 It is unclear how many species of Allosaurus there were . Eight species have been considered potentially valid since 1988 ( A. amplexus , A. atrox , A. europaeus , the type species A. fragilis , the as @-@ yet not formally described " A. jimmadseni " , A. <unk> , A. maximus , and A. tendagurensis ) , although only about half are usually considered valid at any given time . There are also at least ten dubious or undescribed species that have been assigned to Allosaurus over the years , along with the species belonging to genera now sunk into Allosaurus . In the most recent review of basal tetanuran theropods , only A. fragilis ( including A. amplexus and A. atrox ) , " A. jimmadseni " ( as an unnamed species ) , and A. tendagurensis were accepted as potentially valid species , with A. europaeus not yet proposed and A. maximus assigned to Saurophaganax . 
