re:tucking

["Cunningham, Betty" <bcunning@nssi.com>]

     >...as opposed to Peter Galton's now-old picture of a hadrosaur
     >running bipedally with the arms all the way back, like the basilisk.  
     >ICK! Are they tucking simply to get the arms out of the way?  Having 
     >longer arms that are used in quadrupedal locomotion would necessitate 
     >getting them out of the way.
     
     After thinking about the stuff I sent yesterday, and seeing this, I 
     want to change my initial statement slightly.  Moving limbs out of the 
     way while tucking is VERY important, and a secondary consideration for 
     the appendages NOT being used for locomotion..  (I realized last night 
     THAT is why both ostrich and emu raise their wings during extended 
     stride running, not merely for cooling, but to give more clearance to 
     the upper thigh during the stride).
     
     This is something the large-limbed therapods and dromosauridae would 
     just about have to do during an extended stride so thir hindclaws 
     don't tangle with their forelimbs.   Any of the 
     Veloceraptor/Deinonychus group would HAVE to run with their arms up 
     and forewards as the damn foot-claw would need lots and lots of 
     clearance.
     
     Also, while kangaroo ARE bipedal (sort of) AND have tails, I long ago 
     discounted kangaroo as a viable comparison for dinosaur because of the 
     wierd hip/femur structure they (kangaroo) have.  I had a comparitive 
     anatomy instructor in school that pointed out that kangaroo simply 
     can't take alternate strides with their back legs.  Their hips won't 
     let them.  They do that wierd foreleg/backleg reach-and-hop, or the 
     big bounce, but they neither walk nor run.  I don't even think they 
     could scratch behind the ear with one foot as most animals do.  Their 
     hips simply won't let them.  I spent several weeks at the SF Zoo 
     during this class, drawing and observing kangaroo and wallabies, and 
     never saw one take any kind of alternate stride.   Wierd, isn't it?
     
     Betty Cunningham(Flyinggoat@aol.com)
                     (bcunning@nssi.com)