Magnificent momma

| 68 Comments

This is one beautiful plesiosaur, Polycotylus latippinus.

Polycotylus.jpeg
(Click for larger image)

(A) Photograph and (B) interpretive drawing of LACM 129639, as mounted. Adult elements are light brown, embryonic material is dark brown, and reconstructed bones are white. lc indicates left coracoid; lf, left femur; lh, left humerus; li, left ischium; lp, left pubis; rc, right coracoid; rf, right femur; rh, right humerus; ri, right ischium; and rp, right pubis.

The unique aspect of this specimen is that it's the only pregnant plesiosaur found; the fore and hind limbs bracket a jumble of bones from a juvenile or embryonic Polycotylus. It's thought to actually be a fetal plesiosaur, rather than an overstuffed cannibal plesiosaur, because 1) the smaller skeleton is still partially articulated, and it's large enough that it is unlikely it could have been swallowed whole, 2) the two sets are of the same distinctive species, 3) the juvenile is incompletely ossified and doesn't resemble a post-partum animal, 4) the bones aren't chewed, etched by acids, or accompanied by gastroliths. I think we can now confidently say that plesiosaurs were viviparous, which is what everyone expected.

There are other surprising details. The fetus is huge relative to the parent, and there's only one — so plesiosaurs had small brood sizes and invested heavily in their offspring.

polycotylus_rec.jpeg
(Click for larger image)

Reconstructions of female P. latippinus and newborn young. Gastralia were present in both animals but have been omitted for clarity.

The authors speculate beyond this a bit, but it's all reasonable speculation. That degree of parental investment in fetal development makes it likely that there would have been extended maternal care after birth, and rather more tenuously, that they may also have lived in larger social groups. The authors suggest that their lifestyle may have resembled that of modern social marine mammals — picture a pod of dolphins, only long-necked and lizardy.


O'Keefe FR, Chiappe LM (2011) Viviparity and K-Selected Life History in a Mesozoic Marine Plesiosaur (Reptilia, Sauropterygia) Science 333 (6044): 870-873.

(Also on FtB)

68 Comments

There seems to be an increasing tendency to find evidence of behavior, in large but small-brained vertebrates of the Mesozoic, that resembles the behavior of large and large-brained modern vertebrates.

If this is correct, the very strong relationship between cephalization and behavioral repertoire that we see in the modern era (mainly with total brain size although in small animals, brain mass to body mass ratio may be relevant) may not have been as strong.

If these types of animals did have behaviors that are mainly associated with highly cephalized lineages in the modern world, I can’t help wondering if there is something about their neurobiology that we don’t, and may never, understand.

This comment has been moved to The Bathroom Wall.

Atheistoclast said: But no amount of mutations in hox genes will account for the degree of physiological synpolydactyly observed here.

So what alternative do you propose? They were created that way?

Paul Burnett said:

Atheistoclast said: But no amount of mutations in hox genes will account for the degree of physiological synpolydactyly observed here.

So what alternative do you propose? They were created that way?

What I’d like to know, Paul, is how Atheistoclast defends this pronouncement (which is OT, incidentally). IANADB (developmental biologist) but there are several in the PT community who are. Atheistoclast, how do you know what hox genes are and are not capable of? Every organism on the planet with a body expresses hox genes, as you well know, so why do you find this plesiosaur’s limb structure unlikely (especially given the incredible diversity of bodies)? Please convince us that you didn’t just copy-and-paste your post.

If these types of animals did have behaviors that are mainly associated with highly cephalized lineages in the modern world, I can’t help wondering if there is something about their neurobiology that we don’t, and may never, understand

On the other hand, I think I will correct myself here. My childhood exposure to dinosaur science happened to take place about the time that “encephalization quotient” (ratio of brain size to body size) was in vogue; I probably absorbed stereotypes. However, 1) modern animal behavior actually correlates better with overall brain size/body temperature regulation, and 2) Dinosaur-age large vertebrate brains were not all that small.

I remember the “size of a walnut” stereotype; in fact, there are probably primate species with brains the size of a walnut. (The quote below deals with dinosaur brains; I realize that the thread doesn’t deal with a dinosaur, but it is still germane.)

“It is often said that Stegosaurus had a brain the size of a walnut - in fact it was more like the size of a lime, or a dog’s brain, but still relatively small for a dinosaur that grew up to nine metres long.” http://www.guardian.co.uk/science/2[…]e-brain-size

So in fact, relatively developed behavior may not be surprising at all.

Joe Bozorgmehr -

Please deal with Paul Burnett’s question first. Then…

But no amount of mutations in hox genes will account for the degree of physiological synpolydactyly observed here.

Putting aside whether this blank assertion is true or not, why are you arguing against a sraw man? Did anyone say vertebrate digit morphology is exclusively controlled by Hox genes?

How long ago did the dinosaurs live? If you don’t agree with the scientific consensus on this, exactly what alternative do you propose?

Atheistoclast said: But no amount of mutations in hox genes will account for the degree of physiological synpolydactyly observed here.

Two things: 1. Argument from bare assertion. 2. Has the claim you think you are addressing even been made or are you simply attacking a straw-man you just set up?

I expect references when/if you try to answer. As in, a peer-reviewed paper detailing an actual laboratory experiment that directly supports your blunt assertion above(the specific claim that no amount of mutations in hox genes will produced the observed degree of change), and another reference for the implied claim you are addressing: Someone(actual developmental biologist) directly making the claim that pure mutations to hox genes does account for the observed degree of change.

Testable prediction 1: None of what I just asked for will be forthcoming from Atheistoclast. Testable prediction 2: Lots of obfuscation and barely, tangentially relevant walls of text and quote-mines will be produced instead, in an obvious attempt at obfuscation.

I should also add, what degree of change are we even talking about? From what to what? This hasn’t even been specified so without this, the claim Atheistoclast makes and attacks is not only unsupported, but meaningless.

Of course, developmental pathways are necessary and sufficient to produce the limbs of all vertebrates. And changes in the pathways, particularly those that affect gene regulation, are demonstrably responsible for producing the diversity of vertebrate limbs that are observed. Indeed, it is literally impossible to explain vertebrate limb evolution outside the context that these pathways and consideration of the mechanisms by which they change over time. Here is a good review article containing seventy three references:

Woltering and Duboule (2010) The origin of digits: Expression patterns versus regulatory mechanisms. Developmental Cell !8:526-532.

Now of course no one has to believe it. They are perfectly free to no believe it, regardless of the fact that they have no evidence to the contrary, regardless of the fact that they have no explanation for the available evidence and regardless of the fact that they have no viable alternative. But then again, everyone is perfectly free to ignore those people as well.

But no amount of mutations in hox genes will account for the degree of physiological synpolydactyly observed here.

IANAS, but please tell me why? Until a viable alternative “account for the degree of physiological synpolydactyly observed” is presented I am left with no alternative but to enjoy being

perfectly free to ignore those people as well.

Actually, we also know a lot about changes in hox gene regulatory regions and the evolution of flippers, Here is a good reference on the subject:

Wang et; al. (2009) Adaptive evolution of 5’ Hoxd genes in the origin and diversification of the cetacean flipper. Molecular Biology and Evolution 26(3):613-622.

It is pretty safe to assume that if changes in hox regulatory sequences could produce the diversity of flippers seen in cetaceans, that similar changes would be responsible for the evolution of plesiosaurs flippers as well. Obviously this isn’t the whole story and there is much more to be learned but it does explain a lot.

This comment has been moved to The Bathroom Wall.

Joe has apparently never read “Eight Little Piggies”.

Or anything else with scientific merti.

This comment has been moved to The Bathroom Wall.

Rumraket said:

Atheistoclast said: But no amount of mutations in hox genes will account for the degree of physiological synpolydactyly observed here.

Two things: 1. Argument from bare assertion. 2. Has the claim you think you are addressing even been made or are you simply attacking a straw-man you just set up?

I expect references when/if you try to answer. As in, a peer-reviewed paper detailing an actual laboratory experiment that directly supports your blunt assertion above(the specific claim that no amount of mutations in hox genes will produced the observed degree of change), and another reference for the implied claim you are addressing: Someone(actual developmental biologist) directly making the claim that pure mutations to hox genes does account for the observed degree of change.

Testable prediction 1: None of what I just asked for will be forthcoming from Atheistoclast. Testable prediction 2: Lots of obfuscation and barely, tangentially relevant walls of text and quote-mines will be produced instead, in an obvious attempt at obfuscation.

Atheistoclast’s last comment, which was moved to the BW (I’m not sure why) contains references to three papers he has published. The abstracts indicate that he uses the same modus operandi there as here: he cherry picks data to suit his purposes, and makes arguments from ignorance and personal incredulity.

IBelieveInGod said:

Looks like PZ Myers is a little touchy!

Prof Myers, you should return IBelieveInGod to the Bathroom Wall, too. He does not have posting privileges in threads other than the Bathroom Wall.

Wow, it looks like the special effects team went all out for this one. I think this thing started with parts from the set of Jurassic Park III, right Mr. Myers. Now, I think I will find some old props from werewolf and godzilla movies and I will have the perfect transitional form which will make me famous!

Why do you think finding a transitional would make you famous, lambchop? At last count in fossil forms alone, you’d have to take a ticket and join the queue, about 200 places down.

Dave Luckett said:

Why do you think finding a transitional would make you famous, lambchop? At last count in fossil forms alone, you’d have to take a ticket and join the queue, about 200 places down.

Yeah, I guess there are plenty of fossil hobbyists with basements and tools worldwide.

Not worldwide. Most of them seem to come from Texas, around Glen Rose and Mount Blanco.

The fossils were planted by UFOs … disguised as airliners … spreading Chemtrails™ … to make people crazy … and post silly trolls on internet forums.

DS -

Incidentally, I’m sure no-one here is disputing the major role of Hox genes in morphogenesis.

However, it is probably a straw man to suggest that anyone has ever yet claimed that Hox gene diversity, and only Hox gene diversity, accounts for all limb diversity in vertebrates.

Maybe Hox gene diversity is sufficient as a the genetic mechanism of limb diversity, but maybe not. What we know now is that it is important for limb morphology and has major effects on limb morphology.

The point of setting up that straw man is that the creationist using it will then be able to “claim victory” if any limb morphology variation is ever found to have anything to do with anything other than Hox gene variability.

Creationists commonly use this type of logic - trying to distort a positive scientific claim falsely into an exclusive claim, and then claiming that a violation of their own straw man exclusivity overturns a scientific principle. Scientists say that oranges are a source of vitamin C; creationists do the equivalent of arguing that scientists said “only oranges are a source of vitamin C”, or that “vitamin C is the only vitamin”, and claim that science has been overturned because grapefruit is also a source of vitamin C. And of course, it was scientists who also made the discovery of vitamin C in grapefruit.

Harold,

You are absolutely right. That’s why I was so careful to say that the hox gene sequence is not the whole story. That’s why I pointed out that more needs to be learned. Joe is the one who claimed that the authors concluded that this one change was sufficient to produce a flipper. They did not. Indeed, other changes in hox cis regulatory sequences are also known.

The point is that changes in hox genes and their regulatory sequences have been important is the evolution of the diversity of vertebrate appendages. This fact is indisputable, although that won’t stop some people from complaining about it. If those people claim that this is insufficient, the burden of proof is on them to demonstrate what more is needed. This does not prove that such changes were responsible for the evolution of plesiosaurs, it just makes it extremely likely. Now if anyone wants to falsify that hypothesis, all they need to do is to sequence some plesiosaur DNA, or at least provide some evidence that evolution works in fundamentally different ways in this lineage than in any other group of animals. Until then, claiming that every published paper is wrong is just nuts. Of course there is more to it than just one small change in one small gene. That doesn’t mean that science is wrong. it just means that more science is needed.

I’m not big on censorship, but a better permanent forum for the sheephumper would be the BW. He never adds anything, not even an honest misconception, question about evolution, or “how does evolution answer this creationist objection?” He just sneeringly accuses all scientists of blatantly lying about everything, always. We don’t need him. Let him yell in the toilet. The echoes are better in there, anyway.

harold said:

DS -

Incidentally, I’m sure no-one here is disputing the major role of Hox genes in morphogenesis.

However, it is probably a straw man to suggest that anyone has ever yet claimed that Hox gene diversity, and only Hox gene diversity, accounts for all limb diversity in vertebrates.

Maybe Hox gene diversity is sufficient as a the genetic mechanism of limb diversity, but maybe not. What we know now is that it is important for limb morphology and has major effects on limb morphology.

The point of setting up that straw man is that the creationist using it will then be able to “claim victory” if any limb morphology variation is ever found to have anything to do with anything other than Hox gene variability.

Creationists commonly use this type of logic - trying to distort a positive scientific claim falsely into an exclusive claim, and then claiming that a violation of their own straw man exclusivity overturns a scientific principle. Scientists say that oranges are a source of vitamin C; creationists do the equivalent of arguing that scientists said “only oranges are a source of vitamin C”, or that “vitamin C is the only vitamin”, and claim that science has been overturned because grapefruit is also a source of vitamin C. And of course, it was scientists who also made the discovery of vitamin C in grapefruit.

This is exactly what Atheistoclast does in the papers he referenced. In one case, he addresses gene duplication as a means of adding information to a genome. He talks about “well-known” examples and asserts that each case is inadequate to explain X. Even taking this at face value, what about the examples of gene duplication he DOESN’T discuss?

Further, in another paper he talks about gene duplication in the KPNA protein family. He states that some duplications become inactive, and some go on to acquire novel functions. He THEN goes on to say that this may not always be true. It may not ALWAYS be true that SOME do not go on to acquire novel functions?? That statement doesn’t even make sense!

DS -

We entirely agree, of course.

Just Bob -

While I agree that an “auto-BW” feature (certain usernames automatically sent there) would be great, I actually think that Joseph “Atheistoclast” Bozorghmer often, ironically, sets up some decent discussions.

On the other hand, a program that sends his third and subsequent comments on any thread to the BW would be handy :).

harold said:

While I agree that an “auto-BW” feature (certain usernames automatically sent there) would be great, I actually think that Joseph “Atheistoclast” Bozorghmer often, ironically, sets up some decent discussions.

On the other hand, a program that sends his third and subsequent comments on any thread to the BW would be handy :).

Maybe we need a “Galileo filter” that automatically sends posts claiming oppression by the Evil Darwinian Orthodoxy™ to the BW.

harold said:

Just Bob -

While I agree that an “auto-BW” feature (certain usernames automatically sent there) would be great, I actually think that Joseph “Atheistoclast” Bozorghmer often, ironically, sets up some decent discussions.

On the other hand, a program that sends his third and subsequent comments on any thread to the BW would be handy :).

I was referring to “Jumbuck”, who is a Poe anyway.

harold said:

If these types of animals did have behaviors that are mainly associated with highly cephalized lineages in the modern world, I can’t help wondering if there is something about their neurobiology that we don’t, and may never, understand

On the other hand, I think I will correct myself here. My childhood exposure to dinosaur science happened to take place about the time that “encephalization quotient” (ratio of brain size to body size) was in vogue; I probably absorbed stereotypes. However, 1) modern animal behavior actually correlates better with overall brain size/body temperature regulation, and 2) Dinosaur-age large vertebrate brains were not all that small.

I remember the “size of a walnut” stereotype; in fact, there are probably primate species with brains the size of a walnut. (The quote below deals with dinosaur brains; I realize that the thread doesn’t deal with a dinosaur, but it is still germane.)

“It is often said that Stegosaurus had a brain the size of a walnut - in fact it was more like the size of a lime, or a dog’s brain, but still relatively small for a dinosaur that grew up to nine metres long.” http://www.guardian.co.uk/science/2[…]e-brain-size

So in fact, relatively developed behavior may not be surprising at all.

Harold - below is not a critisism of your post - it my $.02 in addition:

I suspect that we cannot assume that sophisticated behavior/”intelligence” is exclusive of large brain size. Modern dinosaurs (birds) display a range of sophisticated behaviors , yet have small brains - see ALEX the grey parrot.

http://en.wikipedia.org/wiki/Alex_(parrot)

I don’t know what the “encephalization quotient” for a grey parrot is, but his brain was in the “walnut” range yet, despite this his “intelligence” was reported to rival some primates (or even dolphins!)

IMHO it is not a stretch at all to hypotosize some level of sophisticated behavior in Alex’s ancestors

https://me.yahoo.com/a/XRnHyQl8usUn[…]_GLu.k#d404b said:

harold said:

If these types of animals did have behaviors that are mainly associated with highly cephalized lineages in the modern world, I can’t help wondering if there is something about their neurobiology that we don’t, and may never, understand

On the other hand, I think I will correct myself here. My childhood exposure to dinosaur science happened to take place about the time that “encephalization quotient” (ratio of brain size to body size) was in vogue; I probably absorbed stereotypes. However, 1) modern animal behavior actually correlates better with overall brain size/body temperature regulation, and 2) Dinosaur-age large vertebrate brains were not all that small.

I remember the “size of a walnut” stereotype; in fact, there are probably primate species with brains the size of a walnut. (The quote below deals with dinosaur brains; I realize that the thread doesn’t deal with a dinosaur, but it is still germane.)

“It is often said that Stegosaurus had a brain the size of a walnut - in fact it was more like the size of a lime, or a dog’s brain, but still relatively small for a dinosaur that grew up to nine metres long.” http://www.guardian.co.uk/science/2[…]e-brain-size

So in fact, relatively developed behavior may not be surprising at all.

Harold - below is not a critisism of your post - it my $.02 in addition:

I suspect that we cannot assume that sophisticated behavior/”intelligence” is exclusive of large brain size. Modern dinosaurs (birds) display a range of sophisticated behaviors , yet have small brains - see ALEX the grey parrot.

http://en.wikipedia.org/wiki/Alex_(parrot)

I don’t know what the “encephalization quotient” for a grey parrot is, but his brain was in the “walnut” range yet, despite this his “intelligence” was reported to rival some primates (or even dolphins!)

IMHO it is not a stretch at all to hypotosize some level of sophisticated behavior in Alex’s ancestors

Feel free to criticize my posts any time :).

Funny that walnuts are so often used to describe brain sizes. I guess it’s because they look a little bit like brains. I wonder if they mean volume or mass, or whether that in or out of the shell.

Anyway, here’s my take -

1) Clearly, the relationship between brain anatomy and behavioral repertoire/learning ability is complex. Brain size is not the only issue.

2) Brain size to body size was once considered very relevant, but that linear relationship may not be such a big deal. The shrew has the highest.

3) Walnut sized brains are not all that small. In fact, relative to the overall biomass, that is a pretty big brain.

4) It is of great interest to note that birds, who are more closely related to dinosaurs than other current lineages (arguably are dinosaurs) have examples of high learning ability/behavioral flexibility with smaller brains…

Not all investigators are happy with the amount of attention that has been paid to brain size. Roth and Dicke, for example, have argued that factors other than size are more highly correlated with intelligence, such as the number of cortical neurons and the speed of their connections.[9] Moreover they point out that intelligence depends not just on the amount of brain tissue, but on the details of how it is structured. It is also well known that crows, ravens, and African Grey Parrots are quite intelligent even though they have small brains.

From - http://en.wikipedia.org/wiki/Brain_size End blockquote

5) And of course, octopuses show all sorts of learning and behavioral flexibility. They are cold blooded and lack the kind of myelin that vertebrates have.

6) Social insects show coordinated behavior and have stereotyped learning abilities, with individually tiny brains, but don’t show much flexibility, or wide-ranging learning ability (even fruit flies have some learning ability).

All in all, the relationship between brain characteristics and behavior is fascinating, and there is a lot left to learn, especially about non-mammalian lineages.

To return more or less to the topic (even if only as a tourist), I have often wondered what swimming style a beast with four paddles might adopt.

With the right skeletal rigidity, moving diagonally opposite paddle pairs in the same direction (e.g. LF, RR up; RF, LR down) could be seriously competitive. With the right musculature, you could even have significant power in reverse.

Mike Elzinga said:

Radioactive decay is very nearly ideal because even very energetic decays can produce cascades of energy such that there will be many energy windows within which complex systems can grow and survive. There will very likely be energies on the order of a few eV that can influence chemistry and energies on the order of a few hundredths of an eV that will provide a suitable thermal bath.

*I hate pressing the wrong button*

You mean like how various fungi at Chernobyl now use gamma radiation to convert melanin into energy?

mrg said:

Even if we search for them and come up zeroes, we’re bound to find some very interesting things in the meantime.

Even the replacements for these mysterious alleged other-lifeforms are extremely interesting, themselves. Like the various extremophile Archaeans like Halobacterium and Pyrococcus

mrg said:

Matt G said: I’m not so sure about that. A species of bacteria has been found which obtains its energy from radioactive decay.

COOL! Got a reference? Preferably one for layfolk.

One of the (admittedly emotional) arguments for abiogenesis is the extraordinary persistence of life – it’s like it seems driven to always find a way. Of course if it doesn’t … it’s not there any more.

Like this one?

http://web.archive.org/web/20080424[…]526/fob5.asp

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Mike Elzinga said:

Finding how life began is not just a matter of finding the “right” recipe; there may indeed be many recipes. Different life forms could be forming and evolving right here on Earth; they just might happen to be in places we haven’t gone yet. Lots of exciting science ahead.

Wouldn’t it be exciting to find life based on something other than DNA? RNA, perhaps, or a modified form of DNA (e.g., different bases), or something altogether different?

Such as something silicon based instead of carbon based?

Henry J said:

Such as something silicon based instead of carbon based?

I would find lifeforms that use enatiomers of DNA bases to be exciting, even.

apokryltaros said:

Henry J said:

Such as something silicon based instead of carbon based?

I would find lifeforms that use enatiomers of DNA bases to be exciting, even.

Dr. Edward Teller and Dr. Edward enantiomer-Teller.

apokryltaros said:

Henry J said:

Such as something silicon based instead of carbon based?

I would find lifeforms that use enatiomers of DNA bases to be exciting, even.

Or right-handed amino acids.

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