Organs in a rudimentary condition plainly show that an early progenitor had the organ in a fully developed condition, and this in some cases implies an enormous amount of modification in the descendants.
Aztarna-egoeran dauden organoek argi erakusten dute antzinako arbaso batek oso-osoan garaturik izan zuela organo hori, eta honek, kasu batzuetan, ondorengoengan eraldaketa pilo eskerga izan dela inplikatzen du.