[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Sauropod neck positions: "High" is a relative term.



Phillip Bigelow wrote:

> Apatasaurus:  Couldn't get it's head up as high as previously
> thought.
> The neutral position for ALL the cervicals puts the
> neck pointing toward the ground!  Because the occipital
> condyle is sort of set at a 90 degree angle to the head
> length, the head is tucked down relative to the neck
> axis in the neutral position.
> The neck/head was quite flexible in the ventral direction,
> and the animal also had extremely good flexion side to side
> (Parish showed an illustration of 180 degrees flexion side
> to side).
> The maximum vertical reach of the head above the ground
> was only 5 meters (15 or so feet).
>
> Diplodocus: Neutral position of entire complex: head also
> points down almost to ground similar to Apatsaurus.
> Very little side to side motion (compare to Apatasaurus above).
> But even more ventral flexion that Apatasaurus.
> Not so much flexion in the dorsal direction.
>
> Barosaurus (work in progress): Quite stiff-necked animal.
> BOTH vertical and lateral movements are limited.
>
> Brachiosaurus: head was indeed held higher than other
> sauropod families, but not as high as previously thought.
> Neck was, compared to the above animals, more stiff,
> and probably more straightly-held.
>

I've heard this idea that sauropods were actually low browsers/grazers
before.  Didn't make sense to me then, and I'm afraid it still doesn't
make much sense to me now.  There are a few questions that are just
crying out for answers.  For example:

* If all sauropods were low feeders, then why were there so _many_ of
them, with such a tremendous variety of sizes, head designs, and neck
lengths?  That sort of variety says to me that they were occupying
different microniches, and the most obvious microniche for herbivores is
_food_.  Each sauropod had its own neck and head design to reach its own
preferred food.  That makes sense if they were browsing at different
levels of the upper canopy, but not if they were all picking and
choosing from somewhere down near the ground..

* Few sauropod skulls are known, but those few that are known all seem
to be built in a way that has a wide acute or right angle between neck
and head.  That also makes little sense for a low-level browser, and
lots of sense for a high-level one.

* If sauropods were low feeders, then why did the brachiosaurs develop
such long forelimbs?  Moving the head and neck away from the primary
food source seems a little counterproductive.

One other point: as a programmer currently wrestling with a _really_
screwed up database, I can tell you for a fact that the fact it comes
out of a computer doesn't mean it's necessarily right! <g>  Computer
analyses and animations are great and wonderful to watch, but they
aren't always correct.

-- JSW