The priestly, aristocratic party — they held the temple, accepted only the five books, and denied the resurrection.
The Sadducees were the establishment: wealthy, priestly, and running the temple and much of the council. They took only the Torah as authoritative and, on that basis, rejected resurrection, angels and spirits — which Luke notes in a parenthesis to explain why an argument in Acts split the room. Their question to Jesus about the woman with seven husbands is a resurrection puzzle designed by people who did not believe in one. When the temple fell in AD 70 they had nothing left to stand on, and they disappear.