Theropods from these formations include genera of tyrannosaurids, ornithomimids, troodontids, avialans, caenagnathids, and dromaeosaurids. "Acheroraptor" and "Dakotaraptor" are dromaeosaurids from the Hell Creek Formation. Indeterminate dromaeosaurs are known from other fossil formations. Common teeth previously referred to "Dromaeosaurus" and "Saurornitholestes" later were considered to be "Acheroraptor". The tyrannosaurids from the formation are "Nanotyrannus" and "Tyrannosaurus", although the former might be a junior synonym of the latter. Among ornithomimids are the genera "Struthiomimus" as well as "Ornithomimus"; an undescribed animal named "Orcomimus" could be from the formation. Troodontids are only represented by "Pectinodon" and "Paronychodon" in the Hell Creek Formation; with a possible species of "Troodon" from the Lance Formation. One species of coelurosaur is known from Hell Creek and similar formations by a single species, "Richardoestesia". Only three oviraptorosaurs are from the Hell Creek Formation, "Anzu", "Leptorhynchos" and a giant species of caenagnathid, very similar to "Gigantoraptor", from South Dakota. However, only fossilized foot prints were discovered. The avialans known from the formation are "Avisaurus", multiple species of "Brodavis", and several other species of hesperornithoforms, as well as several species of true birds including "Cimolopteryx".