| Comment: | A single large specimen, approximately 10 cms. in diameter, slightly distorted and compressed laterally, is referred to Daubichites. The only Lower Permian family having this sort of 8-lobed suture is the Paragastrioceratidae. A single constriction is preserved, which shows shallow lateral and ventral sinuses. Presence of a ventral sinus eliminates Uraloceras. Lack of ribs or nodes on the umbilical shoulder in the adult eliminates Paragastriocera from consideration and absence of longitudinal ridges eliminates Altudoceras and Strigogoniatites. This leaves Pseudogastrioceras and Daubichites, and the whorl of the first-mentioned is narrower, the shell being more compressed. Daubichites has spiral sculpture on the surface and umbilical riblets in young shells, but these cannot be determined from this poorly preserved specimen. But the only other thing it resembles is Pseudoparalegoceras, an Early to Middle Pennsylvanian genus of a different stock. The popanoceratid accompanying it is referred to Peritrochia Girty. All of the American forms formerly known as Marathonites are now included in Girty’s genus. There is some difference in the sutures and shell coiling in this group and accordingly Ruzhencev (1956, Paleontologicheskii institut trudy, tom 60, p. 237-249) in his study of Artinskian ammonioids recognizes four genera with this kind of suture in the Marathonitidae: Kargalites, Tabantalites, Marathonites, and Peritrochia. Following Ruzhencev’s classification, the Alaska species has a suture closest to that of Kargalites typicus Ruzhencev. The prongs of the ventral lobe are bifid but show third order dentition as does the first lateral lobe, the next two lateral lobes are trifid and the fourth appears undivided and narrow. So far as I can recall, all of the previously described marathonitids from the United States have non-digitate prongs in the ventral lobe, so this form is more like several described previously from the U.S.S.R. So far as age is concerned, Kargalites ranges through beds of Zhigulaevian to Artinskian in age. Ruzhencev described none from the Sakmarian, however, K. typicus Ruzhencev is characteristic of the Aktastian Substage of the Artinskian Stage. I would not, however, rule out the possibility of there being similar forms in Sakmarian equivalents. |