Re: late night thoughts: misunderstand what?

[don ohmes <d_ohmes@yahoo.com>]

After pointing out w/ feigned consternation that Dann is now a known 
flip-flopper on tyrannosaur-stealth issues, I will intersperse comments, even 
though it doesn't work well w/ my email program. My comments are marked thusly; 
............    -- DO.

 This from a Dann Pigdon post dated 6/7/07 1724h: compare to his new comments 
further down. Hee hee.  I hope Dann isn't in any trouble for temporarily being 
on the same side.... 


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John Conway wrote:

> And where's this mega-tall, long-tailed monster supposed to be hiding?
> They'd need a lot of large and thick bushes

Dann Pigdon wrote:

I can see one possible scenario:

Hadrosaur1: "Oh no! Juvenile tyrannosaurids! What do we do?"
Hadrosaur2: "Lets hide behind that big tyrannosaur-shaped rock until they've
gone...
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don ohmes writes: 

> One kill per 3 days? Well, maybe. That's a lot of meat, though. If that is a 
> reasonable budget, that points up the advantages of a group life-style for 
> utilizing large units of food. Seems a little high, to me. 

Having enough food to last a week, and *keeping* it can be two different 
things. Even if you can fend off all those other scavengers that want their 
share, after a few days you'd have to be able to stomach meat that's 
somewhat less than fresh. If you've got the constitution of a Komodo monitor 
or a vulture then there'd be no problem though. 

......... Yep. Really would be better to be in a group from the perspectives of 
risk dilution, resource control, and resource utilization. -- DO.

> The bottom line(s)-- 
> 1). I still think the big sauropods were easy prey for tall bipeds w/ 
> powerful jaws, if and only if, those jaws could be wrapped around the neck, 
> preferably at or close to the head.

If sauropods took a long time to reach adult size (and I'm guessing they 
probably did) then a predator wouldn't have to attack fully grown adults. 
Juveniles would still make considerable meals. 

I'm sure an unusually big pride of lions could eventually take down an adult 
elephant - but the amount of energy required to do so per individual, 
multiplied by the energy requirements to feed such a large pride, coupled 
with the huge risk, probably means it's simply not worth it. Picking off the 
occasional straggling juvenile is a safer and less risky option. 

........ All true, although it doesn't really bear on my main point; adult 
sauropods were physically vulnerable to tall bipeds w/ large jaws. So I will 
say this; if elephants had their spinal cords embedded in their trunks, and 
their brains out on the end of their trunks, lions would eat all the elephants 
they could find. -- DO.

> 2). The peculiar vulnerability of the sauropod physique was the reason they 
> went so overboard on size (trying to keep those necks out of reach).

I suspect a well-aimed bite by a tyrannosaur could possibly have 
incapacitated an adult sauropod. 

....... "...suspect ... possibly..."? I know you are trained to use cautious 
language, but c'mon, Dann. What do I have to do, cite Erickson et al, on bite 
strength? <Crunch!> First the vertebrae serve as an ANVIL, enabling 
severing/crushing of all structures OUTSIDE the vertebral column. Once they 
begin to crush, the vertebrae serve as a slow form of shrapnel on everything 
INSIDE the vertebral column, 'instantly' severing communication between the 
brain and the body. Notice to everybody; this aspect of potential predation 
scenarios is really not worth discussion. Getting to the bite-point in the 
scenario, that's different... -- DO.

HOWEVER - sauropods are unlikely to have 
coorperated by standing nice and still to allow for such a well-aimed bite. 
I'm not sure how stealthy a multi-tonne tyrannosaur could have been, but I'm 
guessing most saurpods would have known about them long before the predator 
was within striking range,

............ Scenarios that culminate (or don't) w/ a sauropod neck in the jaws 
of a T rex equivalent are quite worthy of constructive debate, unlike what 
happens once that dire situation occurs. Relevant factors when evaluating 
scenarios, assuming a tree-browsing life-style; a high number of active hours 
per 24hr cycle, a high number of hours spent traversing 'fresh' territory, an 
elevated visual perspective, range/average of head elevations while browsing, 
predictable activity patterns (on both short and long time scales), and a near 
constant association w/ large vegetation. Note that all of these are conducive 
to ambush, difficult to detect by it's nature. -- DO.

 and taken appropriate counter measures (ie. 
diplodocids probably 'turned the other cheek' to put a swinging tail between 
the predator and their own 'vulnerable' heads). 

........... Now we are back in "aw c'mon!" territory. Tail swing is an iconic, 
but negligible factor in realistic predation scenarios. Remember the trees? End 
of story, unless we are entertaining the idea that when tail meets tree, tail 
wins. Which is ludicrous. -- DO.

If they lived in large groups then you'd have to contend with other 
sauropods as well. More eyes and ears makes getting into a less-risky 
killing position even harder. It would probably have been a better option to 
pick on lone juveniles or injured animals that couldn't keep up with the 
herd (tiring them out first before trying for a killing bite). 

........... Yep. Although I don't think the risk of approach was high, 
especially when the prey was doing the approaching. -- Don Ohmes.

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Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.soffiles.com
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