...the tails of embryos.
Embryos don't have tails. Suggest you study conception to birth development a little. The bone structure develops long before the fat is filled out. Thus the bones at the end of the spine, which will soon be surrounded by rear end fat, begin as an exposed area of bone. This, however, is not a tail. Nor was it ever a tail.
The lie – “The human embryo in one stage of development has a tail like a puppy.” This so-called “tail” is simply the coccyx, or the end of a person’s spine. As the embryo grows, the coccyx is covered with tissue and muscle so that it no longer shows, and is now nothing more than the end of the person’s spine. The coccyx serves as an anchor for useful muscles. Another lie by the evolutionists.
http://www.heritagebbc.com/archive3/0162.html (has refutations by a doctor of some other evolutionist lies as well)
http://home.primus.com.au/bonno/evolution5.htm -- shows the ridiculousness of anyone teaching or believing in the human 'tail' during its early developmental stages.