a chicken egg is about 50g :)

yes because the chicken is inside of the egg.if the chicken wasnt it would be called just an egg

the egg because dinos lay eggs

seagull's eggs are about the size of an average chicken egg to 2x the size.

From an evolutionist's point of view, the egg came first. A chicken, by definition, must be born from an egg. The egg does not have to be a chicken's egg however. The egg could be layed by an avian that is very similar to a chicken, but which is not a chicken. A small mutation in the genes produces the chicken offspring, which in turn lays eggs to produce more young.