April 13, 2011 • 5:19 am

If you think elephants are big, take a look at this graphic from yesterday’s New York Times comparing the size of the sauropod dinosaur Brachiosaurus with an elephant and a human (click to enlarge):

Sauropods were an infraorder of dinosaurs that included everybody’s second-favorite dinosaur,  Brontosaurus (unfortunately renamed Apatosaurus). The Times article on sauropods, by John Noble Wilford, is centered on a new book, Biology of the Sauropod Dinosaurs, on an exhibit on large dinos opening this Saturday at New York’s American Museum of Natural History, and on recent published research.  The interesting stuff involves their size and their diet.  First, look at another figure (from Wikipedia) showing how huge they were.  Wikipedia says this about the big guy in red below:

The holotype (and now lost) vertebra of Amphicoelias fragillimus may have come from an animal 58 metres (190 ft) long; its vertebral column would have been substantially longer than that of the blue whale. The longest terrestrial animal alive today, the reticulated python, only reaches lengths of 8.7 metres (29 ft).

Note that a Boeing 747 is only about 35 feet longer than this sauropod!

The main issues are two: what was the evolutionary advantage of getting so large, and how did they sustain such a big body?  The article doesn’t really answer the first question (avoidance of predation is one possibility), but there are hypotheses about the second.  These dinosaurs didn’t have molars, and basically couldn’t chew—they simply took big bites of the vegetation and swallowed it whole.  Since their food intake was enormous (the 60-foot Mamenchisaurus, not a particularly large sauropod, ate about 1,150 pounds of vegetation per day), they might have evolved those long necks to cover more grazing area without having to expend energy moving their bodies.  And since they didn’t chew, their heads could remain small.

The figure at the top shows how much grazing area a sauropod could reach if it had a neck of a given size.  Because the neck is in fact a radius of consumption, the area accessible to the beast goes up roughly as the square of the neck length.  Even given this efficiency, scientists estimate that it took about two weeks to digest one day’s food intake.

They also grew fast: one recent paper estimated that baby sauropods doubled their weight every five days.  Their hearts probably beat at a rate of about ten per minute, compared to 28 for an elephant.   One big mystery is how they got enough oxygen to fuel their metabolism: some scientists think that they had a respiratory system like birds. (Birds supplement their lungs with several air sacs producing gas exchange with the blood.)  But one of my Chicago colleagues is dubious:

Paul Sereno, a dinosaur fossil hunter at the University of Chicago, said the new research “is very valuable,” but he doubted there was enough hard evidence to support the bird-lung hypothesis. Still, he said, the sauropod “is an incredible animal, one of the best land animals that’s been invented.”

39 thoughts on “Sauropods!

  1. — Still, he said, the sauropod “is an incredible animal, one of the best land animals that’s been invented —

    Oh cool! Invented! I’m gonna steal that. To pre-empt (or avoid) the inevitable evolved-created discussions.

      1. but this is why every scientists should be careful of what he says – why couldn’t he use “evolved” insted of “invented” ?

        1. Eggs.

          No kidding, that’s their answer.

          The Ark had dinosaur eggs on board.

          Never mind that it’s a clear violation of the instruction…two of every kind (treif); one male and one female. Apparently Noah’s wife was a great egg sexer.

          1. Wow, I knew those bright folks would have it figured out. I guess that minor change will save on Ken Ham’s costs at his splendid new theme park too.

            Can the current non-existance of these magnificent creatures is due to Noah having a quick omelet for dinner one night?

  2. “one of the best land animals that’s been invented.”
    So, it was “invented”, ha! Expect that to be quote-mined in the near future!
    On a more serious note, I’ve read somethere that the oxygen content of the triassic was higher than present and this allowed for such large body size. Is this a consensus opinion or just one of competing theories?

    1. I know that’s the reason for the large bugs. Considering how much extra oxygen would have to be in the atmosphere for a dragonfly to reach the size they did in the Jurassic, I could imagine it made things easier on Sauropods.

      (Also; /pedant Sauropods were primarily Jurassic and Cretaceous in distribution. Prosauropods were generally Triassic. /pedant.)

      1. Ooops, I meant mesozoic rather than triassic – I keep getting my time periods mixed up.
        I’m a molecular biologist, not a paleontologist!

  3. Were these large auropods viviparous? It seems very hard to lay an egg from such a height without damaging it…?

    1. You can’t make dinosaurs without breaking eggs!?

      Seems there is a simpler solution. How about laying down and presenting the egg to the ground, as I presume turtles, snakes, birds et cetera (still) do today?

      1. Surely not – they were SO big…?
        The effort to get up, the strain on those massive bones…?
        I meant Sauropods – it was not their feet that looked like ears!

    2. I don’t know what the fossil record tells us (if anything so far) about how they layed their eggs but I think this is an easy problem to solve… Any one of the following, or a combination, could do the trick:

      (1) squat and squat deeply
      (2) lay eggs on a nest-mound, probably built by the parents — high enough for soft landing, small enough to straddle over
      (3) a fleshy tube-like ovipositor that reach almost to the ground

      1. I thought ovipositor but there is not going to be any fossil evidence; nest mound might work; but squatting at such a huge size? large animals on the ground find it very hard to stand up, these are massive animals. If they fell they would surely die…? I would bet on live birth. Icthyosaurs did it…

        1. I’m no expert on this stuff, but I did poke around online a bit, and there is fossil evidence of sauropod eggs, so live birth seems out. Also, the nests were dug into the ground, not built into mounds. (Relevant article @ JSTOR:

  4. Would quick growth and large adult size protect from predators thereby providing a selective advantage?

    I retain a child like awe if dinosaurs. Went to AMNH in NYC last year and was blown away. Need to take another trip there sometime soon.

  5. Because the neck is in fact a radius of consumption, the area accessible to the beast goes up roughly as the square of the neck length.

    Heh. Trust a newspaper to illustrate a fact in the least illustrative way possible. Their graph makes it out as a mystery why you would want to lengthen the neck after the first couple of meters.

    Mass going up as the cube of length would slightly offset the gain, but presumably if you don’t need much to run (horses et cetera) or wander (savanna animals) you would hit on longer necks off the bat.

    Birds supplement their lungs with several air sacs producing gas exchange with the blood.

    I think this was covered well a couple of months back, but they also have flow lungs which can optimize gas exchange all the way through the flow duration. Our bellows cul-de-sac lungs is the worst possible solution (but tell creationists that) for larger animals.

    Though if I remember Genomicron right, they have missed optimization potential too. Didn’t birds have mostly nucleated red blood cells, so they can’t shrink them for area-volume ratio and so the blood vessels as much as we do?

    I guess the “optimal”, whatever that means, animal hasn’t yet been invented by the great but obviously blind tinkerer evolution.

    After a 2nd hearth/aorta system and a brain case pressure relief valve, bird lungs would place high on my list for genetic enhancement of humans. The first takes care of common ailments/increase life expectancy. But the later makes you fly! (Well, not literary.)

    Too bad all of them likely are massive multiple genetic traits. Guess I have to settle with new eye colors and funny skin, hair and ear patterns for starters as in bred animals. Why does cosmetics have all the fun? … Spock/elf ears, ooh shiny!

    1. The idea of tinkering with human evolution by adding new genes is not quite as science fiction as one might imagine. In theory the idea of adding a new gene to a germ cell should be technically much less damaging (due to the lack of major epigenetic changes) than wholesale ‘cloning’ and we are now getting the results of animal models that show the results of adding parts of the telomerase pathway (massively increased lifespan!) and the results of adding additional copies of tumor suppressors like p53 or p16 (reduced levels of cancers).

      1. Thanks for mentioning this! Do you have any reference to any of those results, perchance?

        So, agreed. But those are even less impressive on the outside and for your own notice, you need to get tattooed “Ah haz evolvd” after. [/pouts] (Though I assume two hearths would be noticed, come to think of it.)

        I think I read briefly somewhere they now (try to) add genes as plasmids instead of by somewhat haphazard virus insertion into the nucleus.

        [What do you now, Wp: “Zinc finger nucleases (ZFNs) offer a way to cause a site-specific double strand break to the DNA genome and cause homologous recombination. This makes targeted gene correction a possibility in human cells. Plasmids encoding ZFN could be used to deliver a therapeutic gene to a pre-selected chromosomal site with a frequency higher than that of random integration.”]

        So away with random insertion and epigenetic changes, and in with putative “non-natural tinkering”? I can live with that; in fact I guess my grandchildren have to.

  6. HAHAHA the evilutionists lose again! By depicting humans and dinosaurs together, the NYT has just endorsed creationism! The mainstream media is slowly but surely recognizing the Truth.

    Oh and a little advice to the godless miscreants here: cats and saxophones are a waste of time.

  7. Let’s clarify the lung thing.

    Birds supplement their lungs with several air sacs producing gas exchange with the blood.

    That’s misleading at best. Yes, birds have an impressive set of extrapulmonary airsacs (these extend into the interior of the large bones). However, negligible actual gas exchange takes place in th air sacs–they are not lung supplements.
    What they do is set up the complex anatomical system that pumps fresh, oxygen-rich air in a one-way flow through the tubular lungs on both inhalation and exhalation. Together with a “cross-curent” arrangement of blod capillaries, this makes the bird l;ung a very efficient oxygen-extraction machine.

    Always remember, though, that bats fly just fine with mammal lungs.

    Some of the most intereswting recent research in comparative physiology has shown that crocodilians share many of these features with brids: tubular parabronchi (instead of blind-sac alveoli), cross-current perfusion, and even one-way airflow, despite lacking airsacs. By the principle of phylogenetic bracketing, we can confidently assign these features not just to sauropods, but to all dinosaurs (and pterosaurs). And sauropods in particular left highly pneumatic bone tissue that is a sure sign of bird-like supplementary air sacs.

    So there really is little doubt that sauropods had a bird-like respiratory system. The weak link in the reasoning chain, however, is the claim that bird-lungs–i.e. high oxygen extraction efficiency–somehow explain their huge size. It’s not at all clear.

    1. Depending on the extent of the theoretical air sacs it helps to explain that a very large size does not necessarily mean a very large mass. The puzzle of how such a giant could even stand starts to fade.
      Hmm…maybe the dinos in the museum gift shop weren’t the first foam ones.

  8. Lovely. A full-colour picture of a Brachiosaurus is one of my oldest childhood memories.

    Until the age of about 5 I was hopelessly behind in reading, largely because everything I’d been given to read was so deadly dull. Then my parents gave me two books full of not just words but also pictures of dinosaurs, and I’ve not looked back since.

    That’s right, Dinosaurs taught me to read!

  9. The grazing area reachable while standing still is not terribly important to grazing efficiency, nor is the “number of grazing areas per acre”. Once an area is consumed, the dino has to move, and moving just a couple steps results in an area that mostly overlaps the previous area, so the dino has to move further. In fact the distance to move to a fresh area would be linearly proportional to the neck length which knocks one factor of neck-length out of the grazing efficiency (area covered divided by movement required).

    Having 2x longer neck gives 4x stationary grazing area and 1/4th the “number of areas to cover an acre”. Does this imply 4x efficiency? No. The dino with the shorter neck will only need 2x the movement to reach its 4x as many “areas”, because it only needs to go half was far to reach the next area.

    What *will* impact total grazing area over a period of time is the width of the swath cut by the sauropod as it moves across the landscape. After moving, say, a kilometer, the extra, say, 20 meters *forward* it gains from neck length is insignificant (just 2%, much smaller percentage for longer distances walked), but the fact that it cuts a swath 40 meters wide is very significant. The total area covered would be 1020 meters times 40 meters, and this area grows linearly with neck length, not as the square.

    A way to visualize this is a tractor plowing a field. If the plow is is 2x as wide then it needs to go back & forth across the field half as many times, but each trek across the field is still the same length as with a narrower plow, so you cover the same area for half the distance moved not 1/4th the distance moved.

    1. Interesting, S.K.Graham. This makes me think of the way that whitetail deer (browsers) have been shown to modify their food intake. Rather than reaching farther, they keep their necks within a fairly narrow range and just walk faster to take in more food.

      This strategy is better for the plants upon which herbivores feed, too. Plants that are damaged less are more likely to survive predation to produce more food. Envisioning such a large herbivore that eats everything within neck’s length before moving on requires an enormous habitat range and/or small population densities.

  10. I have a great book from when I was a kid called “Giants of the Land, Air, Sea, Past and Present”. It was just a series of pictures like the first one, large animals from throughout history alongside a typical human male and female for comparison. It also had a brief blurb about each creature and vital stats like size and weight. It included standard stuff like dinosaurs, as well as extinct mammalian megafauna and ancient, pre-dinosaur giants like sea scorpions and an amphibian version of a gavail, and of course modern species like elephants, ostriches, whales, lion’s mane jellyfish, and giant squid.

    Overall the book is excellent, with extremly beatiful and detailed illustrations and an eclectic combination of well-known and more obscure species.

    Unfortunately I got mine used from the library (I checked it out so often my mother finally just got them to sell it to us), and I read it a lot so it is in pretty rought shape.

  11. What do you mean “unfortunately renamed Apatosaurus”? The Apatosaurus name was introduced two years earlier than Brontosaurus, and the latter was only applied to a skeleton that its discoverer, O.C. Marsh, believed was a completely different genus and species of animal, an idea of which has been rejected since 1903. So, based on proper nomenclature ‘Apatosaurus’ takes precedence over ‘Brontosaurus’.

    1. You’re obviously correct about the chronology (and thus primacy); I think Jerry just means that Brontosaurus is a cooler name than Apatosaurus. And it is.

      1. I don’t agree that Brontosaurus is cooler. I think Apatosaurus is the cooler name; it sounds articulate and cultured, and compared to Brontosaurus it has a faster sound to it. Whereas Brontosaurus sounds slow and lumbering, and basically fat, and for that matter uncultured.

  12. Who is the little blue guy in the second picture? Did he invent the dinosaurs? He’s in so many of these dino pictures, but not always dressed in blue. Is he a time traveller? He seems very friendly. Does his wife know where he is?

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