Evolution, development, and random biological ejaculations from a godless liberal
PZ Myers is a biologist and associate professor at the University of Minnesota, Morris.
…and this is a pharyngula stage embryo.
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…unless one is able to find faint foreshadowings of it in the dryopithecids. Pilbeam assumes that the relationship exists, and has so indicated in a chart he has constructed — although he does leave a huge gap in it, and makes no attempt to link any specific dryopithecid with any living ape. He contents himself with the observation that dryopithecids are primitive apes with certain things in common, things that they do not have in common with a second group of Miocene apes that he has also succeeded in sorting out and lumping together: the ramampithecids, named after the aforementioned Ramapithecus.
What is the distinction? It is a simple but overwhelmingly important one. With the exception of their premolars, which are apelike, all of the ramapithecids have peculiar unapelike teeth: Big molars, heavy enamel, small canines. They foreshadow hominids. The dryopithecids, with apelike teeth, foreshadow modern apes.
"LUCY The Beginnings of Humankind" Donald Johanson & Maitland Edey, Copyright 1981
Generating right-left asymmetries
Modules and the promise of the evo-devo research program
The evolution of deuterostome gastrulation
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« Café Scientifique tonight, in the Twin Cities | Main | Aftermath »
Category: Personal
Posted on: February 13, 2007 4:00 PM, by PZ Myers
Our biology club has a fundraiser tradition: for Valentine's Day, they'll take your picture with our resident snake and print it out as a card (what is it about big snakes and romance, anyway?) Of course I have to participate, so here I am, fondling a big reptile with an even bigger dead reptile in the background.
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Comments
A bit off topic, but ive noticed that the 'view blog reactions' link is all screwed up by the Top 5 panel. Most of the trackbacks seem to be other scienceblogs with the TOP 5 panel rather than actual trackbacks.
OK it was completely off topic, so nice snake.
Posted by: zwa | February 13, 2007 4:07 PM
Careful: You might have some pedants jump in here and complain about dinosaurs not really being reptiles or something.
I forget how it goes.
Posted by: Bronze Dog | February 13, 2007 4:16 PM
substitute 'view blog reactions' for the 'trackbacks' in that previous comment.
Posted by: zwa | February 13, 2007 4:17 PM
Cute. Very cute.
Well, except for the snake part. Are there any animals with hair that you actually like? :)
Posted by: Interrobang | February 13, 2007 4:19 PM
zwa, maybe the browser you're using influnces it?...
What a picture...PZ reminds me of another scientist there, I'm not sure who...
Posted by: Pete K | February 13, 2007 4:22 PM
Well, reptiles are a paraphyletic group (but we will let that pass). You did ask for it Bronze Dog.
Still, I'd like to see more of the Triceratops! It looks very similar to the one that site in the entrance hall to 'my' museum in Munich.
Posted by: Dave Hone | February 13, 2007 4:22 PM
...
...
I haven't seen a boa around anybody's neck like that since the last time Rip Taylor appeared on Hollywood Squares.
...
...
Posted by: Hank Fox | February 13, 2007 4:28 PM
It might just be the snake strangling the beard into shape, but you look like you're about to go leverage some synergies or something.
Posted by: stogoe | February 13, 2007 4:32 PM
Well, I must say... that boa suits you better than the elf outfit, jejeje.
Posted by: Tinni | February 13, 2007 4:37 PM
zwa:
Yeah, I noticed this problem with the "Technorati link cosmos" thingy a while ago.
Nice snake. Does anyone else think this picture makes PZ look a little like a professorial Santa Claus?
Posted by: Blake Stacey | February 13, 2007 4:38 PM
OK, since we are to be jerks about the term "reptile", in reality, the term "Reptile" has no real applicable meaning in biology anymore...
Posted by: Lago | February 13, 2007 4:38 PM
Hm, kinda makes you look like a certain US Republican president.
Posted by: llewelly | February 13, 2007 4:47 PM
The photographer clearly didn't know who s/he was dealing with, otherwise those horns would've looked like they were PZ's...
Posted by: minusRusty | February 13, 2007 4:51 PM
"Nice snake. Does anyone else think this picture makes PZ look a little like a professorial Santa Claus?"
Not quite. Sorry, PZ, great picture, but the reigning professorial Santa Claus is still Dan Dennett.
Posted by: Callandor | February 13, 2007 4:54 PM
caption: "Biologist in Natural Habitat".
I agree with minusRusty. Had the photographer moved to his right the desired effect could have been achieved. Consider the metaphorical symmetry . . .
Posted by: Crudely Wrott | February 13, 2007 5:15 PM
I told you there would be snakes.
Posted by: Greg Laden | February 13, 2007 5:21 PM
Cuteness beyond compare. I wish I could've gotten my senior pictures like that.
Posted by: Karley | February 13, 2007 5:26 PM
Sorry to post off-topic, but did anyone hear this story about a pastor who just got eighteen months in prison for running a baby leopard shark - poaching operation? Apparently he had several members of his church working with him, and (of course) told them they were doing "god's work" [according to NPR this morning]. It's us atheists who lack moral fiber, though.
That snakeis H-O-T, by the way.
Posted by: J Daley | February 13, 2007 5:36 PM
A silver lining, however: fines levied against the pastor, his co-conspirators and church (some $910,000) are all going to help restore a marine wildlife habitat for leopard sharks.
Now that's a faith-based initiative I can dig.
Posted by: J Daley | February 13, 2007 5:41 PM
I came in here to ask if dinosaurs are really reptiles, but it looks like Bronze Dog took all the fun out of doing that :P
Posted by: Aaron Kinney | February 13, 2007 5:52 PM
Uh oh, this is just further evidence that "evil santa" exists.
Just kidding about. Nice photo and a fun idea. But a snake picture for Valentine's Day? Is there some sort of symbolic reference to which I am not privy?
Posted by: beepbeepitsme | February 13, 2007 5:58 PM
Had the photographer moved to his right
I'm just an amateur photographer, but I think the photographer would have had to move to his or her own left to acheive the superposition of the Triceratops horns above PZ's head.
Posted by: TheBrummell | February 13, 2007 6:12 PM
what is it about big snakes and romance, anyway?
Um, shot in the dark here, but... Freud?
Posted by: Chinchillazilla | February 13, 2007 6:12 PM
Sorry about the all-italics at the end there. I was sure I'd closed that tag.
Posted by: TheBrummell | February 13, 2007 6:13 PM
I can't decide which of you three guys is the cutest.
Posted by: weemaryanne | February 13, 2007 6:16 PM
Proof that the YECs are right! This would be the first picture ever taken in the Garden of Eden. Eve is behind the camera and there is Adam and the Snake that started evidence based thinking.
Dinosaurs in Eden, it's a Kent Hovind moment.
Posted by: JohnnieCanuck | February 13, 2007 6:22 PM
I think most systematists have always been happy with the big toothy scaly dinosaurs being reptiles. It's just that the old-school taxonomists like Ernst Mayr disapproved of the little toothless feathered dinosaurs--birds--being lumped in there too.
But all the modern phylogenetic work I've seen classifies birds as reptiles without blinking an eye. Even the few systematists who think birds weren't dinosaurs generally consider them to have descended from some other reptile taxon, and therefore to be reptiles themselves.
Posted by: Anton Mates | February 13, 2007 6:27 PM
No no, a true cladist's nitpick would be to point out that there are three reptiles in the picture.
Posted by: windy | February 13, 2007 6:55 PM
In this picture, PZ looks like Peter Dodson, the certopsian expert. And. . dinos are every bit as reptilian as we are. Nobody even uses the term 'reptile' any more, except perhaps when talking about YECs.
Posted by: mothra | February 13, 2007 7:00 PM
That is not a "big" snake.
And Reptilia is a perfectly good clade as long as you include the feathered kind.
Posted by: CCP | February 13, 2007 7:02 PM
EXTRA EXTRA!!!
kansas reappeals stupid policies!
http://www.msnbc.msn.com/id/17132925/
How's that for a valentine's present? :P
Posted by: TAW | February 13, 2007 7:47 PM
No, you would have to include the fuzzy kind as well.
Posted by: Greco | February 13, 2007 7:57 PM
Ah, but won't the cephalopods be jealous? This is clearly vertebrate infidelity, after all....SH
Posted by: Scott Hatfield | February 13, 2007 8:05 PM
Somewhat related...
Anyone want to buy a mosasaur
The damnedest things show up on eBay.
Posted by: Graculus | February 13, 2007 8:25 PM
Cephalopod Love might be even more "brilliant" than reptilophilia.
Posted by: Michael Bains | February 13, 2007 8:49 PM
Exellent fashion statement - I might even start wearing ties again if they looked like that.
Posted by: John Berg | February 13, 2007 9:01 PM
I know this is off topic but can someone start a "How dumb is Davescott page". He's on UD trying to debunk global warming using Roy spencer sat temp data from 97. Even though Roy Spence himself has stated in public his data is wrong. I'd tell him at UD but I've been band. I'd set up the page myself if I wasn't lazy ;-)
Posted by: Kenny Gee | February 13, 2007 9:25 PM
Nope, the ancestors of mammals were never reptiles. The smallest clade containing both mammals and reptiles is Amniota. The amniotes split into the synapsids, containing us, and the reptiles.
See ToLWeb for a cladogram.
Posted by: Anton Mates | February 13, 2007 10:34 PM
Oop, forgot to include the ToLWeb link.
Posted by: Anton Mates | February 13, 2007 10:42 PM
Are those Silhouettes you are wearing? Wow, PZ and I have the same eyewear. Cool. Now all I need is the snake!!
Posted by: kmiers | February 13, 2007 11:21 PM
"Nope, the ancestors of mammals were never reptiles. The smallest clade containing both mammals and reptiles is Amniota. The amniotes split into the synapsids, containing us, and the reptiles.
See ToLWeb for a cladogram."
And Reptilomorpha is below Reptilia, which makes it include Synapsids as well...
All reptile was originally used for was to lump all cold-blooded amniotes together (and by this earlier definition, yes, pre-mammaliaformes were reptiles). Due to the fossil record, and comparative anatomy, the idea of a common source to all that would be "reptiles" falls apart. People have tried to save it in numerous ways, but in reality, it has lost its original meaning, and is basically a vestigial term now. We include things that we did not before, and excludes others in an attempt to save the term, but we basically fail...
In reality, fish, Bird and Mammal are not defined well either. Yes, just like with reptile, there is an attempt to define, but when one tries to nail these terms down, too many exceptions and disagreements occur.
Posted by: Lago | February 14, 2007 1:05 AM
The folks at the Discovery Institute would think that all that is missing in this photo is an apple. Speaking of them, they aren't happy about Kansas are they? John West (who?) whining about extremists. They don't have any idea that they are the extremists do they?
Posted by: Mena | February 14, 2007 1:16 AM
Bob
Posted by: Bob O'H | February 14, 2007 2:26 AM
I'm probably not the first to say this, but wouldn't a squid be more appropriate?
Posted by: Markk | February 14, 2007 3:18 AM
Ah, the Thulsa Doom look.
Posted by: Russell Blackford | February 14, 2007 3:52 AM
That looks like a very beautiful snake. Are there any pictures without a great hulking human in the way?
Posted by: SEF | February 14, 2007 4:14 AM
This is unrelated, but clearly important for all pharyngulites to see:
http://news.bbc.co.uk/2/hi/science/nature/6357005.stm
Posted by: Far Away | February 14, 2007 4:50 AM
Speaking of Valentines cards, has anyone found a good Hallmark atheist valentines card to send to Karen Hunter ?
Posted by: MartinC | February 14, 2007 5:07 AM
Forget reptiles, they are all FISH!
Posted by: nemo ramjet | February 14, 2007 5:59 AM
Not that it matters, but I'm pretty sure that's a ball python, not a boa.
Posted by: sgtbowe | February 14, 2007 8:50 AM
Yep! Ball python. And it's so cute and cuddly awwwww LOOK at the cute little ball python...
Posted by: mjfgates | February 14, 2007 11:46 AM
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Posted by: Jonathan Vos Post | February 14, 2007 1:44 PM
What a cutie!
(And you're looking pretty good yourself, P.Z.!)
Posted by: Julie Stahlhut | February 14, 2007 4:15 PM
True, but Reptilomorpha was never (AFAIK) considered equivalent or even similar to "reptiles." It started out as a category for reptile-shaped amphibians like labyrinthodonts, and has been expanded either to the labyrinthodont -frog clade, or the labyrinthodont +parrot clade.
Actually, there's a lot of work arguing that many of the "mammal-like reptiles" were at least moderately warm-blooded, as were the primitive archosaurs ancestral to crocodilians.
I would say the term, if it ever had any validity, couldn't depend on universally shared characteristics. The pre-cladistic "reptiles" referred to a cloud of properties, and even the most traditional reptiles each have only some of them. Reptiles have three-chambered hearts--except crocodiles don't. They don't take care of their young--except crocodiles do. They excrete uric acid--except turtles don't. They lay eggs--except seventy-odd lizard and snake species don't. The leatherback sea turtle may even be warm-blooded.
The only obvious thing that all traditional "reptiles" have, bar none, is scales--and birds have those too! So folding birds into "reptiles" doesn't do much to damage the term IMO.
That's definitely true of fish; there'll never be a clade which corresponds remotely to what English-speakers mean by the word. But birds and mammals are pretty straightforward. It's just a matter of how many extinct taxa you want to tuck into each group--plenty of grist for argument there among paleontologists, but nothing that would blow a layperson's mind more than the platypus already has.
Posted by: Anton Mates | February 14, 2007 6:38 PM
Lago said: (All reptile was originally used for was to lump all cold-blooded amniotes together (and by this earlier definition, yes, pre-mammaliaformes were reptiles).
Anton replies: Actually, there's a lot of work arguing that many of the "mammal-like reptiles" were at least moderately warm-blooded, as were the primitive archosaurs ancestral to crocodilians.
So what? Just because they used that as the definition does not mean I was agreeing with it by stating such. Being "cold-blooded" doesn't helps define what a reptile is or not. According to the phylogeny given by you, both warm and cold bloods are included, so that point is null and void relative to this discussion. Also, making this issue even more null is the fact that only some earlier synapsids were considered to have some type of elevated metabolic rate, why many others were considered not to have.
Simply put, arguing that some pre-mammaliaformes had an elevated rate does not in any way remove them from being defined as reptiles due to this you own reasoning with birds...
Lago said: Due to the fossil record, and comparative anatomy, the idea of a common source to all that would be "reptiles" falls apart. People have tried to save it in numerous ways, but in reality, it has lost its original meaning, and is basically a vestigial term now. We include things that we did not before, and excludes others in an attempt to save the term, but we basically fail...
Anton replies: I would say the term, if it ever had any validity, couldn't depend on universally shared characteristics.
Agreed, but that is how the term was derived in the first place. Any new cladistical meaning was developed after the fact in an attempt to save the term, which it can only do by destroying the original definition...
Anton continues: The pre-cladistic "reptiles" referred to a cloud of properties, and even the most traditional reptiles each have only some of them. Reptiles have three-chambered hearts--except crocodiles don't.
Which shows how the assumed traits were not applicable as I stated...
Anton again: They don't take care of their young--except crocodiles do.
Actually, I have seen land iguanas watch over their eggs as well and I would guess many others help their young in other ways...
Anton once more: They excrete uric acid--except turtles don't. They lay eggs--except seventy-odd lizard and snake species don't. The leatherback sea turtle may even be warm-blooded.
Again, showing, as I said, that the original definition has been gutted, and the surviving definition is only a modified one that contains no set traits. What they have basically done is found a node which they believe all animals that used to be defined generally as reptiles sprung from. To keep this node as a root to "reptilia", they either had to include birds (which is what they did) who were not originally placed under reptile, or exclude crocs, which they didn't want to do.
Anton claims: The only obvious thing that all traditional "reptiles" have, bar none, is scales--and birds have those too! So folding birds into "reptiles" doesn't do much to damage the term IMO.
Mammals, like opossums, also have scales, so include mammals on that list, oh, and apoda also have scales under the "amphibians" , so, scales are found in all modern tetrapod groups.. reptiles, birds, amphibians, as well as mammals. Basically put, using your reasoning of "folding" birds into reptiles by way of scales, makes all living tetrapods reptiles.
Lago said: In reality, fish, Bird and Mammal are not defined well either. Yes, just like with reptile, there is an attempt to define, but when one tries to nail these terms down, too many exceptions and disagreements occur.
Anton says: That's definitely true of fish; there'll never be a clade which corresponds remotely to what English-speakers mean by the word.
Agreed. Once internal gills were found in basal tetrapods like Acanthostega, "fish" fell completely apart forever...
Anton claims: But birds and mammals are pretty straightforward. It's just a matter of how many extinct taxa you want to tuck into each group--plenty of grist for argument there among paleontologists, but nothing that would blow a layperson's mind more than the platypus already has.
Mammal implies mammary glands, but the fossil record does not help us much with that. Due to this, we use osteological traits to define mammal. For some odd reason, we generally claim Morganucodontids even though the diagnostic trait of 3 inner ear bones does not work, as these elements are still associated with the lower jaw*. Since this is so, why don't we place Pachygenelius under mammaliaformes? Why not place Thrinaxodon under mammals as well? In short, the old definitions fall apart and clear lines are near impossible to draw unless one uses a tentative arbitrary pencil that is based more on personal opinion, than any real extrapolation of logic.
(*Monotremes are suspected by some to have derived their 3 inner ear bones on a separate evolutionary path, so using that trait does not imply a monophyletic grouping with all modern mammals)
For birds, if we cannot show that all volant theropods, such as Microraptors, Archaeopteryx etc... were derived from the same node, as well as the branches that lead to the modern extant birds, and that they were not derived from non-volant theropods separately, then "bird" falls apart. Since there is almost no way to assure everyone that flight was not derived more than once from different (even if closely related) theropod groups, then it becomes impossible to truly define "bird" in any phylogenic sense. It also falls apart using traits alone as most all "bird" traits are also found in theropod dinosaurs.
Posted by: Lago | February 15, 2007 3:57 AM
that's not what i would call a big reptile (the snake). i mean, my boas are a lot bigger than that little ball python at over 7 feet long each and 15ish and 20-something pounds, and i consider them to be small snakes.
Posted by: knobody | February 15, 2007 1:41 PM
I agree; I'm just saying it's not true that "by this earlier definition, yes, pre-mammaliaformes were reptiles". Even if you accept that definition of "reptile," a lot of the pre-mammaliaformes don't qualify. Perhaps you meant that, when that earlier definition was dominant, people thought the pre-mammaliaformes qualified?
That's precisely where I disagree. I don't think the term has been dependent on universally shared characteristics since well before cladistics was developed; see below.
Eggs, yes, but as far as I know only crocodilians protect them once hatched. I'd be interested to know of any exceptions.
But that "gutting" is not due to cladistics or paleontology, and much of it was done long ago--viviparous reptiles have been known for centuries, for instance. Yet the term continued to be widely used, generally without causing confusion, which makes it apparent that an exclusive, universally-shared characteristic wasn't necessary. Traditionally "reptiles" meant something like "snakes, lizards, turtles & crocs," animals which mostly had scales and cold blood and laid eggs and ignored their (hatched) young and couldn't breathe water and so forth--and if a particular "reptile" happened not to have some of those characteristics, that wasn't a problem so long as it was generally similar to other reptiles.
Now fold birds in there. What have you lost? Not much--cold blood and parental neglect are in the minority now, but they're still scaly airbreathers who mostly lay eggs and mostly excrete uric acid and mostly share various skeletal features and so forth. It's not dramatically less meaningful from a phenetic perspective, and now it actually has some evolutionary meaning.
Now if you're saying "reptiles" is just a fairly useless term no matter what, I'm not sure I'd disagree. I'm just saying it doesn't get more useless because now it's got birds in.
Bird/reptile scales are distinctly different from mammalian and amphibian scales in anatomy and composition, though. You could elaborate "scales" to something like "epidermal scales made mostly out of beta-keratins"--no one's going to confuse pangolins with reptiles on that score.
But for those of us who aren't paleontologists, who cares? It doesn't weaken our ability to classify any modern species--or any species of the last 70 million years or so--as "mammal" or "not mammal." It's not like the "fish" case, where there simply is no clade which will unite classic "fish" like sharks and trout while excluding classic "not fish" like us.
A category doesn't become useless simply because borderline cases exist.
There was an '05 paper on platypus nuclear genes (Rheede et al., in Molecular Biology & Evolution) that seemed to place monotremes pretty conclusively as the sister group to therians.
Well, no, it just means you should be defining "bird" cladistically instead of phenetically. If "bird" is the minimal clade starling+kiwi (I think that covers everything modern), then your definition doesn't depend on the fossil record in the first place. It may still be unclear whether flying dinosaur X was a true bird or not, but that's a matter of flying dinosaur X's classification and not of the definition of "bird" itself.
Posted by: Anton Mates | February 16, 2007 11:50 PM
Yes, of course, nobody doubts that anymore (as long as we only talk about the living) -- but now we have several fossils on the monotreme stem that seem to retain the middle ear bones in the lower jaw. Thus, the condition in monotremes and the condition of a large group that includes Theria* has probably arisen separately. Which is stunning, but so far there's no way to explain it away.
* The last common ancestor of placentals and marsupials, and all of its descendants.
Posted by: David Marjanović | February 17, 2007 8:30 AM
Anyone who wants to discuss the meaning of "Reptilia" should check out our poll and discussion at the ISPN's* forum: http://www.phylonames.org/forum/viewtopic.php?p=510
* International Society for Phylogenetic Nomenclature
Incidentally, the historical usage of "Reptilia" is not as consistent as some would like to think. Linnaeus included not only lizards, crocodiles (which he classified as lizards), snakes, turtles, etc. but amphibians and sharks (yes, sharks!) as well. (And that's ignoring his earlier usage of "Reptilia" for a group of worms!)
Posted by: Mike Keesey | April 14, 2007 11:41 AM