onto each other. Busting out trusty old Benton, though, we have birds sharing with _T. rex_ that it doesn't share with _Stegosaurus_:
Lacrimal exposed on dorsal skull roof, cervicals 3-6 longer than axis, accessor vertebral articulations, hand more than 45% of humerus+radius, first phalanx of thumb longer than metacarpal 1, hand digits 1+2 reduced to 2 and 1 phalanges respectively [...] anterior tympanic recess in braincase, 4-branched palatine bone, additional articulation in middle of lower jaw, pluerocoels in cervicals, tibia bears a ridge at the proximal end for contact with the fibular, metatarsal 1 reduced and attached to metatarsal 2 and does not reach the ankle joint proximally, [...] lesser trochanter in femur broadened and wing like, distal end of femur well-rounded, [...] maxillary fenestra in antorbital fossa, lesser trochanter proximally placed but lower than greater trochanter, sharp ridge on tibia for close attachment to fibular offset from proximal end, maxillary antorbital fenestra more than 40% the length of the external antorbital fenestra, feathers, upper temporal fenestra confluent over the parietals and parietals form a sagittal crest, fewer than 41 caudals, medial side of metacarpal 2 straight and without proximal expansion, femoral head separated from the greater trochanter by a cleft, lesser trochanter as high or higher than greater trochanter.

And I left out a bunch in *the list I have* because I didn't want to type it all. I'm sure it's more complete than that. (This is the list of synapomorphies to maniraptorformes. Tyrannosauridae is an outgroup to maniraptora proper)

The Cat

Re: 1211: "Birds and Dinosaurs"

Postby The Cat » Wed May 15, 2013 2:50 am UTC

https://en.wikipedia.org/wiki/Convergent_evolution

____

It's cull, not thin...nature doesn't need any help.

User avatar
Moose Anus
Posts: 443
Joined: Fri Oct 14, 2011 10:12 pm UTC

Re: 1211: "Birds and Dinosaurs"

Postby Moose Anus » Wed May 15, 2013 2:53 am UTC

Himself wrote:I've thought it was interesting that when it comes to mythological creatures, reptilian creatures, mostly dragons, are depicted with bath wings even though bats are mammals while mammals (e.g. Pegasus) are given bird wings, even though birds are more closely related to modern reptiles.

Horsefeathers!

Image
Lemonade? ...Aww, ok.

EgregiousCharles
Posts: 2
Joined: Wed May 15, 2013 2:51 am UTC

Re: 1211: "Birds and Dinosaurs"

Postby EgregiousCharles » Wed May 15, 2013 4:27 am UTC

The problem in this discussion is that you have people in certain scientific disciplines taking their quite new jargon usage of very old commonly used English words and insisting that all other uses are incorrect, which is crap. It has all the validity of astrophysicists telling chemists that carbon is a metal and they'd better revise the periodic table to reflect it, or computer programmers telling everyone else that it isn't really a kilometer unless it's 1024 meters. Saying lungfish, lobe-finned fish, dogfish, ratfish, and hagfish aren't fish in English, is crap; and likewise saying, for example, John A. Long's "The Rise of Fishes: 500 Million Years of Evolution" is primarily not about fish (because most of it is about other animals like heterostracans, osteostracans, placoderms, chondrychthians, acanthodians, sarcopterigians, etc.) is even more crap. Use whatever jargon you like inside your field; actinopterigiian is a lot longer than fish, and I can see why you want a short form. But don't try to insist that your very new and spectacularly different usage of a word is the correct one; you are not in any way trying to correct a misuse of the original definition, you are trying to substitute a new and completely different definition. And, the instances where the old overlaps with the new is the only reason to try to coopt the old word in the first place. The English word fish has included sharks for a thousand years at least and no one would even try to use it for actinopterigii if it wasn't for all the gar and trout it meant likewise.

In that vein, to say humans are apes or monkeys is incorrect English, though they are homonidea and primates. It is a jargon usage of the word apes and monkeys that is as incorrect in normal usage as saying air is almost entirely metal.
To say humans (and birds and other dinosaurs) are fish is incorrect English, not because they are not actinopterigii, but because they are not fish. Though they are sarcopterigians, and osteichthians, and agnathans - those terms are specific to your field, and if you want to use latinate constructions of "lobe-finned", "bony fish", and "jawless ones" in that sense, knock yourself out. Likewise "Birds are dinosaurs" is fair enough, since "dinosaur" is a technical term vaguely coopted by the populace in inconsistent ways in the first place.

P.S Pine nuts, peanuts, and walnuts are all nuts, though they are spectacularly unrelated phylogenetically. You can substitute peanuts or walnuts in for pine nuts in pesto much more easily than you could lima beans or acorns. In fact, I think I'll lead a revolution to restore tomatoes, zucchini and mushrooms etc. to being vegetables, and strawberries etc. to being fruit.

chenille
Posts: 430
Joined: Tue Dec 20, 2011 7:25 pm UTC

Re: 1211: "Birds and Dinosaurs"

Postby chenille » Wed May 15, 2013 5:23 am UTC

tigerhawkvok wrote:Of course they're reptiles. Not calling them such has always been dicey.

If birds were obviously reptiles from general similarity, you would have expected them to have been called so a long time ago. Instead, biologists considered them separately for several hundred years, even after Huxley proposed birds evolved from reptiles, even after their physiology was better understood; in many circles they still are. It seems dicey now because you're insisting on seeing everything in terms of evolutionary pathways and specific traits that concern them; open any biology textbook from more than a decade or two ago, and you'll see that hasn't always been the perspective at all.

tigerhawkvok wrote:99% of the renaming people wouldn't even notice, anyway. How many people know what a coelacanth is? I've even gotten blank stares about "lungfish". I hardly see the problem in excluding sarcopterygia from fishes.

Most people I know have heard of coelocanths (and lungfish), and definitely consider them fish; that's how the fishermen who discovered and ichthyologists who characterized them thought of them, and that's how they show up in most books and documentaries. And if you're interested in structure, biomechanics, chemistry, neurology, or ecology, it doesn't make much sense not to call them fish, because they are only separated by a few peculiarities like odd fins. The only perspective where they're completely different is phylogenetics.

And seriously, sharks and rays are called fish all the time. I'll believe that's not your personal experience, especially seeing as how you don't seem to talk to many people about fish. But it's not simply my education where they were called such: try looking up the largest fish, search for the terms "cartilaginous fish" and "jawless fish" anywhere you like, and see if they're actually obscure. If you don't want to trust google, open Grizmek's Animal Life Encyclopedia or anything of the kind. They're called fish everywhere; fish has meant non-tetrapod vertebrate since Linnaeus at least, it shows up that way in most biology texts, and it's proved a perfectly useful term.

Yet now, after centuries of use without confusion by biologists and laypeople alike, I'm getting told the terms never really made any sense in the first place. It feels like some people have spent so long looking at cladograms, they can only see things defined strictly by lineage, and have forgotten there's any other way or reason to look at the organisms sitting on top of them. Is it really impossible to understand the idea of groups like reptiles, fish, dicots, bryophytes, protozoa, prokaryotes, and so on, even though so many biologists have been comfortable using them?

User avatar
tigerhawkvok
Posts: 18
Joined: Mon Jan 21, 2008 8:51 pm UTC
Location: Berkeley, CA
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby tigerhawkvok » Wed May 15, 2013 6:08 am UTC

chenille wrote:
tigerhawkvok wrote:Of course they're reptiles. Not calling them such has always been dicey.

If birds were obviously reptiles from general similarity, you would have expected them to have been called so a long time ago. Instead, biologists considered them separately for several hundred years, even after Huxley proposed birds evolved from reptiles, even after their physiology was better understood; in many circles they still are. It seems dicey now because you're insisting on seeing everything in terms of evolutionary pathways and specific traits that concern them; open any biology textbook from more than a decade or two ago, and you'll see that hasn't always been the perspective at all.

Yes, even Huxley proposed that. It was largely denied for philosophical and emotional reasons. In fact, similar reasons to why people assumed extinct dinosaurs must have been slow and dimwitted. "They're dead, of course they were inferior, they can't be competitive with stuff today". The same reason people have tended to be hesitant to accept potential interbreeding of modern humans and Neanderthals, and the same reason that, even though we (probably) should be in the same genus as (at least) bonobos, we have our own genus. These things certainly have an emotional component, and it's important to realize this when you're defending historical positions and try to evaluate with no preconceptions using objective fact.

Think of how insistent people were (and to some extent, still are) insistent that parrots merely mimic, until the amazing results and long documentation with Alex ( https://en.wikipedia.org/wiki/Alex_(parrot) )
tigerhawkvok wrote:99% of the renaming people wouldn't even notice, anyway. How many people know what a coelacanth is? I've even gotten blank stares about "lungfish". I hardly see the problem in excluding sarcopterygia from fishes.

Most people I know have heard of coelocanths (and lungfish), and definitely consider them fish; that's how the fishermen who discovered and ichthyologists who characterized them thought of them, and that's how they show up in most books and documentaries. And if you're interested in structure, biomechanics, chemistry, neurology, or ecology, it doesn't make much sense not to call them fish, because they are only separated by a few peculiarities like odd fins. The only perspective where they're completely different is phylogenetics.

Really? Structural people would care about the phylogenetics -- those "odd fins" and such make a world of difference.
Biomechanically we're *still* not talking about all "fishes". The biomechanics between thunniform, rajiform, anguilliform, (sub)carangiform, and ostraciiform mean that you're looking at niches of fishes and other aquatic animals. You could even include mosasaurs in your analysis, which is a *lizard*.
Neurologically you'd be concerned about, well, the neurology of the situation. The complexity matters, not especially what type of critter it is (insofar as it can be divorced from complexity).
Ecologically, you're still talking about niches.

I think your most convincing argument there is for chemistry, since "swimmy things with gills" will have a different biochemistry than "swimmy air breather with watertight skin" and "swimmy air breather with permeable skin".
And seriously, sharks and rays are called fish all the time. I'll believe that's not your personal experience, especially seeing as how you don't seem to talk to many people about fish. But it's not simply my education. Try looking up the "largest fish", search for the terms "cartilaginous fish" and "jawless fish" anywhere you like, and see if they're actually obscure. If you don't want to trust google, open Grizmek's Animal Life Encyclopedia or anything of the kind. They're called fish everywhere; fish has meant non-tetrapod vertebrate since Linnaeus at least, it shows up that way in most biology texts, and it's proved a perfectly useful term.

Yet now, after centuries of use without confusion by biologists and laypeople alike, I'm getting told the terms never really made any sense in the first place. It feels like some people have spent so long looking at cladograms, they can only see things defined strictly by lineage, and have forgotten there's any other way or reason to look at the organisms sitting on top of them. Is it really so hard to see the sense in groups like reptiles, fish, dicots, bryophytes, protozoa, prokaryotes, and so on, even though so many other biologists have found them useful?


Are you really falling back to Argumentum ad populum? That seems to be the bulk of your argument. "Historically, it has been like so. Older texts say so, as does popular media."

I've already stated that there are ways to define most of those almost identically but monophyletically, and given some examples. And others are a glorified way of talking about interest -- "herpetology" is harmless in that way (these are often polyphyletic). It *is* nonsensical when it is used to define a group that would otherwise be monophyletic except you want to exclude it for particular rhyme or reason (especially when extinct stuff is taken into account!). It'd be like making up a term for "non water living carnivorans" -- slicing out pinnipeds for no good reason. Simply silly.

And really, no one has given a good structural argument for the exclusion of birds from lay-reptiles. You can't even describe *characters* that would artificially exclude them. Non-avian dinosaurs had feathers (diagnostic trait of coelurosauria!), body integument is found all through ornithodira (!) endothermy in at least some members of all crown-group archosaurs (see upright crocodylomorphs like Raisuchus), toothless beaks abound in ornithodira .... the only reason anyone has given is exclusion by fiat, which is no reason at all.

EDIT: Simple test. See if your term can *predict* things about the interior of the critters before you open them up (bonus points for DNA). If it's a total crapshoot, the term needs to be revisited, or be consigned to hobbyist/broad interest categories (much in the way you wouldn't walk up a lizard and say, "oh, a herp!" but you can go out "herping" to mean you're looking for the set of [amphibians,lizards,turtles], and "herp" wouldn't predict really anything about the animal in question whereas even "lizard" certainly would). It's like "movies that get my pulse going" is a perfectly fair descriptor for movies you like, but that's not ever how you'd describe a movie if someone asked you what type of movie "Psycho" was. Convenient post-hoc bucket, maybe, but useless for discussion and really shouldn't be used for discussion because you can't think about it or draw any amount of real inference past what you've defined the bucket to be.

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 26822
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby gmalivuk » Wed May 15, 2013 6:22 am UTC

When debating the meanings of common words, arguments from popularity are not only completely valid, but are perhaps even the only kinds of arguments that are.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

User avatar
tigerhawkvok
Posts: 18
Joined: Mon Jan 21, 2008 8:51 pm UTC
Location: Berkeley, CA
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby tigerhawkvok » Wed May 15, 2013 6:45 am UTC

gmalivuk wrote:When debating the meanings of common words, arguments from popularity are not only completely valid, but are perhaps even the only kinds of arguments that are.

No one is trying to change the type of thing the words refer to. However, the "type of thing" has a precise meaning (or has to garner one if it's to be of use in any discussion), which means that new information can render what falls into that "type of thing" bucket to change over time.

It's like "fruit" might have historically meant "sweet things from trees" but as people found more and more types of plants it became clear that the term wasn't very useful if there wasn't a good way to make the term meaningful and predictive. So, fruit has one definition, and vegetable another. So, tomatoes are a fruit by virtue of being seed bearing.

It's like "frog" and "toad" were meaningfully distinct in Europe, but meaningless worldwide, now applied ad-hoc to common names (of which there are many for a given species), but now it's accepted that if "toad" means anything at all, it refers to just the genus _Bufo_ (and perhaps a few sister clades). Similarly with "salamander" and "newt". "Newt" is kind of meaningless.

On all of those terms you have people that are holding onto the old phrasing, but it's slowly giving way to a more meaningful phrasing.

More uphill battle? "raspberry", "blackberry", and "strawberry" are not a one a berry. A banana is, though.

tl;dr: more information changes things, and language has to catch up to stay relevant. It always has, always will, and most of the argument is coming from "this is inconvenient to relearn". Language is dynamic, help play a role in making it *accurate* on things we know better about now.

User avatar
Pfhorrest
Posts: 5475
Joined: Fri Oct 30, 2009 6:11 am UTC
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby Pfhorrest » Wed May 15, 2013 7:01 am UTC

I feel like I'm in a weird position in this argument between tigerhawkvok and gmalivuk.

I think that we should try to actively shape our language into something better, more useful, more informative in and of itself.

However, I also think that historical usage has precedence in determining the correct use of a word.

This is why I'm all for coining new terms for the newly-discovered natural groupings of organisms, and introducing those terms into common usage, e.g. I think it would be great if common people knew what "amniote" meant and that the things they call mammals, birds, and reptiles all belong in that category, unlike amphibians, fish, etc; but I think it's a horrible idea to try to reappropriate existing words to mean something that diverges from their historical uses, e.g. calling birds reptiles.

For a computer language analogy, we need to maintain backward compatibility while also introducing new and improved features. Even if the new features and old features overlap, and maybe the old ones get deprecated and their use is discouraged as less useful than the new features, they're still there and the code should still run the same, and when support is finally dropped, trying to call those routines should generate an instant error (no such routine) rather than doing something unexpected. (E.g. it's fine if in the future nobody understands what a "reptile" is if the paraphyletic sense of that term is no longer useful, and people talk exclusively about "sauropsids" or "amniotes" instead, but it's not fine if people who continue using "reptile" they way it's always been used are suddenly misunderstood and taken to be saying something else that's wrong and wasn't meant).
Forrest Cameranesi, Geek of All Trades
"I am Sam. Sam I am. I do not like trolls, flames, or spam."
The Codex Quaerendae (my philosophy) - The Chronicles of Quelouva (my fiction)

User avatar
tigerhawkvok
Posts: 18
Joined: Mon Jan 21, 2008 8:51 pm UTC
Location: Berkeley, CA
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby tigerhawkvok » Wed May 15, 2013 7:05 am UTC

Pfhorrest wrote:I feel like I'm in a weird position in this argument between tigerhawkvok and gmalivuk.

I think that we should try to actively shape our language into something better, more useful, more informative in and of itself.

However, I also think that historical usage has precedence in determining the correct use of a word.

This is why I'm all for coining new terms for the newly-discovered natural groupings of organisms, and introducing those terms into common usage, e.g. I think it would be great if common people knew what "amniote" meant and that the things they call mammals, birds, and reptiles all belong in that category, unlike amphibians, fish, etc; but I think it's a horrible idea to try to reappropriate existing words to mean something that diverges from their historical uses, e.g. calling birds reptiles.

For a computer language analogy, we need to maintain backward compatibility while also introducing new and improved features. Even if the new features and old features overlap, and maybe the old ones get deprecated and their use is discouraged as less useful than the new features, they're still there and the code should still run the same, and when support is finally dropped, trying to call those routines should generate an instant error (no such routine) rather than doing something unexpected. (E.g. it's fine if in the future nobody understands what a "reptile" is if the paraphyletic sense of that term is no longer useful, and people talk exclusively about "sauropsids" or "amniotes" instead, but it's not fine if people who continue using "reptile" they way it's always been used are suddenly misunderstood and taken to be saying something else that's wrong and wasn't meant).

Idealistically, I think I'm in favor of this more than my practical position, but I think that's even MORE of an uphill battle.

chenille
Posts: 430
Joined: Tue Dec 20, 2011 7:25 pm UTC

Re: 1211: "Birds and Dinosaurs"

Postby chenille » Wed May 15, 2013 7:08 am UTC

tigerhawkvok wrote:Are you really falling back to Argumentum ad populum? That seems to be the bulk of your argument. "Historically, it has been like so. Older texts say so, as does popular media."

Yeah, except in the few cases where people accept a regulatory body, the meaning of words is determined by how they are generally used. And I didn't only point to old texts and popular media, I pointed out that meaning of fish is found throughout biology texts even today, except for some phylogenetics that tries to avoid non-clades.

I understand full well the reason the value of monophyletic groups; what I am pointing out is that people including biologists also have use for words for some partial groups, too. The main reason I brought up its prevalence in history and popular writing is it shows using fish or reptile in that manner has actually been really intuitive, not confusing or sketchy like you claimed. Of course you could radically redefine them to be clades, but if they're found useful the way they are, it isn't necessary and is in fact more likely to create confusion than resolve it.

Anyway, after claiming "fish" may as well mean actinopterygian based on your personal experience and how few of your friends know about coelocanths, accusing me of fallacious reasoning for pointing out how most authors actually use the word is being a really poor sport.

User avatar
tigerhawkvok
Posts: 18
Joined: Mon Jan 21, 2008 8:51 pm UTC
Location: Berkeley, CA
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby tigerhawkvok » Wed May 15, 2013 7:33 am UTC

chenille wrote:
tigerhawkvok wrote:Are you really falling back to Argumentum ad populum? That seems to be the bulk of your argument. "Historically, it has been like so. Older texts say so, as does popular media."

Yeah, except in the few cases where people accept a regulatory body, the meaning of words is determined by how they are generally used. And I didn't only point to old texts and popular media, I pointed out that meaning of fish is found throughout biology texts even today, except for some phylogenetics that tries to avoid non-clades.

I understand full well the reason the value of monophyletic groups; what I am pointing out is that people including biologists also have use for words for some partial groups, too. The main reason I brought up its prevalence in history and popular writing is it shows using fish or reptile in that manner has actually been really intuitive, not confusing or sketchy like you claimed. Of course you could radically redefine them to be clades, but if they're found useful the way they are, it isn't necessary and is in fact more likely to create confusion than resolve it.

It is absolutely confusing or sketchy (or, can be) if you try to use it descriptively rather than in a bulk, general bucket sense. If you have a container of mostly actinopterygians, a ray, a shark, a lamprey, and a coelacanth, no one is going to say "oh, I thought you said *fish*". This would be like saying "I went on a hike and caught herps". The broad paraphyletic bucket term is fine and even useful in this context.

However, turning around and telling someone "I have a fish in my tank at home" no one would reasonably expect a shark, ray, lamprey, or a lungfish in mud. The term's descriptive and predictive value is already very nearly actinopterygians, and we're trying to use the terms in two different ways, which is unnecessarily unclear. In what are only marginally different use cases, the expectation is entirely different for the *same word*. It's the very picture of an unclear term.
Anyway, after claiming "fish" may as well mean actinopterygian based on your personal experience and how few of your friends know about coelacanths, accusing me of fallacious reasoning for pointing out how most authors actually use the word is being a really poor sport.

I mean general public. People I know (almost) universally know these things, either because they're also interested or I have long since bombarded them with information. However, also having worked with animal sales, I can tell you that most people will stare at you glassy eyed when you say that a lungfish needs air, or ask you if a mudskipper is a frog because it's out of the water, never mind the fins (hell, that one's even an actinopterygian, I shudder to imagine what they'd think an aestivating lungfish was). I'm not talking about one-off anecdotes. I'm talking about these mistakes being made *daily* by *several people per day*.

I also mean practically, as extant non-tetrapod sarcopterygian diversity is really rather limited.

damny
Posts: 1
Joined: Wed May 15, 2013 7:28 am UTC

Re: 1211: "Birds and Dinosaurs"

Postby damny » Wed May 15, 2013 8:26 am UTC

Pfhorrest wrote:I think that we should try to actively shape our language into something better, more useful, more informative in and of itself.


That's how we arrived at this point in the first place, where fish are things that live in water, birds are living things that can fly, fruit are things that grow on plants and are sweet, vegetables are things that grow on plants and aren't sweet, and so on. "Better" and "more useful" generally means the information is more relevant to what you're trying to do with it. The vast majority of people doesn't sort living things into scientific categories, it tries to eat them. The terms "fruit" and "vegetables" originated as "things that grow on plants that you work for" vs. "all plants" and then gradually changed to "plant parts that you enjoy eating" vs "plant parts that you can also eat". Then science comes along and takes the outdated and much too broad definition of vegetable, where it refers to all plant matter, and makes up a new definition of fruit that describes plant parts that contain seeds and is equally too broad. This doesn't work as it's contrary to the actual direction language has been evolving in, namely sorting plant parts into categories according to what we do with them in the kitchen.

The same applies to birds and dinosaurs. Unless we can resurrect a T-Rex and it turns out it has to be prepared like chicken, I can guarantee you that the knowledge that it's impossible to come up with a monophyletic clade that includes birds but not dinosaurs will remain entirely useless for most people, and irrelevant to their definition of birds as things that can fly vs. dinosaurs as things that lived ages ago that you go to a museum to learn about. Because those definitions are actually useful in real life, they will stick.

I think it would be great if common people knew what "amniote" meant and that the things they call mammals, birds, and reptiles all belong in that category, unlike amphibians, fish, etc; but I think it's a horrible idea to try to reappropriate existing words to mean something that diverges from their historical uses, e.g. calling birds reptiles.


I'd expect this to be easier than trying to establish new definitions for existing terms. If you tell some random person that birds are really dinosaurs, they might, if they trust you, memorize it and parrot it to their friends, but the reasoning behind it will be lost along the way. On the other hand, if you tell them that what differentiates birds and dinosaurs and mammals from fish is that they don't lay eggs in water, that's both easy to understand and more likely to stick because there is no conflict with existing definitions. You still have the problem that it's utterly useless knowledge for most people, but at least there is no conflict with existing knowledge that's actually useful for them.

New terms can be problematic too, though. Calling your clade "terrible lizards" is great at providing something your children can brag about knowing for generations, but it's horrible if you actually want to further understanding among non-scientists. Now the first thing children learn about dinosaurs is that they're slightly bigger lizards. Great job there, science.

User avatar
Klear
Posts: 1965
Joined: Sun Jun 13, 2010 8:43 am UTC
Location: Prague

Re: 1211: "Birds and Dinosaurs"

Postby Klear » Wed May 15, 2013 9:40 am UTC

tigerhawkvok wrote:(much in the way you wouldn't walk up a lizard and say, "oh, a herp!" but you can go out "herping" to mean you're looking for the set of [amphibians,lizards,turtles], and "herp" wouldn't predict really anything about the animal in question whereas even "lizard" certainly would).


I'm sorry... I couldn't resist:

Image

Now... ehm... please continue. The discussion is really stimulating.

tofudragon7
Posts: 6
Joined: Tue May 14, 2013 8:28 pm UTC

Re: 1211: "Birds and Dinosaurs"

Postby tofudragon7 » Wed May 15, 2013 10:43 am UTC

Hmm, time to get back and make some replies/rebuttals.

First, I'd like to point out that my annoyance is primarily with the wording of this comic: stating "by any reasonable definition" is extremely disingenuous in this case (and an example of scientific weasel-wording) when, by almost every real biologist's metric, T. rex is more similar to a Stegosaurus. (But someone who did a bit of research first would find that there are plenty of other dinosaurs less related to a Tyrannosaur than today's birds are, such as any mid-to-late Cretaceous ornithischian).

tigerhawkvok wrote:Relatedness in biology is based on "shared derived characteristics" (changes), or "synapomorphies".

Nope, this is wrong. Relatedness in biology is, in fact, based on genetic similarity (search wikipedia for "relatedness"; this forum isn't letting me post a link for some reason). If you take a class on population genetics, you'll learn that the biggest indicator of this is usually evolutionary distance (measured in millions of years). Synapomorphies, on the other hand, are traits that are determined to be the result of relatedness, and are used to establish cladistic hierarchies far more often than actual direct similarity.

tigerhawkvok wrote:During that period from 230mya -> 150ish mya, the saurischian/theropod lineage accumulated a bunch of changes that *all of them share* that were never accumulated in the ornithischian lineage.

Bingo! But you appear to have missed the point of my argument. The therapods got a good 80 million year run to evolve new traits not found in ornithischians. Of course, in the period from 160 mya to the present, birds got twice as long to evolve traits not found in Tyrannosaurs, so I don't see how this could be an argument for more similarity between T. rex and modern birds (extinct birds, maybe).

tigerhawkvok wrote:we have birds sharing with _T. rex_ that it doesn't share with _Stegosaurus_:
Lacrimal exposed on dorsal skull roof, cervicals 3-6 longer than axis...

Oh boy, a bunch of anatomical differences. But how many things do birds not share with Tyrannosaurs, and how would you quantify this? (I don't have any paleontology books sitting on my desk, but here's a few off the top of my head: hollow bones, lack of teeth, existence of a beak, extra neck vertebrae, fused collarbones... in short, some pretty darn significant differences)

tigerhawkvok wrote:The temporal problem becomes clear when you realize that the distance from us to Compsognathus (us->basal amniotes = +340 MY, basal amniote -> Chasmatosuchus, basal psuedosuchian = +90 MY = ~430 MY) is about the same temporal distance from us to Dimetrodon, also a synapsid like us ( ~ 380 MY temporal distance), which is clearly false.

Two things. First, we are a lot more similar to a Dimetrodon than to a Compsognathus; this is because that extra fifty million years is actually quite a lot of time, in which Compsognathus diverged quite significantly from the common ancestor we share with it.
Second,, the Compsognathus passed through a significant extinction event that the Dimorphodon did not (the T-J extinction), and extinctions are often followed by greater changes in both morphological and genetic variation. Considering that birds also went through more significant extinctions in their split from Tyrannosaurs than Stegosaurs did, this also supports my original point.

Eebster the Great wrote:Your theorycrafting won't convince me as much as actual fossil evidence. The fact of the matter is that morphologically, birds and T. rex are much more similar than T. rex and Stegosaurus.

I believe you're the one presenting theorycrafting as evidence. Maybe T. rex is more morphologically similar to a modern bird than a Stegosaurus, but that's not how any biologist would define "relatedness." Besides, all we have access to is fossilized bones (and a few feathers); bone structure is often only a part of morphological variation (and is scored very arbitrarily), so we can't really use this as our best estimate of relatedness when other more reliable metrics exist.

Copper Bezel wrote:A person is more closely related to a grandfather than to an aunt, right? (Not a perfect analogy, since the relatedness meant and the source of new genetic information are different, but they're both still there.)

You're on the right track; they're actually pretty similar concepts of relatedness. However, since you have twograndparents in common with your aunt, this means that you both have the same relatedness (but you're less related to your cousin).


Someday, I may have children, and now I'm wondering how hard I'll have to resist the urge to teach them that whales are the world's largest fish and giraffes the tallest amphibians.

The Cat

Re: 1211: "Birds and Dinosaurs"

Postby The Cat » Wed May 15, 2013 12:08 pm UTC

Dude come on.png
Dude come on.png (46.87 KiB) Viewed 7154 times
Last edited by The Cat on Wed May 15, 2013 3:21 pm UTC, edited 1 time in total.

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 26822
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby gmalivuk » Wed May 15, 2013 2:31 pm UTC

tigerhawkvok wrote:Idealistically, I think I'm in favor of this more than my practical position, but I think that's even MORE of an uphill battle.
Really? But we invent and learn new words all the time.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

Misanthropic Scott
Posts: 35
Joined: Mon Apr 08, 2013 7:38 am UTC

Re: 1211: "Birds and Dinosaurs"

Postby Misanthropic Scott » Wed May 15, 2013 2:35 pm UTC

Pfhorrest wrote:I'm arguing the same with regards to "dinosaurs". That's a word already in common usage to describe a group of animals which, as it turns out, is paraphyletic, because birds share the same common ancestor but aren't counted in it. Rather than redefining the common word to mean something no non-specialist would use it to mean, why can't we come up with a new technical term (like "avesaurs") for the monophyletic group, like we have "sauropsida" for the group containing all modern reptiles and birds?

The word is dinosauria, if we need to use the scientific word already in semi-common usage. The problem with any paraphyletic definition is that you're essentially saying dinosaurs == dinosauria - aves. It's like saying that family == family - second cousin because I don't like my second cousin. Any English language word that does not map to a clade/taxa is not mapped to any scientific concept. It's fine to have such words in the English language. They just don't mean as much due to their complete arbitrariness.

Imagine a world where all birds were also extinct by 65.3 MYA. We wouldn't be having this conversation, would we?

We would just be calling them dinosaurs. The difference comes only from our familiarity with living birds making some on this board think that they're boring. So, we don't like birds because we're already familiar with them. So, like excluding second cousins from family because some people don't get along with their second cousins, some people find birds boring for having been better at surviving the impact event than their larger cousins, so want to exclude them from the family.

It's silly.

Misanthropic Scott
Posts: 35
Joined: Mon Apr 08, 2013 7:38 am UTC

Re: 1211: "Birds and Dinosaurs"

Postby Misanthropic Scott » Wed May 15, 2013 2:37 pm UTC

Eebster the Great wrote:But "dinosaur" is a technical term, just one that has now entered into common vocabulary. Dinosaurs are the clade consisting of Triceratops, birds, their MRCA, and all its descendents. What you are proposing is actually redefining the word to accommodate general ignorance.


Extremely well said! Thanks.

Misanthropic Scott
Posts: 35
Joined: Mon Apr 08, 2013 7:38 am UTC

Re: 1211: "Birds and Dinosaurs"

Postby Misanthropic Scott » Wed May 15, 2013 2:44 pm UTC

EgregiousCharles wrote:... or computer programmers telling everyone else that it isn't really a kilometer unless it's 1024 meters.


As an anal-retentive computer programmer (i.e. geek), I'd like to point out that this minor tangential issue has already been solved.

http://physics.nist.gov/cuu/Units/binary.html

1024 meters is a kibimeter.

Misanthropic Scott
Posts: 35
Joined: Mon Apr 08, 2013 7:38 am UTC

Re: 1211: "Birds and Dinosaurs"

Postby Misanthropic Scott » Wed May 15, 2013 2:49 pm UTC

tofudragon7 wrote:this forum isn't letting me post a link for some reason


When you hit 5 posts, you can post links.

WriteBrainedJR
Posts: 160
Joined: Tue Apr 16, 2013 3:08 pm UTC
Location: Right Behind You
Contact:

Re: 1211: "Birds and Dinosaurs"

Postby WriteBrainedJR » Wed May 15, 2013 2:56 pm UTC

tigerhawkvok wrote:It's like "fruit" might have historically meant "sweet things from trees" but as people found more and more types of plants it became clear that the term wasn't very useful if there wasn't a good way to make the term meaningful and predictive. So, fruit has one definition, and vegetable another. So, tomatoes are a fruit by virtue of being seed bearing.

Nobody outside of a biology classroom (taught by a biology teacher with an incomplete understanding of the way language works) or plant science calls a tomato a fruit more than half the time. The characteristics the average person wants to predict when talking about plants is how it tastes, and how to grow it. A tomato is not sweet, and grows on the ground, so calling a fruit is usually meaningless to the majority of people.

tigerhawkvok wrote:On all of those terms you have people that are holding onto the old phrasing, but it's slowly giving way to a more meaningful phrasing.

More uphill battle? "raspberry", "blackberry", and "strawberry" are not a one a berry. A banana is, though.

You have a very narrow definition of "meaningful." To a whole lot of people, whose needs you seem to be completely fine with disregarding, a group that includes bananas, blueberries and tomatoes is practically meaningless. How useful is the phrase "many edible plants with skin?" That's how useful the scientific understanding of the term "berry" is to most people.

That's why in the real world, we have the common parlance, and different, field-specific vocabulary. The common usage of the word "berry" is meaningful to people who are curious about the taste, juice, size and shape of a fruit. The scientific usage of the word is useful to scientists.

I know good biology teachers who actually teach it this way; that the words scientists use often have different, equally useful meanings, in contexts outside of science.

tigerhawkvok wrote:tl;dr: more information changes things, and language has to catch up to stay relevant. It always has, always will, and most of the argument is coming from "this is inconvenient to relearn". Language is dynamic, help play a role in making it *accurate* on things we know better about now.

You're half right. A language must remain useful to remain relevant. Attempting to force changes to the vocabulary that would actually make it less useful to the majority of people, as you seem to want to do, never, ever works. Ask a French person about the Académie.

For the record, attempting to modify the meaning of the word "dinosaur" in common usage is a somewhat less extreme example than trying to re-write the dictionary on food.

EDIT: Somehow ended up repeating myself. Stupid copy-paste.
Last edited by WriteBrainedJR on Wed May 15, 2013 2:58 pm UTC, edited 1 time in total.

User avatar
orthogon
Posts: 3100
Joined: Thu May 17, 2012 7:52 am UTC
Location: The Airy 1830 ellipsoid

Re: 1211: "Birds and Dinosaurs"

Postby orthogon » Wed May 15, 2013 2:58 pm UTC

Misanthropic Scott wrote:
EgregiousCharles wrote:... or computer programmers telling everyone else that it isn't really a kilometer unless it's 1024 meters.


As an anal-retentive computer programmer (i.e. geek), I'd like to point out that this minor tangential issue has already been solved.

http://physics.nist.gov/cuu/Units/binary.html

1024 meters is a kibimeter.


Or has it? I would say that 1024 meters is the contents of a well-stocked test-equipment shop. 1024 metres is a kibimetre. :evil:

The problem with "kibi" (and to some extent the other binary prefixes) is that it sounds like a diminutive, not an augmentative. (This is probably a result of the high vowel sounds, cf teeny-weeny etc.)
xtifr wrote:... and orthogon merely sounds undecided.

chenille
Posts: 430
Joined: Tue Dec 20, 2011 7:25 pm UTC

Re: 1211: "Birds and Dinosaurs"

Postby chenille » Wed May 15, 2013 2:59 pm UTC

Misanthropic Scott wrote:Any English language word that does not map to a clade/taxa is not mapped to any scientific concept.

That's a really bold claim, and one that doesn't pan out at all. Prokaryote is not a clade and usually doesn't get treated as a taxon, but it's still a perfectly legitimate term, in that it gives you a fair bit of description about the organism in question. Not to mention groups like digitigrades, or herbivores, or planets, all of which are useful scientific concepts despite not being things you can mechanically read off a phylogenetic tree. I'm sure you would recognize those as valid; yet the moment there's a hint phylogeny was partly considered in defining a word, suddenly you introduce some dogmatic standard where it has to the entire definition to be "scientifically" valid, regardless of what actual use by scientists is.

Why is it so hard to see that other types of terms could be useful to biologists, too? The phrase "non-avian dinosaurs" gets over a thousand hits on google scholar, and yet introducing a shorter word for it would be non-scientific? That conception of language doesn't make any sense to me.

Misanthropic Scott wrote:Imagine a world where all birds were also extinct by 65.3 MYA. We wouldn't be having this conversation, would we?

And in a world where they looked exactly like crocodiles, we wouldn't be having this conversation, either. But why do you think we should base our language on worlds we don't live in, instead of tailoring them to describe the features of the one we actually do?
Last edited by chenille on Wed May 15, 2013 3:31 pm UTC, edited 4 times in total.

The Cat

Re: 1211: "Birds and Dinosaurs"

Postby The Cat » Wed May 15, 2013 3:18 pm UTC

Shake your Booty.jpg

Misanthropic Scott
Posts: 35
Joined: Mon Apr 08, 2013 7:38 am UTC

Re: 1211: "Birds and Dinosaurs"

Postby Misanthropic Scott » Wed May 15, 2013 3:33 pm UTC

chenille wrote:
Misanthropic Scott wrote:Any English language word that does not map to a clade/taxa is not mapped to any scientific concept.

That's a really bold claim, and one that doesn't pan out at all. Since the current examples are disputed, I'll offer another: prokaryote is not a clade and usually doesn't get treated as a taxon, but it's still a perfectly legitimate term, in that it gives you a fair bit of description about the organism in question. Not to mention groups like digitigrades, or herbivores, or planets, all of which are useful scientific concepts despite not being things you can mechanically read off a phylogenetic tree. I'm sure you would recognize those as valid; yet the moment there's a hint phylogeny was partly considered in defining a word, suddenly you assume this dogmatic standard on how it has to be done to be scientific. It doesn't make sense to me.


Planet. Good point. I meant English language words purported to be for families of organisms. Herbivore is generally used as a term to describe animals by behavior, not familial relationship. Carnivore is doubly confusing as it maps both to a clade and a behavior and one must be clear which meaning one is using at any given moment.

Words like reptile, where reptile == saurapsid - dinosauria, are confusing. They are like saying family == family - second cousin. Why the omission? Why would we actively want a word like reptile that doesn't include all saurapsids? What's the positive effect of such words? Do we have a reason for obfuscation of parentage? Please tell me the benefit of having such words.

chenille wrote:
Misanthropic Scott wrote:Imagine a world where all birds were also extinct by 65.3 MYA. We wouldn't be having this conversation, would we?

And in a world where they looked exactly like crocodiles, we wouldn't be having this conversation, either. But why do you think we should base our language on worlds we don't live in, instead of tailoring them to describe the features of the one we actually do?


Imagine a world without hypothetical situations.

The point of my hypothetical in this instance was to show the arbitrariness of stating that dinosaurs == dinosauria - aves. The only reason we think differently about birds is because many are still alive today. That seems to be a fairly silly characteristic on which to base our descriptions of family. So, now, you're arguing that family == family - great great great grandparents because presumably no one alive today has a living great great great grandparent.

User avatar
Diadem
Posts: 5654
Joined: Wed Jun 11, 2008 11:03 am UTC
Location: The Netherlands

Re: 1211: "Birds and Dinosaurs"

Postby Diadem » Wed May 15, 2013 3:38 pm UTC

tigerhawkvok wrote:
Diadem wrote:
ahammel wrote:How about "the rules of modern systematics prevent biologists from defining a taxon which includes Stegosaurs and Tryranosaurs but excludes modern birds"?

This is only true if you require every taxon to be a clade. However if you do that, you are begging the question, because that is precisely the point where the disagreement is about.

A taxon is just a group of one or more populations of organisms. While modern biology generally tries to do taxonomy according to evolutionary links, there is no formal requirement for such a link when defining taxons, and there is certainly no requirement for a taxon to be monophyletic. If you're only interested in the evolutionary history of life on earth, then monophylecity is the way to go. But taxonomy is not just about evolutionary distance, it's about describing similarities and differences between species.

Evolution isn't a constant factor that makes all species diverge exactly as fast all the time. Sometimes one species in a group of related species diverges much more rapidly from the others than the others diverge from each other. If you want to do serious taxonomy you have to recognize this, and thus you have to introduce paraphyletic groups.

Taxonomy without paraphyletic groups is not taxonomy at all. It is just describing evolutionary relatedness.

I don't know about birds and dinosaurs. I'm no expert in that particular area. But the idea that birds have to be dinosaurs because otherwise dinosaurs are paraphyletic is just silly.


Patent nonsense. If you don't require every taxon to be a clade, then you can construct taxons on any arbitrary grouping of characteristics (and bear in mind you're implictly arguing here that many, if not all, definitions of taxon, including non-cladistic ones, are valid). This means I can create a taxon with the characteristics "bilaterally symmetrical, no limbs" and you get a "taxon" consisting of worms, caecilians, snakes, eels, polychaetes, etc. This is a simple grouping that by itself demonstrates how *useless* such groupings can be. It includes terrestrial, arboreal, fossorial, and marine animals, with and without backbones, deuterostomes and protostomes. You garner no information whatsoever from that grouping.

The obvious retort is then "OK, sure, we can agree that's a useless group. But that's too broad of a group! No one would define a group like that". But that's not the point. You've constructed a definition of taxon that doesn't prohibit that from being a valid taxon. So, praytell, how do you restrict taxon definitions in a way that is not explicitly evolutionary but doesn't accept obviously bogus "taxons" as valid? I'd love to see it. And until you can produce such a definition, I'll reiterate -- your point is patently silly.

Using a hammer and some nails, I can make many completely useless wooden structures. By your logic, this means that the entire profession of carpentry is patently silly. I fear however that it is your logic that is patently silly. Of course you can define plenty of useless groups. So what? The point of taxonomy is to define useful groups. The fact that you can do taxonomy badly, if you want to, is no argument against taxonomy at all.

You know, I'm just going to repeat myself, because no one seems to want to respond to this argument: Taxonomy is not about tracking evolutionary relatedness. Taxonomy is about groups organisms in a useful way. Evolutionary relatedness is one very important part of this, but it's not the only one. And anyway, insisting on using only monophyletic groups is not even tracking evolutionary relatedness, but merely distance to the MRCA.

Copper Bezel wrote:But I'm defending chenille's position more than Diadem's, and I'd like to hear Diadem chime in on whether or not polyphyletic groups are allowed.

They aren't disallowed in principle. Though I can't think of a single example where such a grouping would be useful. At least in a scientific context. Outside science such groups are often useful ('fruit' is one, for example). But within science, no, I can't think of an example. But that doesn't mean such examples are impossible in principle. So banning polyphyletic groups on a matter of principle seems silly.

It's easy to construct examples by the way. Imagine that it turns out that not all live on earth evolved from the same ancestor. Maybe live evolved independently several times. Does this mean that we are no longer allowed to use the term 'organism' for some organisms?

A rigid insistance on monophyleticy is just silly. There's more to biology than evolution, and there's more to evolution than "Time to MRCA".
It's one of those irregular verbs, isn't it? I have an independent mind, you are an eccentric, he is round the twist
- Bernard Woolley in Yes, Prime Minister

User avatar
Klear
Posts: 1965
Joined: Sun Jun 13, 2010 8:43 am UTC
Location: Prague

Re: 1211: "Birds and Dinosaurs"

Postby Klear » Wed May 15, 2013 3:54 pm UTC

Misanthropic Scott wrote:Words like reptile, where reptile == saurapsid - dinosauria, are confusing. They are like saying family == family - second cousin. Why the omission? Why would we actively want a word like reptile that doesn't include all saurapsids? What's the positive effect of such words? Do we have a reason for obfuscation of parentage? Please tell me the benefit of having such words.


I've never in my life needed a word for the group of animals which includes what I understand as dinosaurs and birds. When talking about dinosaurs, in 99% cases you mean the extinct non-flying giant lizard-looking buggers, the 1% that remains is this thread.

Oh, and please don't lynch me for my hyperbole. I understand there are contexts, mostly scientific, where adding birds to the mix is right and useful, but I'm pretty sure they're in a minority.

chenille
Posts: 430
Joined: Tue Dec 20, 2011 7:25 pm UTC

Re: 1211: "Birds and Dinosaurs"

Postby chenille » Wed May 15, 2013 4:16 pm UTC

Misanthropic Scott wrote:Words like reptile, where reptile == saurapsid - dinosauria, are confusing. They are like saying family == family - second cousin. Why the omission? Why would we actively want a word like reptile that doesn't include all saurapsids? What's the positive effect of such words? Do we have a reason for obfuscation of parentage? Please tell me the benefit of having such words.

Because words don't have to be strictly about parentage. Are you actually confused why pretty much all biologists until the last decade or so treated birds and reptiles as separate, even though they understood birds evolved from somewhere within the reptiles for a long time? It's because most of the family live around one part of character space, but the one cousin and all his descendants moved far away, and so people found it practical to refer to them separately. Obviously any such distinction is really messy for intermediate forms, but I don't understand why the logic behind such a common practice is now incomprehensible to people, if they remember there's more to organisms than their spot on a cladogram.

I'm with Klear. There doesn't seem to be much use for coelurosaurs taken as excluding birds, and the concept seems to have died accordingly. But we have the different words sauropsid and reptiles for the different concepts, and outside of phylogenetics I haven't seen any occasion where the former would be better. The case of dinosaurs are somewhere in the middle, but for the most part there really aren't many other contexts where you need to refer to stegosaurs and sparrows together, and so usually non-avian dinosaur is the more useful concept, as the common appearance of that phrase shows.

User avatar
bmonk
Posts: 662
Joined: Thu Feb 18, 2010 10:14 pm UTC
Location: Schitzoed in the OTT between the 2100s and the late 900s. Hoping for singularity.

Re: 1211: "Birds and Dinosaurs"

Postby bmonk » Wed May 15, 2013 4:39 pm UTC

jpk wrote:Just because I'm curious, how tall was the average dinosaur? And while we're at it, how heavy is the average mammal?

Smaller than you think, in both cases. We focus on the big ones, but the little animals usually outnumber them by a fair margin.

A bit of in-depth research indicates that the average dinosaur was about the size of a good-size car (minivan/station wagon), or a bear, that is about 1 ton. (I thought in earlier years they had said the average was a good-size turkey.) The average mammal is dog sized, or about 12-15 kg.

I might add a moment's thought to the dinosaur vs. birds debate:
Not too long ago, and certainly when I was a child, dinosaurs were seen as reptilian, with scaly skin, where not armored. (Think lizards and snakes, turtles, crocodiles.) Dinosaurs were seen as quite stupid, slow, cold-blooded--on the analogy of reptiles again. Birds have scaly legs, but mostly feathers, and are (relatively) smart, quick, and warm blooded. Obviously, they were two very different kinds of beings.

Nowadays, many dinosaurs--perhaps all therapods--are suspected of having feathers. They are quick, at least semi-warm-blooded, and probably not as stupid as we thought. Some at least cared for nests, like birds do. Now we are not so sure that dinosaurs and birds are different.

We may have to distinguish between types of dinosaurs--say, include the therapods as birds? Add the Sauropodomorpha as well?--because of these bird-like characteristics, but leave the Ornithischia as "true dinosaurs," because they are more "traditionally" reptilian.

The real problem is that our view of dinosaurs--or at least certain types--has changed so much in recent decades.

Klear wrote:I've never in my life needed a word for the group of animals which includes what I understand as dinosaurs and birds. When talking about dinosaurs, in 99% cases you mean the extinct non-flying giant lizard-looking buggers, the 1% that remains is this thread. [emphasis added]

But just how lizard-looking were they? Did they have feathers? Were they warm-blooded, and run around like birds?
Having become a Wizard on n.p. 2183, the Yellow Piggy retroactively appointed his honorable self a Temporal Wizardly Piggy on n.p.1488, not to be effective until n.p. 2183, thereby avoiding a partial temporal paradox. Since he couldn't afford two philosophical PhDs to rule on the title.

User avatar
bmonk
Posts: 662
Joined: Thu Feb 18, 2010 10:14 pm UTC
Location: Schitzoed in the OTT between the 2100s and the late 900s. Hoping for singularity.

Re: 1211: "Birds and Dinosaurs"

Postby bmonk » Wed May 15, 2013 4:48 pm UTC

ps.02 wrote:Ah but don't forget that "scientist" is a taxonomic mess. For example, computer scientists, despite the name, may actually be more closely related to mathematicians than to what we might call true scientists or euscientists.

So the range of beliefs in the taxonomic or linguistic definitions of bird and dinosaur amongst "scientists" doesn't seem all that important. The real question, of course, is whether Vardaman's mother, in As I Lay Dying, really is a fish. Even if it's not clear from the text whether he is a scientist.

At least (serious?) mathematicians can be defined, more or less, by Erdős number. I don't think that scientists have an equivalent.
Having become a Wizard on n.p. 2183, the Yellow Piggy retroactively appointed his honorable self a Temporal Wizardly Piggy on n.p.1488, not to be effective until n.p. 2183, thereby avoiding a partial temporal paradox. Since he couldn't afford two philosophical PhDs to rule on the title.

chenille
Posts: 430
Joined: Tue Dec 20, 2011 7:25 pm UTC

Re: 1211: "Birds and Dinosaurs"

Postby chenille » Wed May 15, 2013 4:50 pm UTC

bmonk wrote:Nowadays, many dinosaurs--perhaps all therapods--are suspected of having feathers.

From what I have seen, probably not in types like Coelophysis, Dilophosaurs, or Ceratosaurs. Coelurosauria all probably did, with simple feathers in Compsognathus and Tyrannosaurs, branched feathers in Ornithomimids and Oviraptors, and flight feathers in raptors and birds. I haven't seen anything about Spinosaurs, Allosaurs, and Megalosaurs, which are in an evolutionary position between the others.

The Cat

Re: 1211: "Birds and Dinosaurs"

Postby The Cat » Wed May 15, 2013 5:00 pm UTC

I know so many people who will argue until they're blue in the face, just so they can "win" or "be right". Just fighting for a slippery little rock in the pond. understanding and efficiency is gonna increase with generations. I've got a question for the evolutionary biologists. Why the Fuck does a piece of sea pork look like a human liver? They both serve the same function. They're both filter feeders. Can we learn about the human liver by studying sea pork? focus on that, because I likes a libation from time to time. gracias

Spoiler:
sea pork.jpg


Spoiler:
human liver.jpeg
human liver.jpeg (10.09 KiB) Viewed 7062 times
Last edited by The Cat on Wed May 15, 2013 5:10 pm UTC, edited 2 times in total.

User avatar
bmonk
Posts: 662
Joined: Thu Feb 18, 2010 10:14 pm UTC
Location: Schitzoed in the OTT between the 2100s and the late 900s. Hoping for singularity.

Re: 1211: "Birds and Dinosaurs"

Postby bmonk » Wed May 15, 2013 5:03 pm UTC

Himself wrote:
WriteBrainedJR wrote:Birds are dinosaurs in the sense that sliders are hamburgers. If you ignore size, sliders look a lot like hamburgers. Their internal structures are nearly identical to those of hamburgers. But if I order a hamburger and you give me a slider, you'll have a dissatisfied customer on your hands. Same thing with birds and dinosaurs.


Though many dinosaurs were actually quite small. Look an anchiornis. We just tend to think about the big ones more.

I could picture some future species evolving to build a civilization with paleontologists. They study mammals and everyone is abuzz about elephants and bears while hardly anyone gives a second thought to mice.

Also, small animals don't fossilize as well--little bones easily are eaten, or decay, or whatever. And they are harder to find than a bone that is several feet long. So we know more about the big animals than the small ones. But that's true even among living species: Nobody really expects to find a new species of, say, elephants or whales, but new species of mice, or lizards, or worms are common.
Having become a Wizard on n.p. 2183, the Yellow Piggy retroactively appointed his honorable self a Temporal Wizardly Piggy on n.p.1488, not to be effective until n.p. 2183, thereby avoiding a partial temporal paradox. Since he couldn't afford two philosophical PhDs to rule on the title.


Return to “Individual XKCD Comic Threads”

Who is online

Users browsing this forum: orthogon and 99 guests