Before revision: Older sources, particularly before the 20th century, may refer to amniotes as " higher vertebrates" and anamniotes as " lower vertebrates", based on the antiquated idea of the evolutionary great chain of being.
After revision: Older sources, particularly before the 20th century, may refer to anamniotes as " lower vertebrates" and amniotes as " higher vertebrates", based on the antiquated idea of the evolutionary great chain of being.