A few doubts regarding Heart (Atrial) Embryology...

HI GUYS 

1. What is the developmental significance of both the Atrial appendages, i.e. what is the reason for their presence?  What I mean is, is it just to increase its volume as man has more oxygen and nutritional requirements all of a sudden in the developmental tree or what?

2. Why does septum spurium develop at all? It anyways is incorporated into the septum secondum... Or is it just a temporary embryological artifact seen in EM pics?

Also, is it that I can ask only 2 questions per topic? is there a thread where i can ask many more in the same post?

Thank You a lot for your help