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sauropod feeding dogma*



Robert.J.Meyerson and Stan Friesen have challenged about the modern 
dogma that all sauropods fed from trees. I'll respond to both:

>Your going to have to include _Brachiosaurus_ (one of the largest
>sauropods) in this. 

My two examples, camarasaurid and diplodocids, were two extremes of 
sauropod muzzle shape. Because Brachiosaurus has a camarasaurid-like 
skull, listing it added little new information.

>then it seems reasonable that there had to have been a few
>conifers that were tall enough to fill the order (any idea on the
>geologic range of the sequoias?).

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

These two points are similar to the argument that  "created" giant 
lakes in the Morrison Formation so that the sauropods could stand with 
only the top of their heads poking out, i.e., creating evidence to 
support a preconception. In addition, there is a false assumption that 
trees of the Jurassic were so closely related to certain trees today 
that they did not evolve much. This is a false preconception that 
paleobotanists, such as Kirk Johnson here are Denver, are now fighting. 
As I wrote, the fossil evidence in the Morrison Formaion does not 
support the exsistence of many giant trees.

>Broad muzzles are indicitive of *non-selective* *bulk* feeders.... A
>narrow muzzle indicates a selective feeder, some of which are also
>grazers today and low browsers...Thus a broad muzzle does not nec
>essarily indicate a low feeder, only one that wolfs down its food
>without much selection.

Isn't that what I said? You can also check Carpenter, 1982, Canad. J. 
Earth Sci. 19, p. 695.

>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.

More false asumptions: 1, that all ecological niches of the past are 
present today (e.g., we don't have 30 ton terrestrial herbivores) or 
2), that all morphological adaptions we see today can correctly set the 
limits behavioral interpretations of the past. But if "long necks 
apparently do NOT evolve for low reach, only for high reach," then that 
means that tanystrophids (a semiaquatic reptile of the Triassic) must 
have fed on flying fish or flying insects. But as veni, vidi, concreti 
pointed out:

>err, ostriches etc....um geese are grazers err swans (ok you could 
>look at these as upside down high level feeders...)

Thanks. 
The point is that the giraffe model have been miss used, over used and 
abused.

>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,

Do I detect someone having second thoughts? ;)
I never said all sauropods feed on the ground. Reread my original 
message. I clearly stated that I dispute having all sauropods feeding 
in trees and pointed out that diplodocids were probably low browse, 
i.e., non-selective, feeders. Both Camarasaurids (and brachiosaurids) 
are tall in the front AND have a narrow muzzle, suggestive of selective 
tree feeding. Diplodocids are NOT tall in the front nor do the 
vertebrae indicate  the neck was carried erect (sorry, Greg).

Kenneth Carpenter
Dept. of Earth Sciences
Denver Museum of Natural History
2001 Colorado Blvd.
Denver, CO 80205
crpntr@ix.netcom.com