Placentals
by Emily O.
Placentals are a clade of animals that evolved an organ called a placenta inside the embryo. This organ gives the baby more nutrients and disposes of waste. This strengthened babies of animals who had evolved this trait, and it gave animals the ability to give live birth instead of laying eggs. Human beings are placentals as well, and without the placenta, we would still be laying eggs. Three animals that have a placenta are the anteater, rabbit, and whale.
Last updated April 9, 2007.