Given an example of a structure that is present in human embryos, but has disappeared by birth.

Gills and tail

Explanation:

1. Embryos of many different animals, like mammals, birds, fish, etc. they look very similar to each other in starting in the embryo stage.

2. In starting, recognizing them as of different animal is very difficult.

4. There are some similar characters which are found in various species, For example, fish and human embryos both have gill slits. In case of fish, gill slits develop into gills when fish get mature, and in case of humans they disappear before birth.

Gills, tail in human disappear as the embryo grows.

Human embryo have gills and tail but by the time of birth both of this disappears.

Explanation:

At the development process of the human embryo, at some stage, it consist of gills and tail. At some stage, their body possesses folded neck structures (gills like the fish do) which during the development process become our jaws. The human embryo also possesses a tail at the very beginning. But during the development and maturation period, this also gets obsoleted.