The significance of discovery of fossil species “Tiktaalik” to understand the history of evolution the lineage that gave rise to humans? ?

Answer 1

Not significant at all.  We already knew that vertebrate tetrapods had lobefin fish ancestors.  So someone found tiktaalik, a lobefin fish with a few tetrapod-like features.  Yay, goody.

Answer 2

I LOVE TIKTAALIK! What a cutie. Other transitional animals I like are Procynosuchus, Miacis, Caudipteryx and Pakicetus. My favorite is Miacis, because he's the last common ancestor of bears, cats, dogs and foxes.

SO CUTE!