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Re: dogma of tree feeding sauropods



From: crpntr@ix.netcom.com (Kenneth Carpenter )
 > I do not accept the modern dogma that all sauropods were tree feeders. 
 > ...   2) The fossil evidence 
 > for trees so tall that sauropods needed to rear up is very piss poor. 
 > There are some large logs in the Morrison, but few indicate 100+ ft 
 > tall trees.

1) The living relatives of some of the Mesozoic trees are in that
   size range: consider Pseudotsuga, Sequoia, some Auraucaria spp,
   among others.

2) A tree need not be 100+ ft tall ofr such tree-feeding adaptations
   to be significant.  Giraffes feed mostly in trees 30 to 50 ft tall.
   Brachiosaurus is optimized for feeding at about 40 ft., and even
   in a tripodal stance, Diplodocus would not be able to reach much
   higher than 50 ft or so.  Thus the size range to be considered
   is really 30 to 70 ft, not 100+.

 >  Considering that the dominant vegetation was ferns (over 
 > 200 species based on pollen, Litwin, pers. com.), I see no need to 
 > invoke sauropods rearing up to feed on 100+ ft trees. 3) the broad, 
 > squared muzzle of diplodocids is more similar to that seen in the hippo 
 > and white rhino, both of wich are low ground cover croppers.

Broad muzzles are indicitive of *non-selective* *bulk* feeders. While
many such today are grazers, they need not be. A narrow muzzle indicates
a selective feeder, some of which are also grazers today and low
browsers (check out the muzzle on a pronghorn).

Thus a broad muzzle does not necessarily indicate a low feeder, only
one that wolfs down its food without much selection.

 > 4) The 
 > long neck of diplodocids would allow them to crop a larger area of 
 > ferns, etc. in order to fuel their large mass.

Name one other long-necked group that feeds below shoulder level!!

The simple fact is that long necks apparently do NOT evolve for
low reach, only for high reach.

It is certainly possible that the long neck originally evolved for
high feeding (in the prosauropods), and then was co-opted for a
long, low reach later.  But it seems unlikely to me that this
happened in *all* sauropod lineages. (In fact I have concluded
that Apatosaurs may well have fed as you suggest, as it differs
from other diplodocids in ways that suggest it was less able to
assume a tripodal stance).

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.