A Florida man was arrested this week after a dog he adopted just days earlier was found decapitated and wrapped in a plastic bag in park, authorities said. The Pinellas County Sheriff’s Office said deputies responded to a report of a deceased dog wrapped in a plastic bag in the area of East Beach at Fort Desoto Park, south of St. Petersburg on Mullet Key, at around 6:45 p.m. on Tuesday. Deputies arrived to find “a male bulldog mix with its head decapitated, floating in the mangroves.” The dog was implanted with a microchip, which was scanned by Pinellas County Animal Services, revealing him to…