New Developments, New Dinosaurs, and a New Blog!

Posted by Nima On Wednesday, February 24, 2010 22 comments

Hello again dino-fans! I apologize for the long delay in getting stuff posted here, I have been working through a lot of projects, and mainly paleo-related ones.

There are several sauropods I have under completion and a radical and grand new skeletal (I dare not name the species, as I want to be the first to do a decent skeletal of it). And then there is the therizinosaur project from ArtEvolved, which I very much want to finish and submit, even if it's late. But the fascination with sauropods refuses to die! They are the frontier of paleontology that seems to defy frontiers altogether - seemingly getting larger, heavier, and stranger with each new discovery. And when you think you really know them, they get even stranger...

And there's another big piece of news (well, big to me at least). Nikola Popovic, a fellow paleo-fan, artist, blogger, and one of the most intelligent young science enthusiasts I've ever come across, has launched a new blog, which will include dinosaurs, space, evolution, the possibilities of life on other planets in distant star systems, and razor-sharp refutations of pseudoscience, from creationism to crypto-zoology. And even though Nikola's blog is still in its infancy, I thought I'd at least bring it to everyone's attention. Go visit it, and offer your comments and suggestions!

UPDATE:



Here's a NEW piece of paleo-news that Zach Armstrong brought to my attention: the mysterious new Cretaceous brachiosaur skull from Utah's Dinosaur National Monument (shown above), which I suspected to be from Cedarosaurus last year, has actually been described as a totally new genus and species: Abydosaurus mcintoshi.

Here's a brief video of the new discovery; as you can see, Michael Skrepnick has already painted a pretty nice restoration of the creature. What's more, he put the nostrils right where they belong - directly on the nasal chamber. Whether or not he's ever read my thoughts on the subject (roughly fifty gazillion posts and comments ago), I do feel at least a little bit vindicated :)


Interestingly enough, the team from BYU found skulls from four individuals packed into a fairly small area. Even though most of the remains found at the dig site are from 35-foot juveniles, there are some larger bones found along with them that likely belonged to adults, which would have measured roughly 70-80 feet long, the same average size range as Brachiosaurus altithorax. It's not too hard to imagine that Abydosaurus may have evolved directly from Brachiosaurus, which lived in the same general area millions of years earlier. The fossils are probably remains of a herd of these animals which all drowned together in a huge flood and were buried in sand and silt instantly. The sandstone surrounding the bones was incredibly dense and hard and precisely placed explosives were needed to loosen up the rock to get at the bones without damaging them - earning this new giant the nickname "the dynamite sauropod".

The really cool thing about these skulls, IMO, is that they seem to contain all the thin bony membranes inside the skull which usually get lost or destroyed, including the cranium, internal struts, and possibly delicate palate bones as well. Oh, and the hyoid (tongue bone) is also preserved! These skulls can literally tell us more about brachiosaurs than every skull found in the past hundred years. There's more info on this guy in the FREE description paper, here.

And guess what!? Soon I will upload my first blog entry for the new titanosaur art series: FORGOTTEN GIANTS. And believe me, what you will see in this series, will be unlike anything you've seen before.



Stay tuned....
.

22 comments:

Zach Armstrong said...

I will say it has been a grueling two months waiting for those titanosaurs, Nima, because man am I looking forward to them! Glad to see you haven't fallen off the face of the earth.

In case you haven't heard, the skull that you thought might be of Cedarosaurus is now the type specimen of a new genus of brachiosaur, Abydosaurus mcintoshi, and the paper is free!!

Nima said...

Woo hoo!!! I knew that skull would, to paraphrase Mozart, make a noise in the world some day!

I can't find the paper with google though, where's the link?

In any case, I'll post up the video of this amazing discovery.

The first couple of titanosaurs are almost ready, all that's left is a bit of digital juxtaposition.

Zach Armstrong said...

Oops, sorry, I forgot to post the link. The link to the paper is here. There is also quite a bit of supplementary material too, but sadly no full skeletal of the whole animal. There is a nice partial skeletal of the skull and the first four cervical vertebrae, though.

The full citation is:

Chure, Dan, Britt, Brooks B., Whitlock, John A., and Wilson, Jeffrey A. "First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition." Naturwissenschaften. Wednesday, February 24, 2010.

And I can't wait for those first titanosaurs!

Nima said...

Thanx, Zach! I'll post the link to the paper too, for those that don't bother to read the comments.

Ian said...

I'll admit I'm normally not that much of a sauropod guy, but this discovery is pretty cool. BTW, Nima, why do you think sauropods had their nostrils on the tops of their heads? I thought that idea had been discredited.

Nima said...

Actually, it has NEVER been discredited. Recently Dr. Larry Witmer proposed an ALTERNATE THEORY that basically places ALL dinosaur nostrils (not just sauropod ones) at the tip of the snout, barely above the lips. But his theory does NOT discredit ANYTHING. It's actually very problematic even to argue in favor of such a theory.

The problem is that he bases this on the facial musculature of modern mammals, whose skulls don't resemble dinosaurs much at all. They are certainly nothing like sauropod skulls.

Witmer's argument is this: All modern land animals have nostrils at the tip of the snout, hence sauropods did too.

My counter-argument: all living diapsids (especially Dinosaurs' closest living relatives, crocodiles and birds) have fleshy nostrils directly on top of their bony nostrils - no crazy nasal tubes separating the two like in elephants and whales. Therefore, it would make the most logical sense to put sauropods' fleshy nostrils directly over their bony nostrils - which means putting them on the FOREHEAD.

Furthermore, compare the well-defined bony nasal structure of sauropods to the big mammals that Witmer references (with all those thin sheets of bone that just wisp away into cartilaginous nothingness), and you realize they have almost NOTHING in common. Big fleshy nasal tubes just don't fit with the skull designs of any sauropods. The bones of the skull roof don't show any conclusive evidence of long nasal tubes having been there. No scars, no grooves, no real proof.

Also, Witmer's snout-tip-lip nostril configuration would be highly maladaptive and painful for any animal that spent the day sticking its snout into prickly conifer trees to feed. The nostrils were in a far safer position on the forehead - which is probably why the bony nostrils shifted there early in sauropod evolution in the first place.

Now to be fair, more recently Witmer has done a lot of good work on dinosaur skull pneumaticity, ear and brain structure, and the nasal passages of theropods (which are not all that controversial). He's undoubtedly a very accomplished scientist, but that said, his work on sauropod noses simply doesn't stand up to scrutiny.

Just to put things in perspective, normally I would not place brachiosaur nostrils at the very top of the nasal crest either - I would place them closer to mid-level on the crest, as Michael Skrepnick did... maybe just a bit higher.

Zach Armstrong said...

Actually, Nima, I think you missed the mark in your (albeit, brief) critique of Witmer's paper. I assume you are referring to the paper "Nostril Position in Dinosaurs and Other Vertebrates and Its Significance for Nasal Function." Lawrence Witmer et al. Science 293, 850 (2001).DOI: 10.1126/science.1062681.

It should be noted that Witmer's exact hypothesis was this: inferring from extant amniotes, dinosaurs had their nostrils rostrally located in their nares because almost all living amniotes have their nostrils rostrally located, i.e., the openings of the nostrils were located towards the front of the the nares. There is no mention in the paper of big fleshy nasal tubes by Witmer et al. as you assert, simply that the nasal openings were rostrally located.

As far as I know, reconstructions such as those by Luis Rey and others that show prominent nasal tubes have never been endorsed by Witmer in a technical paper, and thus are speculative (although not impossible).

Also your argument that nostrils being located at the tip of the snout would be maladaptive and painful is contradicted by living animals that have their nostrils rostrally located at the tip of their snouts: look at giraffes, for instance, they have fleshy nostrils located rostrally, at the tip of their skull and yet often feed on prickly vegetation such as Acacia species which have large thorns.

It should be noted that in the life reconstruction above of Abydosaurus the nostrils are rostrally located in the nares, although not to the extent that Witmer et al. suggests, and probably could be postioned further rostrally.

Nima said...

Well, since you quote this from Witmer:

"inferring from extant amniotes, dinosaurs had their nostrils rostrally located in their nares because almost all living amniotes have their nostrils rostrally located, i.e., the openings of the nostrils were located towards the front of the the nares."

Then if that's as far as he ventures to go, then even by Witmer's conclusion the nostrils should NOT be at the tip of the snout! "Rostrally located IN their nares" means, in plain English, that the fleshy nostrils are towards the FRONT of the bony nostrils, but still IN the bony nostrils (i.e. not beyond their margins).

If I were to take that view, then Skrepnick's painting (and any restoration that puts the nostrils near the front margin of the bony nares) is VALID! And there is no basis for placing them at the snout tip.

But somehow I doubt this was Witmer was trying to say. From what I recall, his paper has a Giraffatitan skull diagram which suggests that the "best" position for the nostrils was at the tip of the snout. This is not even NEAR the nares, let alone "rostrally located IN the nares". If your quote is accurate, then Witmer contradicted himself. Of course, that's a big assumption. I think Witmer was actually quite consistent in that paper, but also consistently wrong. Also, Luis Rey's stuff is his own interpretation of Witmer's theory. Witmer himself didn't invent the big gawky nasal tubes, but to place nostrils at the tip as he has proposed, would require nasal tubes of SOME sort. Not necessarily big exposed shiny ones like in Luis Rey's work, but perhaps buried under normal skin like with David Bonnadonna's Diplodocus head.

I think Skrepnick's painting is fine. Nothing wrong with it. Realistically, whatever conclusion Witmer reached, there doesn't seem to be much point in having the fleshy nostrils so far from the bony nares in any sort of trunk-less land animal. Such a configuration has NEVER evolved in the earth's history, so I'm not sure why Witmer's sauropods should be the sole exception. It's useless at best, maladaptive at worst.

As for your example of giraffes, it suffers from four problems. First, giraffes don't stick their noses into acacia trees. They have a very long, rubbery tongue which they use to pull branches toward their mouths. Second, African acacia trees are not all that dense. When I speak of Mesozoic conifers, I mean super dense, spiky Brachyphyllum trees. Not a few long thorns here and there, but thousands of unavoidable, uniformly spiky scales on each "tentacle". Third, giraffe nostrils are themselves heavily padded with soft cartilage inside and velvet-like fur outside, and their muzzle has hundreds of sensitive whiskers, to detect thorns that are getting too close. And fourth, giraffes are capable of closing their padded nostrils to protect the delicate membrane inside when feeding on thorny acacias. There's really no evidence that dinosaurs of any kind had the muscles necessary to do this, or ANY substantial facial muscles for that matter. Well-developed facial muscles are a strictly mammalian, not diapsid, trait.

Add to that the sweet allure of tree resin, the unforgiving roughness of bark, and the practical limits on precision and finesse for such large creatures (with large mouths to boot) and the end result is a nightmare for any nostril that strays too far forward.

And just to put tings in perspective, consider that Witmer also proposes putting theropod nostrils down near the LIPS as well as cheek-denialism for practically every ornithischian! My my, theropods inhaling blood every time they fed on a kill, and beaked dinosaurs unable to stop the chewed leaves from falling out of their mouths, no brachiosaur-like rim of outer teeth to keep it fenced in, just inner cheek teeth, without cheeks! What were these poor creatures to do????

Zach Armstrong said...

First off Nima, I never said I quoted from the paper, all I said what his "exact" hypothesis was, and that is true and was not meant to indicate that it was an exact quote, taken verbatim from the paper. Want a verbatim quote from the paper? Here you go:

"Traditionally, the fleshy nostril of dinosaurs has been placed in the
back of the bony opening, but studies of extant dinosaur relatives suggest that
it is located far forward. Narial blood supply and cavernous tissue corroborate
the rostral position in dinosaurs. A rostral nostril was, and remains, a virtually
invariant rule of construction among Amniota, which has consequences for (i)
nasal airstreaming, and hence various physiological parameters, and (ii) the
collection of behaviorally relevant circumoral odorants."

You are right that nostrils don't go beyond their bony perimeters, and that is still the case in the brachiosaurs skull diagram. If you look at the diagram, which can be seen here, you will see large narial fossae and foramina in the position where the nostrils are posited to have occured. To quote from Witmer's paper, "When scoring the extent of the bony nostril, any
narial fossae on the adjacent premaxilla and maxilla were included because they are functionally part of the narial apparatus."--Italics added. In other words, the position of the nostrils indicated in the diagram are still within the bony narial apparatus (which, it should be noted is not limited to just the fenestrae of the nares).

As for your critique of my giraffe example, it suffers from four problems. First of all, do giraffes stick their heads (nostrils included) into Acacias? Why, yes they do! While giraffes do use their tongue as you claim (see here), they don't do this all the time. Also, who is to say brachiosaurs were not well-equipped with a large tongue? Remember: absence of evidence is not evidence of absence. Second, look at that first picture again, yes, it appears Acacias can indeed be quite dense. Third, brachiosaurs had skin made out of tough scales, this was likely just as affective as the padded and fuzzy muzzles of giraffes. Fourth, as far as I know, there is no reason why brachiosaurs couldn't close their nostrils, as mammalian-style lips are not a prerequisite in order to do so (think of crocodile noses, which can shut very tight).

The EPB makes it almost certain that dinosaurs had their nostrils rostrally located, just as the EPB makes it almost certain that sauropods held their necks in raised postures.

As for nostrils being located next to the lips as you claim: no mention of lips is made in the paper (I checked), and you forget that at least theropods likely did not have lips of any sort (although sauropods may have).

Nima said...

Haha yes, that old theropod lips debate. Well I still agree to disagree :)

As for sauropods, yes they probably had lips (too). Now I'm totally against the notion that the nostrils were anywhere NEAR the lips, but there are a number of illustrations of theropods (I believe Darren Naish posted a few on TetZoo) based on Witmer's paper, one of which shows nostrils practically ON the lip line (whether you think it was literally a lip is not the issue - it's simply illustrates as being in the lip REGION, i.e. just above the gumline). I don't think the nostril goes there, but then again I'm critical of a lot of trends in paleoart, so I'm not really singling out Witmer here.

The main debate here is how big the Giraffatitan nose really was. Did the nose just include the region of the bony nares, or was it a huge fleshy sac that extended all the way to the snout tip and incorporated all those foramina on the top of the snout?

I actually venture that the nose did not extend much beyond the bony nares, though extending it further may be tempting. However, just because foramina are present (as you surely must know well), it does not mean that they supported a major fleshy structure. The foramina on the snout roof actually accompany a rather rugose surface, so it seems to me that they probably anchored some very tough skin rather than anything else.

Using Giraffatitan to prove a point, however, uncovers another flaw in Witmer's theory - how can he justify placing nostrils at the tip of the snout on diplodocids, which have no foramina on the snout roof? You can't even make the argument that the nasal structure extended to the snout. It has no traces beyond the forehead. Where is the evidence of external nasal passages?

Now for the giraffe issue:

1. That giraffe is feeding on what appears to be an acacia. But is it the infamous thorny variety? I see no thorns in the picture, and the resolution is terribly small. There are plenty of non-thorny species of acacia as well (I myself grew a couple of them in my backyard at one point), and I'm sure giraffes can see well enough to tell the difference. So in that case, they have no qualms about jamming their heads in there. Acacia leaves themselves are quite harmless, unlike the sharp scales and needles of Mesozoic conifers.

2. Giraffes don't always use their prehensile tongue, it's true, but they DO use it whenever feeding on thorny species of acacia. So this is a moot point. Whether brachiosaurs had it or not, is hard to prove either way, though the hyoid bones found with Abydosaurus may well point the way. But they seem pretty consistent with a pretty conservative-sized tongue so far, from the photos I have seen.

3. Tough scales on the snout of brachiosaurs is not even in question here. What IS in question is the hazard of conifer needles damaging the delicate lining INSIDE the nostrils. Diapsids generally can not close their nostrils the same way as giraffes, most can't close them at all. Crocodile nostrils rely on flaps to close, not a lateral slit compression as found in terrestrial mammals. A dolphin's blowhole works the same way (though blowholes of sperm whales and baleen whales follow the slit-like terrestrial model). In any case, the crocodile/dolphin pattern is an aquatic one only, here we are getting into the realm of speculation.

Nima said...

So let's speculate this: if a brachiosaur had nostrils at the snout tip, well that's a horizontal surface. And there could be all sorts of forest debris falling down onto it, a major irritation for the nostrils. Should they close all the time, or does our brachiosaur need to breathe to keep that four-chambered heart pumping? It's far more efficient to have them on the actual bony nares, on the crest - that way, they're on a vertical surface, and the chance of debris getting stuck there is minimal. Call it natural ergonomics. Indeed, the vast MAJORITY of herbivorous dinosaurs had their nostrils on a vertical surface on the face. The main exception seems to be duckbills, which were mainly grazers rather than browsers, hence they lowered their heads to graze, to the point where the snout was fading down and the nostril incline then WAS vertical (in feeding mode). Also they do not APPEAR to have preferred tall conifer forests as feeding grounds, but that's just inference from the typical duckbill habitat flora. Angiosperms in the cretaceous were actually "dwarf" trees, not tall enough to pose much of a debris hazard for large duckbills.

Nima said...

*correction*: "facing down".

Zach Armstrong said...

In an earlier comment you said there were no "scars, no grooves, no real proof." However, now you are saying that the surface around the narial fossae and foramina is "rugose". If true, then this could well be attachment structures for muscles in the nares, rather than indicating necessarily rugose skin; these then could close of the nostril openings and protect the supposed "sensitive" narial tissue. However, let us assume you are correct, that there was indeed rugose skin in the area that Witmer says the nasal openings were. Then we have "very tough skin" as you say, that could easily withstand the Mesozoic conifers which did not sport thorns like that of acacia species. Either way you go here, there is no real problem having the nostrils rostrally placed. Also notice that in the Witmer diagram, his preferred placement is at place which is not located all the way at the rim of the snout, but some distance from it (albeit, a short one), so the placement is not as "extreme" as you suggest.

I find it interesting that you now say that foramina do not require a "major fleshy strucuture" as you say, when you argued exactly the opposite side on the lips debate. I do wish you would be more consistent in your reasoning. The difference here is that the fossae/foraminae have been shown to be narial fossae and foramina, and are rather large and prominent (and diagnosable); whereas with the foramina of the supposed "lips" of theropods, if you look at bird skulls (many pictures of which can be found at www.skullsite.com), their foramina are all very similar in size, shape and placement as on theropod skulls, and we all know birds lack lips; and thus more probably indicate a rhampotheca-like structure (or toughened scales) rather than lips.

As I quoted from Witmer in my last comment above, narial fossae and narial foramina are part of the nasal structure, which means nasal tissue extended down that far. If one accepts your argument that Mesozoic conifers were as unpleasant as you say (which I doubt, after having looked at many pictures of Araucarias and other paleo-conifers; they look no more bothersome than you're average North American conifers; BTW, shorter and thinner needles are more prickly than the larger ones, of which the latter are more similar paleoconifers), that means sauropods would not have had inflatable tissue on their heads which leaves only one other reason for the placement of (relatively) large narial fossae/foraminae: that's where the nostrils were. Furthemore, I would say nasal openings are not a "major fleshy structure", or at least do not have to be, you're point is not applicable.

As for diplodocids, I quote Witmer, "the dorsal opening in Diplodocus is actually just the caudal portion of the bony nostril, and the rostral portion extends far forward as a shallow narial fossa; vascular relationships confirm a rostral nostril." This can readily be seen in high-quality photos with well-preserved skulls. Such foramina and fossae and the vascular connection can be seen here.

Zach Armstrong said...

As for the giraffe issue: (1)As far as I can tell there are no native thornless species of acacia in Africa (most are native to Australia; some are native to South America as well). One species (Acacia saligna) has been introduced, and has caused horrendous problems in the country of South Africa, but the picture above is of a Masai giraffe which live in Kenya and Tanzania which are not too close to S. Africa, so I'm not buying that argument that it was feasting on a thornless variety. (2) Your point that they don't get close up when feeding on thorny acacias and only stick their tongue out long to reach is invalid:link, as this makes it apparent that they do get close, and the tongue is barely sticking out here (and as you can see the thorns are quite large here). (3) I never said, or implied, that sauropods could close their nostrils like giraffes. That doesn't mean they couldn't close them. As far as diapsid nostrils go, members of the Serpentes have valves that close their nostrils, as well as crocodyliformes. As for lizards and birds, very few lizards and birds are folivores, and as such don't really apply here (as any meat tissue that goes in the nasals is readily cleared by a tongue or insect). As far as I am aware, most animals (except for animals that swallow prey whole and don't chew, such as snakes,etc.) don't breathe while they are eating (and I know of no herbivorous animal that breathes while eating), and thus sauropods could take breaths between bites without inhaling fragments of conifer needles. I find this argument weak, in truth, and doesn't counteract the weight of evidence from the EPB and location of the narial foramina/fossae; as it is likely that sauropods had some type of adaptation to keep their nostrils clear. Honestly, having the nares on the top in the narial fenestra, caudally located would probably be no more advantageous than having them at the snout (as far as I know, no browsing, herbivorous animal has their nostrils dorsally located), as material could still easily fall in or get stuck (as it was likely somewhat sticky as you indicate), at least having it rostrally located would make it close to the tongue which could sweep "stuck" material away.

Nima said...

This quote is golden right here:

"I find it interesting that you now say that foramina do not require a "major fleshy strucuture" as you say, when you argued exactly the opposite side on the lips debate. I do wish you would be more consistent in your reasoning."

Zach, I wish you could be consistent in YOUR reasoning LOL. On the one hand, when theropod foramina in abundance exist, in a single-line manner consistent with komodo-dragon-style lips, you try to twist them tongue-in-cheek into pinprick duck foramina and use a string of irrelevant "examples" to deny every proof of the existence of lips. (Harrumph!) Instead you say it probably anchored tough, tight crocodile-like skin, not a fleshy organ like lips.

But on the other hand, when you see some little foramina on the snout of a sauropod, you automatically assume that the fleshy nasal structures extended to the tip of the snout! (Amen!) Where is your tough, tightly stretched skin now??? Suddenly foramina MUST support a fleshy structure???

You simply take once scientist at his wors that some foramina are absolutely nasal structures. They may have contained nerves or sub-cutanous formations associated with smell or the nasal structure, but they do NOT imply that the nose was one huge sac that extended all the way to the snout tip. The rugosities don't support a pattern of low tubes either.

By the way, here is your Diplodocus skull from the front: http://www.oucom.ohiou.edu/dbms-witmer/collections/images/Diplodocus_Longus_DSC_0251.JPG

It looks like those "fossae" were nothing more than sutures in the skull that were deliberately enlarged in the cast to emphasize the shape of the skull bones.

As for there being no advantage to nostrils on the forehead... did you read that last part about vertical vs. horizontal surfaces? What about the snout being deeper in foliage than the forehead?

And to this DAY, there has never been found a living land herbivore, apart from elephants and tapirs, that has the fleshy nostrils placed more than a few inches apart from the bony nares. There obviously WAS a reason for the nares to be so high on sauropod heads, if the nostrils were really meant to be at the snout tip, then why didn't the bony nares remain there too as in prosauropods? Did sauropods all have some wacky trunk-like appendage, or some other odd nasal device unlike anything else in the animal kingdom, that we don't know anything about? If sauropods are to follow the same anatomical rules as ALL other non-trunked land-animals, their fleshy nostrils should be RIGHT ON TOP of the bony nares. Not half a meter away at the snout tip.

This debate is getting flat-out ridiculous. Sheesh, and I thought theropod lips were a thorny issue! I really want to see these fascinating long-tongued weasel nosed sauropods of yours. Why not draw a few? In the meantime, I will work on grinding out those titanosaurs.

Zach Armstrong said...

I am consistent in my reasoning: previously I said that maxillary foramina do not necessarily indicate the presence of lips, because they have nowhere been properly identified as such in any rigorous, technical assessment (yet) and because comparative anatomy suggests otherwise.

This is unrelated to the fact that there are identified as narial foramina and fossae, which indicate the presence of the nostrils, as the narial fossae and foramina are part of the narial apparatus, according to Witmer. Unless you can find a study that disputes that those foramina and fossae are not in fact narial--or that narial foramina are not associated with the nostrils, then I'd be glad to hear you out. Until then, you got bupkis. (For the record, I'm not the only one that see the "little" fossae, which are not actually all that little; Witmer sees them too, and apparently at least Matt Wedel and Darren Naish agree with Witmer's assesment (and they have also actually seen the skull in person, evidently), as does every other scientist that has referred to the paper that I am aware of).

As for the Diplodocus skull you refer to, it is on a poor angle and it is difficult to make anything out on it. It in fact appears to be a poorly executed cast, but to the left, you do see some pit-like impressions on the snout that could be narial foramina (since the lips were certainly not on the top of the snout). So it proves little, if anything but that there are few good images of Diplodocus skulls on the web.

I think your vertical v. horizontal dichotomy for nostril positions is misleading and greatly oversimplifies the matter, and as far as I am aware has no support from the peer-revieed literature.Furthermore, if the nostrils were placed on the Diplodocus skull right where the narial fenestrae are, they would be on a horizontal surface.

Again, the narial foraminae and fossae are part of the bony nares, not separate from them, so there is no "separation" as you claim, because by definition they are part of the bony nares. Thus, sauropods are still following the "rules" of all modern animals because their nostrils are in there bony nares which include the bones that house the narial fossae/foramina.

I think your worry about the nostrils being damaged by being in the foliage is not a valid point because all browsing animals today have their nostrils at the tip of their narial bones, without exception; thus, they do fine even when the vegetation can be somewhat nasty and prickly (which they often have to grapple with)--note that this includes tortoises that eat prickly cactus, etc.

Zach Armstrong said...

One last thing: komodo dragon-style lips? Have you looked at a komodo's skull recently? Where are the supposed dinosaur-like foramina? In fact, looking at other photos of other komodo skulls, I do not see the distinct foraminae that theropod dinosaurs have. Even here, where you can see the foramina, they are not at all the relative size, shape or placement in theropods, they are far larger, more space between them an not as distinct (at least on the maxilla).

Or even a close relative, Megalania, where the foramina are readily visible one can see the visible difference between that and this Tyrannnosaurus skull. Compare that to this Giant petrel skull, and it is clear that the foramina of theropods resemble those of birds far better than that of lizards, both in size and shape as well as placement.

Nima said...

Well, not quite. First, your komodo pic is overlit. The sheer whiteness of the image prevents the foramina from appearing visible.

HERE they are. Dinosaur-like foramina.

http://www.wildsidephotography.ca/Flores/23271m.jpg

And in fact the Megalania foramina do look like those of T. rex. The only real difference is that they are more widely spaced on the lower jaw. The petrel foramina are TINY, far smaller than what you find on T. rex.

Large foramina can anchor muscular lips, tiny ones are only good for anchoring tight skin or a stiff beak membrane. Your tiny bird pinpricks don't prove anything. They are a vestigial produce of evolution, in non-avian theropods they were always bigger. And your Megalania skull only proves MY point. Thanks for finding such beautiful evidence so I don't have to :) In any case, my only argument about theropod lips is that they were fairly limited, like those of lizards, so I don't see why this is even such a big issue with you. You act as if I've been restoring theropods with big floppy horse or camel lips!

But that's not even the point of this post.

The point is a new sauropod. But as for the nares, we need to understand what they ARE. The bony nares are defined by the margins of their space. The nares do not extend down the snout. Witmer just seems to take the whole face of a sauropod and say it's ALL part of the nares. So the face is basically all nose? Sounds like a bad plagiarism of the Chronicles of Narnia...

"and the nose sank back into the face (or else the face swelled out and became all nose) and there was hair all over it"

- The Horse and his boy, p. 218

This was a reference to a villain turning into a donkey. But even a donkey's face is not "all nose" considering that the nares exit the skull very close to the tip. The actual interior of the nasal cavity is roofed over by the snout bones, so the nose is essentially WITHIN the skull, not on top of the face. Only the cartilagenous tip protrudes beyond the skull bones, which have no uniformly defined margin. The problem with restoring sauropod noses the way one would restore mammals is that the typical mammal nose does not have complete bony nares with clean margins. Rather, once a skull is de-fleshed and cleaned, we see that the nasal bones of most mammals simply get thinner and dissipate feather-like into nothingness. There is NO nasal arch strut as in brachiosaurs, nor even clean margins like with diplodocids. In life, the mammal's nasal bones would have shifted into cartilage, the closer you get to the tip of the snout.

Sauropods on the other hand have clean margins to their nasal bones. All macronarians also have a distinct nasal arch strut. This is the real demarcation line of the furthest forward margin of the nose. To extend the nasal structure further forward beyond this limit is pure speculation.

Bakker actually did some of this speculation himself in The Dinosaur Heresies with regard to brachiosaurs, but he just barely glossed over it, and didn't describe the foramina in any detail. Even so, he drew the nostrils high on Brachiosaurus's fleshy nasal chamber, despite extending the chamber itself to the snout. He did mention, however, that in diplodocids, the nasal chamber is roofed over by the snout bones - i.e. that it's INTERNAL, not external. Hence the nasal apparatus did NOT extend all the way to the tip of the snout, it was inside the skull and exited at the forehead.

Nima said...
This comment has been removed by the author.
Nima said...

Furthermore, the notion of forehead nostrils is not entirely absent in diapsids. They evolved once in Phytosaurs, and they may have evolved again for different reasons.

Actually, the komodo dragon is also useful HERE. Their bony nares open up well behind the snout tip, and yet the fleshy nostrils ARE at the tip. At last, a diapsid that proves Witmer's dinosaur theory... right? WRONG! Notice how the bony nares have distinct sharp margins extending ALL THE WAY to the snout tip, as does the bony nasal arch strut. The nares are practically DUG INTO the snout bones.

http://www.azdrybones.com/images/Komodo-Dragon.jpg

In brachiosaus, the margins and the strut do NOT reach the snout tip, and there is nothing dug into the snout. The snout bones are flat on top, not carved out like the dragon's. The bottom of the nares is still up on the forehead:

http://lh6.ggpht.com/_0B9hMXxwE20/R0remDiP6eI/AAAAAAAAFhs/Fxvvy74fNqs/DSC03819.JPG

One would expect the margins of the nares and their central strut to be sharply defined as leading ALL THE WAY to the snout tip, if brachiosaurs really had their nostrils at the tip like komodo dragons. But they actually stop far short of the tip. There's no good evidence that any sort of nasal membrane lay on top of the snout, much less one with nostrils at the tip.

Zach Armstrong said...

Well, it appears we are somewhat at an impasse, as neither of us seems to be getting anywhere with each other. I will still maintain however after looking at many pictures of bird skulls, squamate skulls and theropod skulls that the foramina of theropods most closely resemble that of birds, and have major differences with those of lizards in particluar. I also maintain that while foramina do indeed supply lip muscles with nerves and blood veins, they are not a necessary and sufficient condition to infer the presence of lips.

I also maintain that the nasal foramina and fossae in Giraffatitan and other sauropods indicate nostrils at the tip of the head, as they are in nearly every other living amniote we know of! I think the problems with nostrils being hurt by branches and needles, etc., are over-hyped because all modern foraging animals have their nostrils at the tip of their bony nasals, which include bones that have narial foramina on them. Actually, the pictures of komodo dragon skulls prove my point even further, but I would need to do a labeled diagram to sufficiently explain myself. Maybe I do need a blog...

All in all, I don't have the time needed to maintain a blog; but I would send some schematics to you by email if your interested; or I could just post a few random blog posts, as I do have a blogger profile I rarely use. If you're not interested in furthering this discussion, then I say let's call it a day, and agree to disagree (again). At the very least though, I think we're making some progress in our debates, where we are not getting too heated in our phraseology, which is good. It's been a good discussion, but it is starting to get slightly unwieldy for the comments in order for me to explain sufficiently.

I'll wait to see what your decision is...

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