In fetal life, the lungs are not expanded, so most of the blood from the right ventricle is shunted from the pulmonary artery to the aorta through the patent ductus arteriosus. With a few breaths the lungs expand, and blood flows from right ventricle to pulmonary artery into the lungs. Withdrawal of circulating prostaglandin from the mother plus bradykinins released from the expanding lung of the infant cause the ductus to close over a few minutes to hours. The closed ductus remains as the ligamentum arteriosum.
All of the above points are valid for fossils' contributions in understanding the process of evolution. They allow us to study the ancestry, we can see the homologous organs or structures, if fossils are well-preserved; different fossils can lead us to follow the cycles of the changes that occurred during macroevolutions, and fossils can be used to study different populations which had different body structures for surviving in different environmental conditions.
The two upper chambers are the atria or auricles. They are the left and right atriums
I would asy thd answer would be d if its not my bad .
