Re: new boook on functional morphology

[crpntr@ix.netcom.com (Kenneth Carpenter )]

You wrote: 
> Johnson and Ostrom make a very strong case (and I was very pro erect
>gait!) for a sprawling gait in ceratopsian forelimbs, and this means 
that I
>am now very confused! What are these things actually doing?


First of all, Johnson did not mount the ribs on the specimen correctly. 
Ribs do not extend perpendicular to the vertebral collumn, but are 
angled back so that the ribcage functions as a bellows for getting air 
in and out of the lungs. The way the ribs are mounted, the ribcage is 
too wide and not bellows shaped. Second, the scapula-coracoid are 
mounted too far back. As all naturally articulated dinosaur skeletons 
show, the first dorsal rib bisects the scapula about midway along its 
length. If the Torosaurus were mounted so that the ribcage was narrow 
at the front and widen posteriorly (as in all living vertebrates), and 
placing the scapula so that the first rib bissected it at the mid 
point, the coracoids would be much, much closer (almost touching) and 
the elbows would be brought in. See the Chasmosaurus mounted at the 
Academy of Natural Sciences in Philadelphia. 

As for Little Naked Jeff's idea about the sprawled forelimb providing 
stability for animals engaged in shoving contests, male deer, elk and 
many antelopes manage quite fine without a sprawl. 

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