Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist — Any cow calf producer that has spent several years in the cattle business has had the experience of assisting a cow or heifer deliver a calf that was coming backwards. Research from the Ft. Keogh experiment station in Montana with over 13,000 calvings in 15 years suggests that 1.6% of all deliveries were backwards (Patterson, et al.,1987 Therio. vol 28 no. 5). Understanding the physiology and anatomy of the calf and mother will improve the likelihood of a successful outcome. Study the diagram of the “posterior presentation” shown below.