image credit http://picssr.com/tags/copalingalodge/page4
All tinamou are from the family Tinamidae, and in the larger scheme are also ratites. All ratites evolved from prehistoric flying birds, and tinamous are the closest living relative of these birds.
image credit http://www.hbw.com/ibc/species/pale-browed-tinamou-crypturellus-transfasciatus
The grey tinamou has several subspecies