H. montana was named by Shufeldt in 1915, and while its known material (a single dorsal vertebra) cannot be directly compared to H. altus, Shufeldt and others have considered it distinct due to its apparently smaller size.
Vrsti H. montana je naziv 1915. godine dao Shufeldt, i mada se njen jedini poznati ostatak (jedan leđni kralježak) ne može direktno usporediti sa H. altus, Shufeldt i ostali smatraju je odvojenom vrstom zato što je manja.