Marine scientists are examining the deaths of 20 baby dolphins whose carcasses have washed ashore in Mississippi and Alabama this year in possible fallout from the Gulf of Mexico oil spill, researchers said Tuesday. The deaths, an unusually large number, are being studied as possible casualties of oil that fouled the Gulf of Mexico after a BP drilling platform exploded last April. The bodies of 20 infant and stillborn dolphins have been discovered since Jan. 20, most of them during the past week, on islands and beaches along a 130-mile stretch of coastline from Gulfport, Miss., east to Gulf Shores, Ala. That is about 10 times the number normally found in the two states during this time of the year, which is calving season in the region, said Moby Solangi, director of the Institute of Marine Mammal Studies in Gulfport.