| Comment: | The Alaskan specimens from the first two collections listed, based upon surface sculpture and shape alone, can belong to either of two genera. The choice lies between Artinskia Karpinsky, 1926 and Synartinskia Ruzhentsev, 1939. The Treatise on Invertebrate Paleontology regarded them as synonyms. Nassichuk (1970, Jour. Paleontology, v. 44, no. 1, p. 80) however, recognized Synartinskia in the Canadian Arctic in beds probably of late Artinskian age. I have favored Artinskia in this identification because it is the older name and because the relatively long, low slanting nodelike ribs on the ventro-lateral shoulders are very similar to those in Artinskia falx (Eichwald), the type species of Artinskia. Lacking the suture, however, a positive identification can not be made. Artinskia ranges from late Orennurgian (latest Upper Carboniferous) in the U.S.S. R. through the Early Permian Artinskian Stages Synartinskia is found in rocks of the Sakmarian and Artinskia Stages. Uraloceras ranges from the early Sakmarian Stage through the Baigendzhinia Substage of the Artkinskian (Nassichuk, Furnish, and Glenister, 1965, Geol. Survey Canada Bull. 131, p. 20). It occurs in the Canadian Arctic and in Alaska (Nassichuk, Furnish, and Glenister, 1965 op. cit., p. 20; Nassichuk, 1971, Jour. Paleontology, v. 45, no. 6, p. 1015), but is most common in the Ural Mountains. Daubichites is restricted to the Early Permian (Sakmarian and Artinskian Stages); most of the Phosphoria pseudogastriocerids are referabble to this genus (Nassichuk, 1970, op. cit., p. 81-84). Based on these facts, I would suggest that an Early Permian (Sakmarian or Artinskian age for the higher beds of the type Mankomen Formation is very likely, but the lower occurrence of Artinskia?, unsupported by other evidence may be either Early Permian or very late Carboniferous. |