vestigial animal features (thing)
See all of vestigial animal features
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Sat Nov 10 2001 at 0:29:34
Extra Toes in Horses and other
Horses are sometimes born with three-toed feet instead of a single hoof. Even when this does not happen, extra toe bones are often present in addition to the one supporting the hoof. In contrast, most fossil
s possess three-toed feet. Similar phenomena are observed in other ungulates such as cows, deer, and pigs.
Vestigial snake limbs
Snakes, especially boas, sometimes posses disconnected thigh-bones inside their bodies. Some snakes occasionally develop leg nubs which may aid in
. This suggests that snakes are descended from legged
s. Conversely, certain lizards such as the
Crabs possess small tails which are usually (but not always) folded under their abdomens. Many supposed fossil crabs have tails which trail behind them like lobsters and
Toenails on the fins of Manatees
toenails on their fins. These features serve no apparent purpose, but they suggest that ancesteral manatees could walk on land.
Ancestral insect wing configurations which reappear
Flies and roaches sometimes develop extra pairs of wings like their fossilized precursors.
have undersized wings. Often these wings are unused, or they are used only for display. Notable exceptions are
s and other
s: They use their wings as fins while swimming.
Mating of different solid-colored equids such as horses and
s sometimes produces offspring with stripes similar to
s'. This effect suggests vestigal stripe-producing genes in equids which only surface under special circumstances.
Hipbones in Whales
Some whales have hipbones which are attached to no limbs. These bones serve little purpose, but they may sometimes serve as an attachment point for muscles which support the sex organs in either sex.
These late-errupting teeth are the bane of many people because their jaws are too small to accept them. Some lucky people never develop them.
Unlike modern birds, which are all toothless, most bird fossils from the
Era possess teeth. In an experiment,
jaw tissue was grown beside mouse jaw tissue inside a mouse's eye. The chicken jaw produced conical teeth similar to the bird fossils'. This result indicates vestigal tooth-producing genes in chickens.
The Human Appendix
In the human
system, there is a small organ known as the
. Although unnecessary and generally useless, it does contain a cluster of
-producing cells similar to cells found in the
s. Like the tonsils, it can be safely removed.
Tails Which Reappear in Tailless Primates
Some humans (and other tailless primates) are sometimes born with vestigial tails. Like bears' tails, they are too small to be useful for anything.
Note to noders: Please attach any examples we have missed! Thanks!
Loren I. Petrich (firstname.lastname@example.org)
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