thalidomide: a sedative and hypnotic drug; withdrawn from sale after discovered to cause severe birth defects because it inhibits angiogenesis
teratogen: any agent that interferes with normal embryonic development: alcohol or thalidomide or X-rays or rubella are examples
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)