Which is not a vessel that brings blood directly into the right atrium?

Coronary Sinus does not transport blood directly into the right atrium.

Explanation:

"Coronary sinus" is a group of veins joined collectively to form a big vessel that accepts blood from the myocardium. It is positioned along the heart's posterior surface between the left ventricle and left atrium. The outline of the vein is larger than normal and is huge enough to enable blood to be collected by most veins that enter the heart. The coronary sinus receives the maximum of the cardiac venous blood. It releases blood with less oxygen to the right atrium, like how "superior and inferior venae cavae" does. It is found in "mammals", including humans.