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Re: Lack of Running Giant Theropod Tracks
On 11/28/2010 6:44 PM, Sim Koning wrote:
Here I was focusing on the high probability that Triceratops was the one of the
largest, most powerful and dangerous animals in its ecosystem *and* it may have
been quite fast.
OK, trikes were problematic gut-pokers. We agree there.
I'm guessing that you were intentionally exaggerating with the boy scout
comment, since some large sauropods would have been able swallow animals the
size of a human child whole,
Not really. A gutsy young lad from (e.g.) Wyoming could do in a
brachiosaurus in if he could get a bull rope on him in the right spot --
there were portions of the neck that were inaccessible to the sauropod.
It would seem that finding a convenient tree to scrape the kid off with
might work. But not if that trusty Randall knife was really sharp. No time.
How far would a severed sauropod artery spurt blood? How many liters per
and may have done so occasionally in order to increase the amount of calcium
and essential amino acids in their diet.
Here is an example of said behavior:
And here is a perfect chance to mention a pet "could-have-done" I never
saw mentioned anywhere else -- any sauropod that went into water
regularly was undoubtedly presented with temptingly immobilized
silt-stunned fish. A line of sauropods could have harvested large areas
by silting up the water column and reducing O2 levels... *could have*.
Again, I assume you mean sauropods. I am flabbergasted every time this
comes up on list, and I mean nothing personal in this. Everybody seems
to agree w/ you, but can offer nothing to defend this intuition become
No, not specifically, since ceratopsids, giant ornithopods and ankylosaurs are
not sauropods. You are either intentionally or unintentionally forming a straw
man version of my argument.
I did that, but it was unintentional.
Given that T. rex was the only mega-theropod (afaik) that might *not*
have had "the sauropod option", and also lived late in the dinosaur-ian
era, I did not see any reason to exclude sauropods -- especially when
how they both evolved to what they were is at the root of all these
debates. So I jumped to a conclusion...
Try a thought experiment -- drop down on all fours and become a
sauropod. Your neck is now as long as your torso, and as big around as
your finger, or maybe something a little more sensitive. How big is your
head? Really, really, small...
I would rather look at the actual animals and compare them with living analogs.
There are none, unless you count the relatively tiny giraffes. Even
there, where is the tall biped w/ neck-encompassing jaws? We have to
stick with the morphological realities the geo-record gives us.
To start with, you are greatly exaggerating how small these animals heads were:
they may seem rather small relative to their body size, but in absolute terms
they were quite large. As an example, the skull of the Brachiosaur in Chicago
is large enough for me to fit my head and shoulders into and I'm nearly 6 feet
No. Relative to mega-theropod jaws, their heads and necks were tiny.
On ground where it's mobility is not impaired, any small and aggressive
dog could kill you easily with one bite should it be able to teach your
neck, even at the base.
I do not weigh 35 tons or more, and I do not have neck ribs protecting my
throat and my carotid arteries. Also does your thought experiment allow me to
rear up on my knees and smash the small dog with my fists? When you consider
that giraffes use their head and necks as *weapons* the necks of sauropods may
have been nearly as dangerous as their tails.
You guys who believe in the Zeus-like enraged sauropod should read --
"Proc. R. Soc. B -- doi:10.1098/rspb.2010.0898" aka "Scaling of
sensorimotor control in terrestrial mammals -- Heather L. More1, John R.
Hutchinson2, David F. Collins3, Douglas J. Weber4, Steven K. H. Aung5
and J. Maxwell Donelan1".
My take -- unless dino nerves were really special, the really big guys
were, in fact, really really slow.
"Dogs" are not slow, _when on good footing_.
To abandon the dog analogy -- a biped in deep mud would be in deep
doodoo. The binary implications of substrate type cannot be ignored or
overstated when assessing the respective capabilities of sauropods and
theropods, or cataloging possible ecological scenarios. Anyplace a biped
is very likely to fall, advantage sauropod. Anyplace the theropod can
dodge and circle at will, advantage 100% theropod.
Predators do not need to eat very often, and extremely large herbivores
do. How long do you think you can "rear up and thrash your tail"? Who
gets tired first? Are there trees or rocks? Well, then forget about
doing any tail-thrashing...
You are begging the question by assuming that sauropods would have been
extremely slow and almost helpless.
I do assume they were relatively slow -- as in the slowest ever. I also
assume they could and did get tired and de-hydrated. Anyother
assumptions are special pleading when assessing the respective
capabilities -- as is the old "they were just so big the theropods would
be terrified" behavioral argument.
You are also assuming that the risk of being trampled on by 50 ton animal and
being struck by a swinging neck/tail would be low enough to make the attack
worthwhile for a large theropod. There is no reason to presuppose either of
these things since giraffes and elephants are both more than capable of killing
lions and other large predators.
There are no extant analogues. Lions are not tall enough to reach
giraffe necks, and elephants do not have spinal cords, major arteries,
and brains in their trunks. Taking the theropod's perspective, I repeat
-- on certain footing, the risk was minimal. In water/mud deeper than
the theropod could stand, but shallow enough to give the sauropod
footing, the risk was suicidal.
Old story -- S Douglas (very short, but an excellent marksman): "I
challenge you to a duel." Abe Lincoln (tall, an awful marksman): "OK.
Pole axes in 6 feet of water." Douglas: "@#$! $%! %!!!!"
Imagine how easy an elephant would to kill if all you had to do was bite
the end of it's trunk. Think about it.
That's a fallacious argument because it's based on a false analogy: saurpods
necks and elephant trunks are only similar in that they are elongated...that's
it; some macronarians had heads large enough for them to actually bite back!
No, it isn't. Sauropod necks were mostly air, blood pressure extremely
high, and very long. A 3 or 4 ton load on a 10 meter lever, and the most
benign attachment points are mere centimeters away from nerve, muscle,
vessel, maybe brain -- one crunch, game over.
Tactically speaking -- a sauropod in a parking lot would be easy meat to
a persistent giant theropod.
If sauropods were as helpless as you seem to think they never would have evolved in the first
place. Predators do not have some sort of "conservation" instinct: predators such as
wolves will slaughter entire herds of sheep if they are helpless and can not get away. I have a
feeling the same would have happened to sauropods if they were such "easy meat".
I disagree. Their vulnerability is why they were what they were -- they
had to get the base of those necks as high as they could. Even so,
relative to the tactical implications of the respective morphologies,
they were helpless on flat ground, unless they could get to refuge. See
The other half of the coin must not be ignored -- a sauropod in a swamp
or other place of uncertain footing, with deep footprints and knocked
down trees inter-laced everywhere, was nearly as safe from the bipedal
theropods as we are today :D...
That or it could simply be because sauropods went extinct for whatever reason
in North America and a species of titanosaurid migrated from another continent
via a land bridge or an island chain. The formations that they are found in
also span nearly 10 million years. Is there any evidence of Alamosaurus
increasing in size along with the tyrannosaurids?
Could be. Actually, didn't the allosaurids and the sauropods disappear
for N America at approximately the same time?
I've read two of Hutchinson's papers so far and I found them very interesting, but I think the
media (and most people in general) seem to think that studies or experiments equal
"proof". The reality is there is no such thing as "proof" in science (outside
of mathematics), only evidence. I imagine John Hutchinson would be the first to tell you that there
are a *lot* of unknowns when forming computer models of an animal that has been dead for 65 million
years. That being said, 25 mph isn't exactly walking, it's actually pretty fast. I would be
interested to see how models would turn out if they included highly elastic tendons somewhat like
those seen in macropods (kangaroos), which seem to hold up well under increased weight. I'm sure
that was factored in to some degree since most or all tendons and muscles can work like springs.
I'm also stumped as to how a 100 ton sauropod could support its weight if a tyrannosaur had just
enough strength in its legs to walk quickly (10-15
mph) and not run.
Heh. I doubt JR Hutchinson would ever say "We know it all, I am going to
As to the rest -- there is a big difference between bipeds and
quadrupeds in terms of what an engineer can do design-wise.
And 25 mpg is fast. Too fast, imo.
People make a big deal of risk-avoidance by predators -- "Hmmm -- should
I run 25 mpg on rough ground after something with horns everytime I get
hungry, or should I crunch one skinny neck and feed the whole family for
a week. Choices, choices..."
Seems simple to me, when viewed from a combined ecological and "opposing
The biggest herbivore ever can be killed with one bite, and the null is
that the species we know were ideally suited to bite them in that deadly
spot were too scared to do it? Sorry, I do not buy it.
PERHAPS the very largest adults of the very largest species would have
been marginally safe out in the 'parking lot' - but I doubt even that,
unless it is true that the mega-theropods were big chickens.
Golden eagle-type aggressiveness was more likely, in my view.