Dinosaurs Never Held Heads High

richard_za writes "The common notion that long necked dinosaurs held there necks high to graze from treetops has been proven impossible. Roger Seymour, from Adelaide University's Environmental Biology Department and Harvey Lillywhite from the University of Florida. According to a research paper published at the Proceedings of the Royal Society in London, he explained that due to heart size and metablic rates the only way they could have functioned on land was with a horizontal neck. This flies in the face of images popularised in Hollywood movies such as Jurassic Park. However it is doubted that this new evidence will have any effect on the Mozilla Project."

Comments

mozilla will be affected most of all

[VAXGeek]

actually, mozilla will be affected most of all. they do have the slowest metabolism rate out of any open source project i've ever seen.
------------
a funny comment: 1 karma
an insightful comment: 1 karma
a good old-fashioned flame: priceless

Am I the only one...

[NecroPuppy]

...who thinks that a story about dinosaurs is somehow appropriate for election day?

Re:Hmmm...

[daskol]

this just goes along with a general unifying theory i've been hearing for a while. people used to be shorter. dinosaurs couldn't hold their heads up high. obviously, the sky used to be lower. the firmament is rising, and with grows our distance from the lord.

Never held heads high?

[sid_vicious]

Perhaps they just need a self-help videotape to boost that self-esteem?

Buck up, little T. Rex, it's all right..

Whew, bad joke. I can practically smell my karma burning.. :)

Sid

Four chambered hearts

[Epeeist]

I went to a seminar in Manchester a couple of years ago where it was argued that long-necked dinosaurs must have four chambered hearts.

Apparently if they had two chambered hearts then when they bent down to drink the hydraulic pressure would have made their heads explode.

Re:Four chambered hearts

[darylp]

When they bend down their part their front legs which squeezes the main artery to the brain to stop it blowing up.

How the HELL does something evolve like that? Like, does one giraffe look at another giraffe exploding and thinks "Hmm, maybe if I wibbled my legs apart a bit further I might be able to get away with it?" Are animals THAT self aware?

Re:Four chambered hearts

[Coward, Anonymous]

Wouldn't you expect a few screw ups like an extra half formed arm that didnt do anything. We'd all survive, we'd just be a little messed up.

In order for the person with the half arm to pass it on, they would have to have sex with someone. Given the choice of having sex with someone who has two and a half arms and another person who looks normal, what would you choose?

Reality and fiction

[iamsure]

Lets step back for a second before we bash Crichton. In Jurassic Park, he was one of the first authors of popular dinosaur fiction to display VERY controversial, and very relevant theories.

Like what?

Like the familial instincts, like the pack hunt, like the individualism of some species, etc.

Sure, the movie dumbed some of it down, but book was really very groundbraking, and the sequel was even better.

We have to understand that authors have to capture both the truth AND the common perception of things, and try their best to balance them.

oh really

[Anonymous Coward]

As somone with a biology background, if you studied the skeletal remains of a giraffe you might think the same thing. Due to the fact that I don't think there has ever been enough soft tissue find that could irrefutably say that these animals did not have valves for blood flow in their necks. I mean for goodness sakes they still are divided on if they were poikilothermic or homeothermic, if they were endotherms or exotherms...so given we know very little about their metabolism anything based on metabolism is a best guess at best :) Ok ok I did take 2 semesters of classes on dinosaurs.... Anyway just kinda found this one ridiculous.

Re:oh really

[Bilbo]

Seems that every few months we see yet another SHOCKING DISCOVERY about dinosaurs and how they lived. Everyone has his pet theory, and the more controversial, the better. The truth of the matter is, we don't have a clue!

Let's face it. We're looking at old, scattered fragments of bones. We can come up with some interesting theories, mostly by comparing ancient bone fragments to more modern species, but they are still people making long shots in the dark. Worse yet, factor in peoples' natural tendency to seek the limelight with some "ground breaking" new theory, and you see why we have these "new" theories cropping up all the time.

--

Re:oh really

[Anonymous Coward]

Hi, here is another one, who teaches zoology at the undergraduate level.

You are right. This article and its arguments are crap.

The giraffes have a blood corpuscle (like a fine branched network) which helps to relieve the pressure above (i.e. closer to the head) that network. This way the giraffes' heads don't explode from the water column when it leans formard to drink water.

Of course they were homeothermic:

1: The fine canals inside bony tissues are of a kind only found in the warm-blooded mammals and birds, but not in other amniotes like crocodiles, lizards, snakes, or turtles.

2: Birds are dinosaurs, in the same manner as bats are mammals. The are thus strong reasons to believe their most proximate ancestors also were warm-blooded. [Somewhat circular]

3: Erect posture. You just cannot walk upright for long distances, lifting your own body weight, unless you have the metabolism for it.

4: Proportion between predators and prey. In current, homeothermic ecosystems (like the African Savannah) there are about 1-5% predators in terms of body mass. In ecosystems dominated by cold-blooded predators (crocodiles or large varans) there may be up to 30% predators. In Perm, before the dinosaurs, the predators were about 10-30% of all fossils. During Triassic, Jurassic, and the Cretaceous the predators sank to 1-5% of the fossils in terms of (estimated) live body mass; the same is true for mammalian dominated fossils more recent.

Cheers!

Erect and long!

Re:oh really

[Wubby]

>1: The fine canals inside bony tissues are of a kind only found in the warm-blooded mammals and birds, but not in other amniotes like crocodiles, lizards, snakes, or turtles.

Aaaah, but a study was done that showed these canals CAN exist in cold-blooded animals because they area created based on activity, which is usually higher in warm-blooded animal, but not exclusivly. Monitor lizards but in a tred-mill developed these canals, while monitort lizards at normal activity levels did not.

Other than that I can't disagree with you.

Re:oh really

[Hard_Code]

I especially like the theory that dinosaurs were actually feathered and ran around flapping their wings to achieve higher speeds. Not that I entirely dismiss the idea. I just think it is funny to imagine all these immense and fearsome creatures flapping around like so many chickens.

Re:oh really

[Random Utinni]

While I agree with you, sometimes I feel like I need to pick a few nits... I also thought I'd provide a couple of explanations for that tiny population of non-biologists here on /. :)

1: These canals are called Haversian Canals. They're formed when bones grow. The faster the bones grow, the more canals there are. Lizards and other traditionally 'cold-blooded' animals don't grow as fast as mammals and birds, and thus have fewer canals. They do have them though... just fewer of 'em. And when snakes and crocs are kept in zoos and fed often (like once a week instead of the once a month as in the wild), they grow much faster, and have more Haversian Canals. Dinosaurs all have lots of canals, suggesting that they grew to full size very quickly (5-10 years). And we sure as hell didn't keep them in zoos... This kind of growth suggests high metabolism = warm blooded.

2: Birds are descendants of the Theropod dinos... most specifically, the line that created those raptors from Jurassic Park. Birds are warm blooded, and have 4-chambered hearts. Thus it's not unreasonable to believe that Dino's had the same. IIRC, there were also some finds that suggested that raptors had feathers (or some proto-feather type things). If you think that's wierd, think about this... An article published in a major scientific journal (I can't remember if it was Science or Nature...) reported that a paleontologist had found evidence that T-Rex had feathers as a juvenile...

3: Erect posture has nothing to do with it. It's a function of joint angles, not metabolism. Yes, it's correct that lizards actually use less energy moving with their legs jutting out than mammal quadrapeds do with their legs under them. However, upright generally means more speed. But crocs are cold-blooded, and actually can use a 'half-upright' posture, where they keep their front legs splayed, but their rear legs upright. Damn crocs always messing things up with that funky biology of theirs (They've got 3 1/2 chambers to their hearts too...). Yeah, there's a slight correlation here, but I don't think it's significant.

4: I've always been fond of this one. The argument here is that 'warm-blooded' predators require lots of food to survive and grow. In order for this to happen, there are generally lots more prey than predators. So, in the Permian (before warm-blooded critters existed), predators made up a much larger proportion of the total biomass. Dinosaurs, however, showed a much lower proportion, suggesting that they had high metabolisms.

As for the article itself, there have always been people arguing this one... it's nothing new. And yes, they're probably right that, in the absence of mitigating factors (special organs) sauropods couldn't raise their heads up. However, there are lots of options as far as mitigating factors go. Paleontologists have suggested similar organs as giraffes, secondary hearts in the neck (actually just muscle thickenings of the arterial wall that squeeze after the main heart does), and other stuff. It's all possible, and can't be ruled out.

Also, grass and flowers didn't appear until the late Cretaceous, long after the sauropods (brontosaurs, brachiosaurs, etc.) died off. The sauropods weren't swinging their necks around munching on grass. Why the hell would sauropods grow to such a large size to munch on scattered ferns?

Re:oh really

[maraist]

Ok, I'm going to go out on a limb and risk pride in saying I intuitively disagree with you. I've taken physics, but I don't deal with fluid mechanics (disclaimer). The "weight" of the water or air is totally irrelevant, as far as I can understand. It's the viscosity... resistance to movement that's different.

When in water, you can lift much heavier things.. Partly due to boyancy, and partly because the dynamics of the fluid system can act like aerodynamic lift on steroids... Namely, movement in water will have a much greater lift than movement in air. This is because the same principles of flight are amplified in a thicker system (pressure differentials are more pronounced).

Being independant of the validity of atmospheric differences back then, thicker air would not have "impeded" life forms back then in any way other than to slow them down. And in my admitedly limited knowledge in this field, it should enhance their ability for flight and even motion of larger beasts..

The first part should be obvious. The second part, however, deals with the fact that they'd have a thicker cushion of air.. Greater resistance in the air acts like a soft pillow brushing against them.. Think about trying to run through water.. yes it's difficult - requiring lots of muscle / drag (which would facilitate an aerodynamic body even for ground creatures). When you run through water, however, you're less likely to fall flat down and smack your face hard against the ground, though thick air isn't as extreme as water. This property would enhance the life of massive creatures; It would deminish the negative effects of falling, and actually help them stand up (in the presence of any sort of breeze.. just as you can easily stand on your hands under water).

In my mind (mulling this over).. If it were the case that we had denser air back then, then it could only have helped the development of avions. It is possible that animals needed size back then to live (I'd have to brain storm to qualify this more), they developed the aerodyanmics of fish, etc.. Features would help in the general lift of their heavy bodies (being able to attain some sort of lift even in the simplest of breezes).. Some actually advanced to the point of take-off, others simply had incredible jumping capabilities... As the air thinned (along with any other natural catastrophys), the creatures needed to shrink in order to survive. Those that didn't died out.. Those that were left were more than suited for air flight. The turkey must have been one of the straglers, too large in our thin our to fly, but wasn't too large to be naturally selected for extinction.

Last time we talked about Dinosaurs, I was pointed in the direction of "Saturn Theory", which is an interesting mental exercize in physics.. It's also good to turn everything you know upside down on occasion, just to keep you honest... So here's the first link I could find.

saturn theory

Re:oh really

[Twylite]

An ostrich has feathers and wings, but cannot fly. What is the evolutionary advanage in this? By studying it in its habitat we can determine reasons - but we honestly don't know what dinosaurs ate, not can we watch them eating.

Long necks can provide several advantages apart from reaching high food sources. First, long necks and tails are used by mammels today as weapons (a giraffe can kill a lion by using its head as a club).

Second, IIRC during various periods that had long-necked dinosaurs there were few trees and lots of swamp. A long neck would enable the dinosaur to reach foods on marshy ground without having to enter the marshy ground (and potentially become stuck).

Proven?

[AlphaHelix]

Nobody ever "proves" anything in any science. Particularly not when making speculative calculations about millenia old animals about whom we only have fossil information.
* mild mannered physics grad student by day *

Logical Inconsistencies Regarding Dinosaurs

[headwick]

This article addresses a few more interesting things as well.

Jurassic Park - bad example

[MupwI]

The sauropods in Jurassic Park were brachiosaurs, and they're pretty much designed to have upright necks - their forelegs are longer than the rear legs, so its head has to be higher than its heart unless there was a huge kink in its spine - ISTR the theory being that it had a big muscle in its neck that acted like a blood pressure collar which forced the blood upwards...

Re:yep. and bumble bees don't fly

[Guppy]

...at least not according to classical models of aerodynamics. See this October 97 New Scientist article, "On a wing and a vortex":

...Conventional aerodynamics--used in the design of aircraft and helicopters--rely on "steady-state" situations such as a fixed wing moving at a constant speed or a propeller rotating at a constant rate. By contrast, the motion of insect wings is a complicated 3D affair. Nevertheless, until recently researchers were not convinced that this special motion could generate any unusual sources of lift. For years, they struggled to explain insect flight using a theory rooted in steady-state situations, not understanding why their aerodynamic sums didn't add up. Ellington summarises it neatly. "Since the 1950s, we've been looking at insect flight with the wrong picture in mind."

Evolution & the long neck

[Tyrannosaurus]

Ok, so this guy has 'proven' that dinosaurs could not have held their heads high. This begs the question: why the hell did those dinosaurs have long necks in the first place?

Evolutionary theory tells us that environmental pressures lead to some trait shift in a population. I'm guessing that since they could not use their long necks to reach high foilage, then the logical answer to why the long necks is to give the carnovaurs a bigger target. Or maybe it was to counter balance their enourmous tails?

Without a living animal to ask, how do these scientists 'prove' anything with a straight face?

---

Re:Evolution & the long neck

[codemonkey_uk]

So they could have a large grazing area without moving.

Moving that huge body a step forward to take a bite of grass would have been inefficient, wherewas a huge neck would let them stand still and graze a large area.

Thad

Re:Evolution & the long neck

[SpinyNorman]

That's certainly one of the obvious possibilities, but the truth undoubtedly much more complex.

There are going to be many beneficial and detremental aspects to any genetic feature, and which of those dominate is going to change over time. Many features start out with one primary purpose/benefit which then gets subsumed over time by an alternative use as the environment or other factors change. For example, ears evolved from gills, and while ears no longer help us breath underwater, gills surely did have some benefit in picking up vibrations... Similarly a long neck may have evolved primarily under selective pressure as an efficient way to get rid of body heat, then over time the benefit of lazy grazing may have become more important, finally (in times of plenty, say) to become more important as a means sexual attraction.

Re:this WILL have an effect on Mozilla.

[slim]

AFAIK The IE team started with an already stable product (Spyglass Mosaic, itself based on NCSA Mosaic). Mozilla is a from-the-ground-up project.

But you're right that IE is a better browser: they made the (IMHO correct) decision to make a browser and a browser only: they left the mail client (for example) to the Outlook team, etc. Mozilla could learn from that.
--

Re:Giraffes

[Thag]

Giraffes also have an organ at the base of their brain which helps choke off the blood pressure, because just the pressure of the column of blood in the however-many feet of neck above their heads would do them in otherwise (think the rush of blood to your head when you hang upside down, only lots worse).

Jon

Remember to wait for peer review!

[Thag]

One paper may have "proven" this, but I'd wait a few years before I started believing it. Let's see what the others in their field say about the research, or whether other counter-theories are advanced, etc.

It's easy for one research paper to be wrong.

Of course, irresponsible persons in the mass media will immediately run the story as if it had come down from Mt. Sinai on stone tablets, but you have to remember that they're peddling journalism, not facts.

Jon Acheson

Uh, wrong

[Reality Master 101]

This is simply ridiculous. Why would a dinosaur have a long neck if it was not going to use it for any purpose? Evolution rarely encourages traits that have no function, particularly one that would create such a huge negative surivivability trait -- slows them down, more mass = more food required, more awkward to escape predators, etc.

This guy must be a Libertarian -- all focusing on the theoretical details, no focus on the objective, practical reality :). [Hey, gotta use some election day metaphors!]

--

Not "proven" or "impossible"

[Medievalist]

OK, first of all this is an old argument. No conclusive "proof" available at this time for either faction.

There are several possible anatomical features that would invalidate the math used: for example, the long-necked dinosaurs could have valvular tubing (either traditional valves like a giraffe, or structures similar to Tesla's valvular fuel piping) in their necks. There could also be muscular arrangements for peristaltic pumping and flow control - the peristaltic pumps in mammals are weak, but that doesn't prove anything about dinosaurs. I am not aware of any complete soft-tissue fossils of dinosaur necks that would prove or disprove the existence of such structures - post 'em if you got 'em.

Other arguments have been made as well - for example, if a brachiosaur can't lift his head for any length of time, he can't drop it for any great length of time - the blood would pool in his brain (rapidly, since the efficiency of his heart as a suction engine is likely much poorer than as a pressure generator). So, given that such a huge creature would require tremendous amounts of fluid intake, how did they drink without passing out? The fossils don't cluster around waterfalls as far as I know (again, post 'em if you got 'em).

Now, as computer geeks, we're all supposed to have some familiarity with LOGIC. So we should all know that it is nearly impossible to PROVE a negative - and astronomically more difficult to do so when the bulk of the evidence is obscured. Most paleontologists agree that the fossil record is necessarily incomplete due to the unusual circumstances required for fossilization and the tremendous variance of species diverisity over geological time periods.

--Charlie

Re:this WILL have an effect on Mozilla.

[f5426]

> But you're right that IE is a better browser: they made the (IMHO correct) decision to make a browser and a browser only: they left the mail client (for example) to the Outlook team, etc. Mozilla could learn from that.

Well, the mail client did not really add delay to Mozilla (because it was a separate issue). Galeon is, for instance, a mozilla-based browser that have no mail or news. OTOH, Netscape is a mozilla-based browser that will have this all-in-one approach.

Wihle I agree with you that it was a bad idea, it worth noting that the mail/news/browser/all-in-one is pretty much a requirement for AOL and for embedded markets.

Lastly, the XUL thingy will turn mozilla in an incrediblely powerfull platform (or a shitty mess, depending on how you look at it).

Anyway, I now use Mozilla more often than IE. Shift-Wheel to increase/decrease font size is quite nice...

Cheers,

--fred

Re:It's not about musculature of the neck...

[Anne Marie]

Even if its heart can't pump blood at that sustained level, there's no reason why it can't fling its head up briefly, grab a branch, haul it down, and eat it at ground level (provided there are appropriate constrictive muscles for preventing a temporary blood-pressure drop during the process). And you wouldn't need entire new hearts; simple bloodvessels can constrict in time with your single heart and provide much of the same function. (just look at your pulse, for instance.)

what if the gravity was low?

[n3m6]

as in some news article posted on slasdot before..
what if the gravity was low back then..
would they still be able to keep their heads high
or would they fail miserably
crushing their necks since they are long and
it would take very strong muscles to keep them horizontly
as everybody knows that keeping hands horizontly
extended requires more muscle toughness
than keeping their hands extended vertically
as in giraffes
just my imagination..


"The world is coming to an end. Please log orff."

Re:Simple test of this theory.

[Nickbot]

Not sure about the rest of this study, but thought this needs addressing..

Yes, it's hard for a human to hold their arm out with a heavy book.. that's because your arm wasn't made to be held in that position for many hours. Ditto the snake. Now, look at the bones of a long-necked dinosaur, you'll see they're designed exactly like the ribs of a suspension bridge. A thick band of muscle traveled along the apex, like the main suspension spans of the Golden Gate.

As for whether they held it horizontal or vertical most of the time, that's beyond me. But it's clear they did hold it horizontal at least part of the time, and it had evolved to accomodate such a configuration. (I also might add that the majority of the weight was at the base of the neck, not the head)

Just because your anatomy cannot accomodate such a position, doesn't mean theirs couldn't. After all, can you produce enough lift by flapping your arms to fly? A bird can, and that's because it has the hardware to do it with, namely a massive set of pectorals that often make up 40% of its body weight.

Re:It's not about musculature of the neck...

[JabberWokky]

there's no reason why it can't fling its head up briefly, grab a branch, haul it down, and eat it at ground level (provided there are appropriate constrictive muscles for preventing a temporary blood-pressure drop during the process).

Great! Now I have this image of a huge field of tremendously large thunder lizards all flinging their heads up to rip off a branch to eat, tearing it off, then instantly passing out, landing on their sides in a big cloud of dust.

A half hour later, they wake up, stand up shakily, and contentedly start munching on their branch.

Somehow they've lost some of their graceful appeal now.

--
Evan

"Theory" != "Proof"

[Wonko42]

Wrong wrong wrong. There is no proof of anything. There is no way to prove something like this. In fact, there is no way to prove most things in science, and I believe it was my eighth-grade science teacher who told me "In science, there are no proofs. There are good theories, and there are bad theories." This is just that -- a theory being put forth by this one paleontologist. It is nothing more than a theory, nor will it ever be.

--

"Oopsy - did I just step on your neck?"

[FFFish]

I mean, really. Imagine the accidents that would happen if they had had their heads just snaking through the grass. It'd be worse than being a python on a highway...


--

There is an ongoing debate on these issues

[Benjamin Shniper]

Many important biological issues are brought up by the gigantism of dinosaurs. Many people have theories that they were not erect, or smart, or fast, or land-based, or that they were warm or cold-blooded. But they are just theories. Nothing will be proven until we actually see one in action. Other than birds, we simply do not have any huge lizards around to find out about.

Also, millions of years ago, we believe the air was much warmer (which might have led to more land being underwater, or not). But, the air pressure may have been vastly different, the tree height different, the foliage different, the predators different. We don't know, except that probably a lot WAS IN FACT different from how the Earth now is.

So until we know the basics, like ambient air pressure, we cannot know what the dinosaurs were like. (If the air pressure was higher, and therefore the atmostphere thicker and more bouyant, then gigantism would be easier to achieve.)

Maybe not. We don't know.

-Ben

Re:this WILL have an effect on Mozilla.

[gorilla]

Wihle I agree with you that it was a bad idea, it worth noting that the mail/news/browser/all-in-one is pretty much a requirement for AOL and for embedded markets.

No it isn't. The browser should have the ability to call these programs when it's required, so that when you click on a mailto: or news: link on a webbrowser, it calls the relevent program. This gives the user the chance to replace the mail/news program with their choice, and divorces the development of these tools from the browser.

If we found and studied one

[Benjamin Shniper]

If we found and studied one then the theory could be proven. Or disproved. Yes, it would probably require a jurassic-park like experiment to figure this out, but that may be doable. (or not)

-Ben

Re:If we found and studied one

[Wonko42]

Granted, if we actually had some dinosaurs, we could prove or disprove this theory. But my point was that since all the dinosaurs died millions of years ago and time machines exist only in science fiction, we won't be getting the chance to study real dinosaurs anytime soon. :)

--

Link is to obsolete article

[tylerh]

Nice link -- but much is obsolete, or just plain wrong

We now know what finished off the dinosaurs and plesiosaurs.

we have strong evidence that the dinosaurs where thriving up until the impact.

as others have posted, the blood pressure argument only holds if the the circulatory system consisted of a heart and inelastic tubing - a fairly strong assumption. Various plausible mechanisms have been proposed to get around this problem.

Re:Hmmm...

[Troodon]

They have: The findings, the scientists claim, suggest the beast's circulatory system was more advanced than that of reptiles, and supports the hypothesis that many dinosaurs were warm-blooded animals.