He was the son of farmers Elmer and Edith Arnold. Arnold's family moved to
Ludlowville, New York, and he attended
Cornell University with the intent to study
agriculture. Interaction with
Loren Petry, a Cornell professor studying
Devonian plants of the region, lead to Arnold shifting his focus to
paleobotany. He received his Bachelor of Science in 1924, his Ph.D. in 1929 with his
thesis on Devonian megafloral paleobotany. He started working at the faculty of botany,
University of Michigan from 1928 and became curator of the collection of fossil plants in 1929. Arnold became a professor in 1947. He maintained close relations with researchers in India, being a friend of
Birbal Sahni, of the
Birbal Sahni Institute of Palaeobotany and served his year in residence from 1958 to 1959 at the institute. Arnold was a member of many learned societies and was the author of the
Introduction to Paleobotany published in 1947. ==Research==