Can you solve this riddle?

I have a riddle and the first person to answer it right will get 50% of my next riddle post which I will be posting when I get the answer for previous one.

Here is the riddle

What creature walks on 4 legs in the morning, two legs at noon, and three legs at night?

My second Riddle Post http://www.sharenator.com/Riddle_me_this_My_second_riddle_post/