Palaeotetrix gilli Shufeldt, 1891. is a Nomen Nudum.
But Palaeotetrix gilli Shufeldt, 1892, now Dendragapus gilli (Shufeldt, 1892) is as far as I know a valid species with holotype AMNH 3474 a right carpometacarpus, referred material UMMP 48233 complete carpometacarpus.
Jehl, 1967 made the new combination Dendragapus gilli (Shufeldt, 1892).
In 1969 Jehl even described the new subspecies Dendragapus gilli milleri Jehl, 1969 (Holotype UCMP 82977 a left carpometacarpus.
Etymology: the speciesname is named in honour Shufeldt's friend, Dr. Theodore Gill, the distinguished American naturalist and ichthyologist.
milleri is named after Alden Holmes Miller (4 feb 1906-9 oct 1965) (I suppose, I haven't seen the description), the famous paleornithologist from California.
The species is from the Late Pleistocene of North-America, California, Shasta County, Samwel Cave
Hope I answered your question,
Fred