He grouped animals according to such criteria as mode of reproduction and possession or lack of red blood.
375 B.C. Theophrastus
He was Aristotle's pupil and he classified plants according to their uses and methods of classification.
18th Century Carolus Linnaeus
He worked on a system that would organize descriptive classification from the smallest of related groups up to the very largest. The system he developed, with revisions, is the basic system still used today.
18th Century Georges Cuvier
He grouped classes into phyla and incorporated both fossils and living species into the classification.