Mother of all squid!

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Blogging on Peer-Reviewed Research

Well, more like great-great-many-times-great-aunt of all squid, but it's still a spectacular fossil. Behold the Cambrian mollusc, Nectocaris pteryx.

nectocaris.jpeg
(Click for larger image)

Reconstruction of Nectocaris pteryx.

This was one of those confusing, uninterpretable Cambrian animals, represented by only one poorly preserved specimen. Now, 91 new specimens have been dug up and interpreted, and it makes sense to call it a cephalopod. It has two camera eyes — not arthropod-like compound eyes — on stalks, an axial cavity containing paired gills like the mantles of modern cephalopods, and a flexible siphon opening into that cavity. There are also subtle similarities in the structure of the connective tissue in the lateral fins. Obviously, it has a pair of tentacles; no mouthparts have been preserved, but there are hints in the form of dark deposits between the tentacles, which may be all that's left of the mouthparts — and are in the right place for a cephalopod ancestor.

There are still mysteries. There's no hint of a shell; previous theories had postulated a shelled common ancestor to squid, nautiloids, and ammonoids, but either this was a specialized branch that lost the shell, or modern cephalopod groups independently re-evolved the structure. It also has only two tentacles! Again, we don't know whether this was the ancestral condition, or whether Nectocaris is the product of a derived fusion. Known cephalopod Hox genes use a novel combinatorial scheme to encode arm identities, so I guess I wouldn't be too shocked if the eight- to ten-arm condition is a relatively recent (in geological terms!) innovation.

About that great-aunt remark…here's where their analysis places the Nectocarids, as a Cambrian side-branch of the group that led to the modern forms.

nectocaris_phylo.jpeg
(Click for larger image)

Phylogenetic position of the nectocaridids. Arrows indicate the crown groups of 1, molluscs; 2, conchifera; 3, cephalopods. Stars represent the earliest record of mineralization in each lineage. Clade divergence times (dotted lines) are unconstrained. Early branches follow previous phylogeny.

Note the dotted lines everywhere — those are lineages that we haven't found in the fossil record yet. Nectocaris is small (about 4cm long) and softbodied, and it required excellent preservation for any trace of them to survive. Specimens from the beginning of the Cambrian, representative of the groups indicated by the red arrows at 1 and 2, would be wonderful to have…but they're also going to be forms that wouldn't have been ideal for fossilization. Clearly, we need to fund more paleontology.

Ed Yong has more to say at Not Exactly Rocket Science.


Smith MR, Caron J-B (2010) Primitive soft-bodied cephalopods from the Cambrian. Nature http://dx.doi.org/10.1038/nature09068.

37 Comments

Oh, you just HAD to post that one, didn’t you PZM? Man, I can just FEEL the excitement off of that posting.

It is pretty impressive though. The natural science blogosphere is certain to play it up.

Wow!

There’s no hint of a shell; previous theories had postulated a shelled common ancestor to squid, nautiloids, and ammonoids, but either this was a specialized branch that lost the shell, or modern cephalopod groups independently re-evolved the structure.

Or this is a stem-cephalopod, and there is a single, shelled ancestor for crown cephalopods. At any rate, there is still the separate question of whether the common ancestor of all mollusks (or of was shelled).

And we still need to know where to put solenogastres and caudofoveates. Are they primitively unshelled? Hard skeletons have been evolved and lost many times, and this discovery just points out how biased the fossil record is. There are probably many sizable radiations of soft-bodied animals we know little or nothing about.

Well, that was a bit garbled. Try again: At any rate, there is still the separate question of whether the common ancestor of all mollusks (or of all shelled mollusks, at least) was shelled.

Only 2 tenticles thats not going to feed a family of 4 hominids. Please ignore time distortion and size relativity, it’s a joke. now sneer.

It sure would be nice to see some photos of the actual new fossils. The only photo of a fossil Nectocaris that I could find was in The Fossils of the Burgess Shale (Brigs, Erwin and Collier), and it still looks like an arthropod to me. Even the photo of the fossil in the Not Exactly Rocket Science link doesn’t (to my untrained eye) look molluscan to me. My other books on the Burgess Shale (It’s a Wonderful Life by Gould and The Crucible of Creation by Conway-Morris) are at work, so I’ll have to check them out tomorrow.

By the way, for those who haven’t done so, click on that NERS link - there’s also links to some other cephalopod articles that must make PZ’s heart go pitter pat. Among them is some fantastic video of a living Argonaut.

Oh, and by the way, I don’t mean to imply that the article by Smith and Caron are wrong, just that I don’t see the resemblance that much. I guess I’ll have to check out the actual Nature article.

Fascinating!

Does anyone have any photos of Nectocaris’ relative Petalilium?

The paper itself only has a couple more photos, but the supplementary info is loaded with ‘em.

Four centimeters? From the picture, I thought it was more like four meters. That must be a krill’s-eye view.

So it’s krill or be krilled?

Henry J said:

So it’s krill or be krilled?

OK, definitely fined on that one.

Just to add a YEC take correction. No need to see anything here but great diversity at a particular place and time. Its a snapshot of the moment when they were overwhealmed by sediment and turned into stone etc. They are not a trail of heritage and even the author notes things are different from what was expected. As usual. They always expect a family tres along the way of a evolution trail. Naw. jUst great diversity caught by the great flood of Noah. i insist this squid ish thing was alive while noah was. The geology is wrong and so is the biology. no intermediates forms will ever be found. all are types in kinds.

Robert Byers Wrote:

Just to add a YEC take correction.

Did you add your “YEC take correction” to Stephen Meyer’s OEC “explanation” of the origin of Cambrian phyla too? As you know, as wrong as he is about everything else, Meyer agrees with Myers that N. pteryx existed 500 MY ago, many MY before dinosaurs, which themselves were many MY before H. sapiens.

Frank J said:

Robert Byers Wrote:

Just to add a YEC take correction.

Did you add your “YEC take correction” to Stephen Meyer’s OEC “explanation” of the origin of Cambrian phyla too? As you know, as wrong as he is about everything else, Meyer agrees with Myers that N. pteryx existed 500 MY ago, many MY before dinosaurs, which themselves were many MY before H. sapiens.

Cranks and frauds like Robert Byers are seldom inclined to bash other cranks and frauds, because they all delude themselves into thinking there is something meritorious about attacking the “establishment”, whatever it is.

There is NO evidence for the world wide flood depicted in Genesis. If the fossil record resulted from that, there would be NO order to the fossils and we wouldn’t have the idea of a “Cambrian period” or any other.

Dale Husband Wrote:

Cranks and frauds like Robert Byers are seldom inclined to bash other cranks and frauds, because they all delude themselves into thinking there is something meritorious about attacking the “establishment”, whatever it is.

There is NO evidence for the world wide flood depicted in Genesis. If the fossil record resulted from that, there would be NO order to the fossils and we wouldn’t have the idea of a “Cambrian period” or any other.

Sure, but it’s fun to watch them slip up from time to time. Either they forget the mandatory “pseudoscience code of silence” and say things that contradict claims made by fellow evolution-deniers. Or sometimes even admit that they are covering up fatal differences that dash any hope for an alternate “theory.” Steve P. is one who does both - concedes old life and common descent, yet admits deliberately refusing to challenge anyone but “the king of the hill.”

Frank J -

I can’t help noticing that these two tendencies are always present in the denialists -

1) Alliance of convenience. Never, ever openly dispute other denialists, no matter how great the differences. An amusing example is FL, who rails against even the most devout Christian who accepts mainstream science, but has little to say about any form of evolution denial, however far from YEC it may seem to be.

2) Denial in every sense. Run hard and fast away from any actual discussion of actual science, even at high school or layman’s level. Hence, a thread like this gets relatively few comments - just one drive-by by Byers - because it includes some technical discussion.

I generally see two (not mutually exclusive) types of denialists. The majority are just motivated by political and social biases; they have been told that “their side” denies some uncomfortable scientific reality and respond with loyalty. As I’ve mentioned, for such people, “truth” seems to be defined as what you can force other people to agree to.

The other type are the insecure/narcissistic crackpots, who are obsessed with proving that they are “greater geniuses” than mainstream scientists. As I said, these categories are not mutually exclusive. Many prominent creationists, like Dembski, are both. Others are mainly one or the other. But the behaviors are the same.

harold said:

1) Alliance of convenience. Never, ever openly dispute other denialists, no matter how great the differences.

Undeniably true of course, but there’s also the amusing corrollary to said rule: “If somebody like [Enable javascript to see this email address.] [Enable javascript to see this email address.] DOES rock the boat, make sure he’s banned immediately.”

harold said:

The other type are the insecure/narcissistic crackpots, who are obsessed with proving that they are “greater geniuses” than mainstream scientists.

I did some writing on relativistic physics for my website and got to know the Einstein-bashers pretty well. They’re the classic example: “I’M smarter than EINSTEIN!” At least for those who don’t write pure incomprensible gibberish, they always make the same doofus errors. Incidentally, some are motivated by antisemitism and it’s obvious at a glance – “the JEW Einstein!” – but they are a small minority.

There are some secular creationists, or at least creationist sympathizers, who follow this pattern, who aren’t fundies. Of course, nobody has the slightest chance of going broke placing a bet that somebody talking the creationist line is a fundie. If it was just the secular creationists, they wouldn’t be any more troublesome than the Einstein-bashers are.

MrG -

You are describing the phenomenon exactly.

The only real difference between the fields is the ratio of the types. In physics denial, the narcissistic/insecure “great genius” crackpot is in the majority. In evolution denial (and also in HIV and climate change denial), the angry authoritarian follower propaganda shouter is in the majority. Although as I mentioned, many people are both.

Robert Byers said:

Just to add a YEC take correction. No need to see anything here but great diversity at a particular place and time. Its a snapshot of the moment when they were overwhealmed by sediment and turned into stone etc. They are not a trail of heritage and even the author notes things are different from what was expected. As usual. They always expect a family tres along the way of a evolution trail. Naw. jUst great diversity caught by the great flood of Noah. i insist this squid ish thing was alive while noah was. The geology is wrong and so is the biology. no intermediates forms will ever be found. all are types in kinds.

7.3

Moderate but sketchy flood justification.

Bonus point for “squi ish.”

The crown jewel is of course “i insist this squid ish thing was alive while noah was.”

Hmm… Byers’s insistence vs. all of modern science. Now, which should I go with…

Just Bob said:

The crown jewel is of course “i insist this squidish thing was alive while noah was.”

Leading to the immediate thought of how the Flood killed off an ocean creature – but such questions have been posed before, and there’s sure to have a reply that will leave people knowing less after they get the answer than they did before.

“Don’t ask.”

Leading to the immediate thought of how the Flood killed off an ocean creature

That’s not hard to figure out. Too hot (or too cold), too salty or not salty enough, too deep to reach the bottom, too much or not enough sunlight, not enough oxygen in the water, too much turbulence, no food because it all died, no nesting sites, no rivers to spawn in, etc.

If Byers sticks his fingers in his ears any harder, he’s likely to pith his brain.

oh, wait…

Oh no! A pithed off Byers!

(Sorry–couldn’t help myself.)

“Obsessed and touchy; imagined slight against transvestites triggered an eruption of nazi accusations. Desperately needs help from a mental health professional.”

Oh, aren’t we all.

I’ve got some very interesting information about Professor P Z Myers. Stuff that he doesn’t want anyone else to know about, and stuff that isn’t exactly pc.

Oh, please do share, Becky.

What a maroon.…

And wot now? You’re going to demand that PZM buy camera gear for you?

Becky said:

I’ve got some very interesting information about Professor P Z Myers. Stuff that he doesn’t want anyone else to know about, and stuff that isn’t exactly pc.

That you think PZ Myers is a mean Nazi simply because he holds pedophiles and their handlers in the Roman Catholic Church in utter contempt?

“That you think PZ Myers is a mean Nazi simply because he holds pedophiles and their handlers in the Roman Catholic Church in utter contempt?”

No.

Becky said:

“That you think PZ Myers is a mean Nazi simply because he holds pedophiles and their handlers in the Roman Catholic Church in utter contempt?”

No.

So, do you actually have anything to say that’s worth reading? Or are you just here to play stupid guessing games? You’ve had days to post this amazing secret information you claim to have, but you haven’t done so. That, to me, looks like you’ve got nothing.

Hi phantomreader42: Big apologies for the delay, but I will provide a link here to the information by next Tuesday at the latest.

Becky

Oh, no rush. Any time is fine.

PZ Myers is not a tactful, moderate, or tolerant person, and he doesn’t want to be one.

But he seems to have a real ability to bring enemies out of the woodwork that make him look good in comparison.

That’s it? That’s your “Stuff that he doesn’t want anyone else to know about, and stuff that isn’t exactly pc,” a public comment I made, plus your weird paranoid spin?

You really are a nut.

Becky Transsexual said:

Here it is:)

http://beckytranssexual.wordpress.c[…]the-skeptic/

Wow. You came in here crowing about some amazing secret information you claimed to have, babbling about some big secret of PZ’s that you were going to expose. You did so by reviving a dead thread that had nothing to do with your gripes, but people were curious enough to ask you what the fuck you were talking about. But when you were called upon to actually POST this world-shaking revelation you claimed to have, you disappeared for two weeks without a word. Then you came back to drop an insincere “apology” for the delay. Then, finally, over a MONTH after your initial bit of thread necromancy, you posted your stunning expose: a link to your blog, quoting something PZ said publicly on his own blog over a month ago. Nothing hidden, nothing secret, nothing new except your own paranoid delusional babbling and spin. You didn’t even have the common courtesy to post your bullshit whines here, where you bragged about them in the first place.

You’re a disappointment, Becky. A total failure. You could’ve at least made up something amusing. Instead you just wasted everyone’s time pretending you had something special to share, only to abuse a dead thread to blogwhore your paranoid ramblings about month-old publicly-posted comments.

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This page contains a single entry by PZ Myers published on May 26, 2010 3:33 PM.

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