Psittacosaur tail structures

["Ken Kinman" <kinman@hotmail.com>]

Gunter,
    This is the first I've heard of these structures on the tail of 
Psittacosaurs.  How did I miss this?  Oh well, sounds very interesting and 
thought provoking.
    Anyway, it fits in very nicely with my hypothesis that protofeathers 
began on the tails of dinosaurs and then spread forward on the body in their 
descendants and later became exapted for thermoregulation (incl. brooding).  
I think aerodynamic feathers came even later (even wing feathers would have 
been initially thermoregulatory, as favored by Tom Hopps and others).
    The purpose of this integument on just the tail would presumably be 
predator evasion (diverting attention to a relatively expendable end of the 
tail).  If this stage occurred in early dinosauromorphs, it would perhaps 
make balancing problems (brought up by Jaime Headdin) from loss of part of 
the tail even less of a problem for my hypothesis.  Such a predator evasion 
strategy would have worked especially well in forms that had long slender 
tail tips (wiggly, but with little mass).
           ----Ken Kinman
P.S.  Psittacosaurs could represent the brooding thermoregulatory stage if 
they had this integement on the posterior abdomen.


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