The cause was complications of scleroderma, a chronic disease of the connective tissue, her family said. Ms. Cosman, who moved to California in the late 1990's, was for decades a resident of Tenafly, N.J.
A longtime faculty member at the City College of New York, Ms. Cosman founded the Institute for Medieval and Renaissance Studies there in 1968 and was its director for many years. The institute closed in 1993, when Ms. Cosman retired. In the 1970's and afterward, she helped organize the annual medieval festival at the Cloisters in Upper Manhattan and spoke frequently at the Metropolitan Museum of Art and elsewhere about daily life in the Middle Ages.
The author of nearly a dozen books, Ms. Cosman was best known to popular audiences for "Fabulous Feasts: Medieval Cookery and Ceremony" (George Braziller, 1976). An illustrated study of culinary practice in the Middle Ages, it also included recipes for dishes like roseye (fried fish in a rose-petal sauce), mulled wine and peppermint rice.
Ms. Cosman took her work seriously. She could sing madrigals, play the lute and eat with her fingers off a trencher in the proper medieval style. Her house in suburban New Jersey was appointed with ornately carved period furniture. Arms and armor lay about, the walls were hung with Flemish tapestries, and the cellar was stocked with mead.
On special occasions, visitors might find Ms. Cosman, wearing a flowing velvet gown, presiding over an elegant table that could include blankmangere en doucette (chicken cooked with cumin and cream, served in pastry) and lentil mawmenye (a lamb and lentil stew). Utensils were not supplied.
Apart from medieval food and birthday cake, the only thing Ms. Cosman knew how to cook was hamburger, a dish that took her nearly 15 years to master. Her family was fond of hamburger, which was always served by candlelight.
Ms. Cosman could also play the piano, fly an airplane and shoot a gun. In the 1980's and early 90's, she made her living buying and selling medical practices, and in the mid-90's, when she was in her late 50's, she became a lawyer. In recent years, she worked as a health-care policy analyst and was a volunteer patrolwoman with the San Diego County Sheriff's Department.
At her death, Ms. Cosman was a member of the board of the California Rifle and Pistol Association. She was also on the board of the Wake Up America Foundation, which opposes illegal immigration, and was frequently heard discussing the issue on talk radio.
Madeleine Pelner was born in Brooklyn on Dec. 4, 1937, the oldest of three daughters of Louis Pelner and the former Lillian Rosen. She received a bachelor's degree from Barnard in 1959, a master's from Hunter in 1960 and a Ph.D. in English and comparative literature from Columbia in 1964. In 1995, she earned a law degree from the Benjamin N. Cardozo School of Law at Yeshiva University.
As a Jewish child growing up during World War II, Madeleine was acutely conscious of the need for self-protection, something she later discussed in interviews. As a young woman, she learned to shoot. If the knock on the door were to come, Madeleine Pelner would be ready. By the time she was in college, her devotion to the concept of personal responsibility had led her to the writings of Ayn Rand, whose libertarian ideas she embraced.
Ms. Cosman's diverse work was united by her interest in the history of medicine. As a scholar of medieval medicine, she found that early medical treatises often included descriptions of food thought to be curative. This led to "Fabulous Feasts." She was later the founder and president of Medical Equity, a brokerage of medical and surgical practices.
Most recently, Ms. Cosman's interest in health care policy led her to study the effects of illegal immigration on the United States health-care system. Her article "Illegal Aliens and American Medicine," published last year in The Journal of American Physicians and Surgeons, has been widely reproduced on anti-immigration and other conservative Web sites.
Ms. Cosman's husband, Bard, a plastic surgeon whom she married in 1958, died in 1983. Survivors include a daughter, Marin, of Scarsdale, N.Y.; a son, Bard, of La Jolla, Calif.; and four grandchildren. Information on other survivors could not be confirmed.
Ms. Cosman also leaves behind a vast library of illuminated manuscripts and a large collection of handguns.