Complex sentence: For years the only image of Bonney agreed on by scholars and historians to be authentic, the ferrotype survived due to a friend of Bonney, Dan Dedrick, keeping it following the outlaw's death.
Split into simpler sentences: For years the photo of Bonney was the only one agreed upon by scholars and historians to be authentic. The ferrotype survived due to a friend of Bonney, Dan Dedrick, keeping it following the outlaw's death.