Dre Greenlaw lowered his helmeted head and headbutted Ernest Jones, sending the Seattle Seahawks linebacker looking for a towel to wipe away the blood on Sunday. And less than 24 hours later, the NFL dropped the proverbial hammer on Greenlaw.Greenlaw, a San Francisco 49ers linebacker, has been suspended for one game, the NFL announced Monday.The suspension is without pay.49ERS LINEBACKER DRE GREENLAW HITS SAM DARNOLD OUT OF BOUNDS THEN HEADBUTTS ERNEST JONES ALONG SEATTLE SEAHAWKS BENCHGreenlaw was penalized for unsportmanlike conduct when he hit Seahawks quarterback Sam Darnold as he was going out of bounds along his team's sideline during Sunday's game.Things got uglier when Greenlaw was surrounded by Seahawks players, Jones stepped up to him despite not wearing his helmet, and then Greenlaw headbutted Jones.Greenlaw will be eligible to return to the 49ers active roster on Oct. 20, following his team's Oct. 19 game against the Washington Commanders.Greenlaw may appeal the suspension under the collective bargaining agreement but there is not yet any indication if he will do that. If he goes that route, the appeal would be heard by a hearing officer – either Derrick Brooks, Jordy Nelson, Ron Rivera or James Thrash.NFL REFEREES JEFF SEEMAN AND ADRIAN HILL SUSPENDED AFTER UNPROFESSIONAL CLASHES WITH PLAYERS IN WEEK 4All the hearing officers are former NFL players.ZERO BS. JUST DAKICH. TAKE THE DON'T @ ME PODCAST ON THE ROAD. DOWNLOAD NOW!OutKick reported on Sunday that a fine or suspension or both was in the cards for GreenlawGreenlaw has a history of becoming emotional. And getting fined. And even suspended. In 2023, Greenlaw was ejected following a sideline altercation with Philadelphia Eagles head of security Dom DiSandro during another incident along the opponent's sideline.The 49ers have had their share of suspensions this season with owner Jed York currently serving a league suspension for violating the personal conduct policy after he was arrested in a prostitution sting in Ohio.NFL SUSPENDS AND FINES 49ERS OWNER JED YORK FOR VIOLATION OF CONDUCT POLICY TIED TO PROSTITUTION ARRESTThat history, when considered together, paints Greenlaw as something of a hothead.FOLLOW ARMANDO SALGUERO ON X: @ARMANDOSALGUERO