Uberon Homology note : Phylogenetic modifications within this basic pattern of arteries and veins are largely
correlated with functional changes. In the transition from water to land, gills gave
way to lungs, accompanied by the establishment of a pulmonary circulation. In some
fishes and certainly in tetrapods, the cardinal veins become less involved in blood
return. Instead, the composite, prominent postcava (posterior vena cava) arose to
drain the posterior part of the body and the precava (anterior vena cava) developed
to drain the anterior part of the body.[well established][VHOG];