Percy Milton Butler (19 July 1912 – 7 February 2015)^[1] was a Britishzoologist andpalaeontologist. He proposed that dental characters are expressed in morphogenetic gradients along thedentition, which could therefore be used to study evolution. This became known as Butler's Field Theory. He was Professor of Zoology atRoyal Holloway, University of London, where he was the Head of the Department of Zoology from 1956 to 1972, and where he established the first course on mammalogy in the UK.

He was born on 19 July 1912 in Lewisham, London, son of a civil servant, Herbert Butler, and his wife Amy. As a child he was already interested in natural history. He graduated and did his PhD under supervision ofClive Forster-Cooper atPembroke College, Cambridge.

After receiving his undergraduate degree in 1933 Butler received Commonwealth Fund Fellowship to visitColumbia University in 1936. He studied fossil mammal teeth in various museum collections and was associated withWilliam King Gregory at theAmerican Museum of Natural History.^[2] He also collected fossil mammals, including a molar ofMegacerops. His study of fossil teeth brought him to consider the mechanics of teeth, which led to his field theory, published in 1939.^[3]

After appointments at Exeter and Manchester University, he joinedRoyal Holloway College in 1956. He retired at 60, and as an emeritus professor turned to full-time research, much of it done at theNatural History Museum, London.

Butler was an internationally recognised expert in the origins of early mammals from theMesozoic. He later got interested intertiary mammals from East-Africa and the fauna of theOlduvai Gorge, on which he worked withLouis Leakey. In his 80s he still worked on the early mammalian cladeHaramiyida.^[4]

Butler was awarded the American Geological Association’s Gold Medal. In 1986, he received the silver medal of the city of Paris. In 1994, he received and honorary membership of theSociety of Vertebrate Paleontology, and in 1996, received the society's prestigiousRomer-Simpson Medal.

Butler married Lillan Temple in 1941.^[5] He was a talented artist. His drawings feature in many of his publications andRoyal Holloway College held an exhibition of his watercolours.^[6]

• Tribute to Percy Milton Butler 1912–2015, J. Hooker (2017) Historical Biology, 30:1-2, 2-6,DOI: 10.1080/08912963.2017.1338518

• British palaeontologists
• 1912 births
• Academics of Royal Holloway, University of London
• 2015 deaths
• 20th-century British zoologists
• People from Lewisham
• Scientists from London
• British men centenarians

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