A nostoceratid ammonoid Yezoceras elegans sp. nov. is newly described from the Coniacian of the Haboro area in Hokkaido, northern Japan. Yezoceras elegans sp. nov. having loosely coiled whorls, a wide umbilicus, and two prominent tubercle rows concentrated in the lower part of the whorls, is distinguished from the other species by these characteristics. Yezoceras elegans sp. nov. might have originated from Y. nodosum, judging from the stratigraphic correlation. The restricted occurrences of three Yezoceras species (Y. elegans sp. nov., Y. nodosum and Y. miotuberculatum) in Hokkaido, northern Japan suggest that the speciation of Yezoceras occurred in the northwestern Pacific realm during the Coniacian age.
How to translate text using browser tools
1 January 2021
A New Species of Yezoceras (Ammonoidea, Nostoceratidae) from the Coniacian in the Northwestern Pacific Realm
Daisuke Aiba,
Tomoki Karasawa,
Tetsuro Iwasaki
ACCESS THE FULL ARTICLE
Paleontological Research
Vol. 25 • No. 1
January 2021
Vol. 25 • No. 1
January 2021
Coniacian
Cretaceous
heteromorph ammonoid
Northwestern Pacific
Yezoceras