Kerr coined the term " opisthonephros " in 1919 . In 1949, Hyman wrote the opisthonephros has used up the mesomere tissue from which in amniotes both mesonephros and metanephros come . Some accounts call opisthonephros the mesonephros, but the opisthonephros in anamniotes ( lampreys, fish, and amphibians ) differ considerably than the mesonephros in amniotes ( reptiles, birds, and mammals ).
