Overview Dr. David Arthur Otto’s Ph.D. dissertation for the University of Missouri is a study of the Middle Pennsylvanian coal ball petrifactions found in Cherokee County, Kansas. The study examines three hundred coal balls, revealing 26 genera of plants. The flora examined by Dr. Otto reveal that the site of his study was a swamp during the Middle Pennsylvanian Period. This Ph.D. dissertation identifies a number of previously unidentified Kansas coal ball flora as well as compares Middle...