Andreas Vesalius

(1550)- Comparative Anatomy, observing human anatomy

William Harvey and William Paley

(1600's)- Observation and natural theology, blood was pumped from heart through body

Nicholas Steno

(1666)- Fossils and the birth of paleontology, law of superposition

Carolus Linneas

(1735)- Nested hierarchies, the order of nature, system of classification

Georges-Louis Leclerc, Comte de Buffon

(1700's)- Old earth, ancient life

Thomas Malthus

(1800)- The ecology of human populations

Georges Cuvier

(1795)- Extinctions and catastrophe, leading expert on the anatomy of animals

Jean Baptiste Lamarck

(1793)- Early concepts of evolution

Karl Von Baer

(1828)- Developmental similarities

William Smith

(1800)- Biostratigraphy, dating rocks using fossils

Charles Lyell

(1830)- Uniformitarianism/uniform processes of change

Gregor Mendel

(1850's)- Discrete genes are inherited

Charles Darwin and Alfred Russel Wallace

(1859)- Natural selection

Earnest Haeckel

(late 1800's)- Early evolution and development

Wallace and Wegener

(1848)- Biogeography

Thomas Huxley and Eugene Dubois

(1857)- Fossil hominids, human evolution

Thomas Hunt Morgan

(1900)- Chromosomes, mutation, and the birth of modern genetics