Equss is a genus of the family Aratidecthidae, an extinct order of mantis shrimp-like crustaceans which lived in the Mississippian subperiod in what is now Montana, in the order Aeschronectida.
Equus is a genus of mammals in the family Equidae, which includes horses, donkeys, and zebras. Aeschronectida is an extinct order of mantis shrimp-like crustaceans which lived in the Mississippian subperiod in what is now Montana. Aeschronectida
Schram, 1969 
