FLIGHTLESS
BIRDS – WINGS?
• Some mammals moved back into water ~ 50
mya
• A mammal was the ancestor of the modern
whale
• Despite uselessness, evolution left traces of
hind legs behind - these vestigial limbs can
still be seen modern whales
• Many cases of whales with rudimentary hind
limbs (Baleen, humpback, and some of sperm
whales)
• Most examples only leg bones – some
included feet with complete digits
• These fused vertebrae are the only
vestiges that are left of a tail that other
mammals still use for balance,
communication, and in some primates, as
a prehensile limb
• As our ancestors were learning to walk
upright, their tail became useless, and it
slowly disappeared
Wisdom Teeth
• jaws are smaller now
• In the past, it might be common to
have lost several, probably most, of
his teeth - incoming wisdom teeth
would prove useful
• Dandelions reproduce without fertilization
• They basically clone themselves quite
successfully
• Look at any lawn – if they reverted to sexual
reproduction, they might not retain whatever
traits they have that allow them to be pests to
gardeners everywhere
• Asexual reproduction can be a good strategy
in an environment that is constant if a
species is well suited to those conditions
Fake Sex in Virgin Whiptail
Lizards (Vestigial Behavior)
• Only females exist • females don’t need
in some species of
the males
lizards
• They produce by
parthenogenesis
(an unfertilized egg
develops into a
new individual)
• Male nipples are “vestigial” – but are not truly
vestigial because they are not remnants of
functional male nipples in ancestral species.
• They occur because nipple precursors are
grown early in the development of the human
embryo, before sexual differentiation.
• The navel, too, is a by-product of embryonic
development rather than an evolutionary
vestige.
• In plant-eating vertebrates, the appendix is
much larger and its main function is to help
digest a largely herbivorous diet.
• The human appendix is a small pouch
attached to the large intestine where it joins
the small intestine and does not directly
assist digestion.
• Biologists believe it is a vestigial organ left
behind from a plant-eating ancestor.
• Snakes are known to be the descendants of
four-legged reptiles.
• Most pythons (which are legless snakes)
carry vestigial pelvises hidden beneath
their skin. The vestigial pelvis in pythons is
not attached to vertebrae (as is the normal
case in most vertebrates), and it simply
floats in the abdominal cavity.
• Some lizards carry rudimentary, vestigial
legs underneath their skin, undetectable
from the outside
• Boa constrictors, which are
descended from four-legged reptiles,
grow tiny hind legs