A man believed to be in his late 20s was fatally shot in Dorchester Wednesday night, police said. Boston police said the shooting occurred at about 9:45 p.m. near 70 Ames St. The man was taken to Boston Medical Center, where he was later pronounced dead, the statement said. Police did not identify the victim. Anyone with information on the shooting is urged to call homicide detectives at 617-343-4470 or the department’s anonymous tip line at 800-494-TIPS.