Scientists believe that all life began in
the ocean, and that we are decendants
of fish. Over time animals crawled out of
the ocean and developed lungs to breath
on land. Many changes have occurred in
animals since that time. Humand have
body parts that they do not even need
any more, like an appendix
During the embryo stage
many animals look alike. It
is not until they are a fetus,
that you can tell them

Eventually a human will
develope a nose instead of
a snout like a dog or pig.
An embryo
becomes a
fetus when
all it's
organs and
features are
in place.
The limbs of these vertibrates first resemble fish-like buds. The eventually grow
into arms, legs and wings
After becoming a fetus, animals begin to
develope features that are specific to
that animal. During this time these
animals begin to excercise the muscles
of their lungs by breathing in and out
amniotic fluids