Darryl Dawkins, who arrived in professional basketball as a gigantic teenager and became one of the game’s fiercest dunkers and most notoriously lovable characters, a backboard-smashing, referee-dissing, fun-loving manchild known to fans as Chocolate Thunder from Planet Lovetron, died on Thursday in Allentown, Pa. He was 58.One of basketball’s larger-than-life figures — though at 6-foot-11 and more than 250 pounds he was pretty large to begin with.Selected as an 18-year-old from Orlando, Fla., by the Philadelphia 76ers as the fifth overall choice in the 1975 National Basketball Association draft, he became the first player to make the leap directly from high school to the N.B.A. (He was not the first high schooler to turn pro. A year earlier, Moses Malone had jumped from high school in Virginia to the Utah Stars, a franchise in the American Basketball Association, which merged with the N.B.A. in 1976.