Stages in chick embryo development
Of course avians or birds hatch from eggs which are virtually self-contained life-support systems that only require warmth and oxygen to develop properly. Instead of an umbilical cord scar, birds have yolk sac scars at hatching. This is where the chick embryo is attached to the yolk sac.
But don’t look for any bird belly button rings. The scars usually heal and become virtually invisible.
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