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RE: Bipedal apatosaurs and stegosaurs?

GSPaul writes;

>The assertions by one or more contributers to this board that rearing by
>sauropods would be energy inefficient is entirely false. The energy cost of a
>sauropod rearing would be trivial compared to the large number of calories to
>be gained that would be otherwise out of reach.

This would depend on the nature of the dominant conifer.  I proposed
earlier that the "typical" conifer wouldn't be much taller than a
Brachiosaurus.  If this is an upper level, then an animal like Barosaurus
wouldn't need to rear to get at the best needles.

There is another possibility in the rearing debate.  The differing body
plans of diplodicids and camarasaurids could represent ecological
stratification.  An animal like Brachiosaurus could be seen as a canopy
feeder (and would probably clean up the treetops quite easily).  If a
diplodicid were to try to feed at the Brachiosaurus level, it would either
find very little to eat, or would find itself in direct competition with
the Brachios.  To avoid competition, the diplodicids instead focus on being
medium level feeders, eating at the level that is just below where the
Brachios can effectively reach and the ground.

>Consider that elephants will
>walk 20 miles in a day to reach a food source.  Here we are talking about an
>animal lifting its body a few feet to reach many pounds of food.

Ummm, a diplodicid would have to lift it's body quite a deal more than a
few feet, especially if the animal wants to have any stability.  Beyond
that, migration would be in a different class from rearing.  Animals
migrate because they must to avoid starvation.  As I have proposed,
diplodicids simply didn't have to rear to get adequate food supplies, the
neck would do just fine all by itself.

Rob Meyerson
Orphan Vertebrate Paleontologist
"Can't I have a little bit of peril?"