Taxonomy thumb|An Amazon river dolphin as depicted in Brehms Tierleben, 1860s The species Inia geoffrensis was described by Henri Marie Ducrotay de Blainville in 1817. Originally, the Amazon river dolphin belonged to the superfamily Platanistoidea, which constituted all river dolphins, making them a paraphyletic group. Today, however, the Amazon river dolphin has been reclassified into the superfamily Inioidea. There is no consensus on when and how their ancestral species penetrated the Amazon basin; they may have done so during the Miocene from the Pacific Ocean, before the formation of the Andes, or from the Atlantic Ocean.
Taxonomy thumb|An Amazon river dolphin as depicted in Brehms Tierleben, 1860s The species Inia geoffrensis was described by Henri Marie Ducrotay de Blainville in 1817 Originally, the Amazon river dolphin belonged to the superfamily Platanistoidea, which constituted all river dolphins, making them a paraphyletic group. Today, however, the Amazon river dolphin has been reclassified into the su.perfamily Inioidea. There is no consensus on when and how their ancestral species penetrated the Amazon basin; they may have done so during the Miocene from the Pacific Ocean, before the formation of the Andes, or from the Atlantic Ocean.