The common pelecypod in these collections from northern Alaska belongs to the genus Otapiria (see memos of Oct. 26, 1964 and Jan. 29, 1965 to N.J. Silberling) and is similar in size, shape and ribbing to O. limaeformis Zakharov from northeastern Siberia. It differs by having distinct ribbing on its right valve, whereas the right valve of the species from Siberia is smooth.

The two ammonites from locs. 65ATr123B and 65ATr149.4 are highly evolute and have strong, straight radial trending, widely spaced ribs. The specimen from loc. 65ATr123B may have a low keel on its venter. These ammonites resemble genera that are fairly common in Lower Jurassic beds and in basal Middle Jurassic beds. In side view they resemble such genera as Tmetoceras from the basal Bajocian and Catulloceras and Dumortieria from the upper Toarcian, which genus has a sulcus on its venter.

One bit of evidence against an early Bajocian age for the Otapiria-bearing beds is the presence of a well preserved specimen of Oxytoma (loc. 65ATr73.5) that does not belong to O. jackonsoni (Pompeckj). That species occurs in basal Bajocian beds on Prince Patrick Island (Frebold, 1957, Geol. Survey Canada Bull. 41, p. 14, 23, pl. 6, figs. 1-3) and on the Canning River (Mes. loc. 24035).

One bit of evidence against a Toarcian age for the Otapiria beds is the presence of Inoceramus similar to I. lucifer Eichwald, which species at Wide Bay in the Alaska Peninsula and in the Cook Inlet region ranges through beds that are correlated with the early Bajocian and early middle Bajocian of Europe on the basis of ammonites. Similarly in Japan Inoceramus similar to I. lucifer occurs in beds of Bajocian age (Hayami, 1960, Jour. Fac. Sci., Univ. Tokyo, Sec. II, vol. 12, pt. 2, p. 292.)

An age not older than Toarcian for the Otapiria beds is shown by the fact that true Inoceramus is present. This genus according to Hayami (1960, p. 292, 294) originated near the end of the Early Jurassic time and became common in the Bajocian.

In summation, the ammonites present in the Otapiria beds indicate an Early Jurassic or early Middle Jurassic age. The specimens remind me of genera that occur near the Toarcian-Bajocian boundary. The presence of true Inoceramus shows that the beds are not older than Toarcian. This resemblance of the Inoceramus to I. lucifer Eichwald favors an early Bajocian age. Possibly the Otapiria-beds span the Toarcian-Bajocian boundary.

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Brief statement of problem and remarks (from collector):
Collector(s) & year(s): Tailleur, Donnell, 1965

[Note by R.B. Blodgett: locality descriptions combines data from E&R report (by Jones) and Request for Examination of Fossils sheet (submitted by Tailleur)]