879. COMPARATIVE MORPHOLOGY OF NIPPONITES AND EUBOSTRYCHOCERAS (CRETACEOUS NOSTOCERATIDS)

DOI Web Site 1 Citations

Bibliographic Information

Other Title
  • 879. 北海道上部白亜系蝦夷層群より産する, ノストセラス科異常巻きアンモナイト
  • 北海道上部白亜系蝦夷層群より産する,ノストセラス科異常巻きアンモナイト〔英文〕
  • ホッカイドウ ジョウブ ハクアケイ エゾソウグン ヨリ サンスル ノストセラス

Search this article

Description

Nipponites and Eubostrychoceras, Late Cretaceous nostoceratid ammonites, seem to be closely related to each other as recognized from the similar shell surface sculpture and early shell morphology. As the result of detailed comparison of their shell morphology and stratigraphic occurrence, six discrete morphotypes were recognized by the shell surface ornamentation and mode of coiling as well as their ontogenetic change. Both of Nipponites and Eubostrychoceras slightly and stepwise changed their form with the time. Morphotype A, the most primitive form of Nipponites, shares many diagnostic characters with the coexistent Morphotype F of Eubostrychoceras, although there is a clear difference in the coiling pattern after their early growth stage. A saltatory evolution from Eubostrychoceras to Nipponites (meandrous form) is strongly suggested not only by theoretical aspect but also by empirical evidence.

Journal

Citations (1)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top