Re: Parasaurolophus

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

>From: binder@zk3.dec.com (vitam gustare)
 > 
 > My question stands.  How do we KNOW that the larger-crested specimens
 > are male?  I understand that we can base guesses on similarities with
 > extant species of birds or reptiles, but what is there that makes the
 > supposition more than supposition?
 > 
As a general rule, one is never 100% sure of anything in science.

Still, in the case of Corythosaurus, the specimen series is quite
large, and shows a pattern of variation with two distinct adult
crest forms in a single geographical area over the same span of
time.  Since the two adult forms are too similar in size and morphology
to allow them to coesxist without competing - and since in competition
one form almost always eliminates the other in any given area -
the conclusion that they are all one species is quite sound.
Given that sort of a bimodal distribution of morphs in a *single*
species, the only reasonable conclusion is sexual dimorphism.
Under those circumstances, it is almost always the male that is
more gaudy - more display oriented.  Ergo, the large-crested forms
are males.

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

The peace of God be with you.