ungulata: in former classifications a major division of Mammalia comprising all hoofed mammals; now divided into the orders Perissodactyla (odd-toed ungulates) and Artiodactyla (even-toed ungulates)
placental: mammals having a placenta; all mammals except monotremes and marsupials
dust bowl: a region subject to dust storms; especially the central region of United States subject to dust storms in the 1930s