Why giraffes will become short again?

Elephants, rhinos, kangaroos, camels, all mammals evolved at the first time by small bulk animals. Mammals have managed to overcome gravity by the aid of 4-chambered hearts and strong blood circulatory systems and making their bulks larger. But during the time a gradual increasing of gravity occurred, mammals failed against greater gravity and had to minimize their bulks. The process of minimizing the body size has continued up to now and will continue in the future Mammals will become gradually smaller. All mammals after its peak again become smaller. But as you can see the peak point have been located them at different times. The peak of elephants, rhinos, kangaroos and camels has been located in the past. This means that they have been started to smaller become in the past. But the peak of giraffe has been located in present tense. This means that giraffes will becomes smaller in the future. This book dedicate to: Giordano Bruno, Bertrand Russell, Samad Behrangi and all scientists before me.