Sentence:  The skull ended up as Dubois' personal <WSD>Waterloo</WSD>. His work received nothing but rejection and derision throughout the next decade, and the bones became dark secrets for much of the early twentieth century, locked away in Dubois' home, unavailable for study by other scholars. 
Meaning of the word marked with <WSD> tags:  "Often in the term" '''(meet one's Waterloo)''': a notable and decisive defeat following an encounter with a powerful opponent or a problem that is too difficult.