Evolution. Evidences.

 http://es.scribd.com/doc/94214348/Evolution-2012
   
http://es.scribd.com/doc/94214861/pruebasevol2012

 Panda's fore limbs, pentadactilled, have an extra opposable finger, called the "Panda's thumb". It is none but a sesamoid bone modification that Pandas use for grabbing and tearing bambu stems.
Point out the fact that there are two species of Panda, Gigant panda (Ailuropoda melanoleuca) and red panda (Ailurus fulgens), and both have the sixth thumb, but the common ancestor of both that lived 35 mill years ago did not have it. Try to give a reason for this.

Natural and sexual selection:

http://birdsofparadiseproject.org/content.php?page=111