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1 July 2022 Late Cretaceous Dimorphic Scaphitid Ammonoid Genus Yezoites from the Circum-North Pacific Regions
Kazushige Tanabe
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Abstract

Yezoites is a Late Cretaceous (Cenomanian–Campanian) small to very small dimorphic ammonoid genus belonging to the Scaphitidae, whose microconchs have a pair of long lateral lappets at the aperture. Based on examination of previously described material including type and figured specimens and newly recovered ones, five species of Yezoites are described herein from the circum-North Pacific regions (Japan, Sakhalin, Kamchatka, Alaska, Oregon, and California); i.e., Y. perrini (Anderson), Y. seabeensis (Cobban and Gryc), and Y. puerculus (Jimbo) from the Turonian, and Y. pseudoaequalis (Yabe) and Y. matsumotoi (Tanabe) from the Coniacian. Of these species, both microconchs and macroconchs are recognized in Y. puerculus and Y. pseudoaequalis, whereas only microconchs are known in the other three species. These Yezoites species characteristically occur in very fine-grained sandstone to silty mudstone facies suggesting an intermediate between nearshore and offshore environments, and can be used supplementarily for biozonation and correlation of the Turonian and Coniacian deposits in the North Pacific regions.

© by the Palaeontological Society of Japan
Kazushige Tanabe "Late Cretaceous Dimorphic Scaphitid Ammonoid Genus Yezoites from the Circum-North Pacific Regions," Paleontological Research 26(3), 233-269, (1 July 2022). https://doi.org/10.2517/PR200049
Received: 23 October 2020; Accepted: 13 January 2021; Published: 1 July 2022
KEYWORDS
Ammonoidea
Late Cretaceous
North Pacific
Scaphitidae
taxonomy
Yezoites
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