English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The Devonian nautiloids Hercoceras Barrande, 1865 and Ptenoceras Hyatt, 1894 are closely related and should be classified within the single oncocerid family of Hercoceratidae Hyatt, 1884, which has priority before the family Ptenoceratidae Teichert, 1939. This is supported particularly by the similarity of their embryonic shell and by the character and ontogeny of ventrolateral outgrowths. The intraspecific variability of shells in Hercoceras mirum Barrande, 1865 (Lower Devonian, Prague Basin, Czech Republic) is striking and unusual among nautiloids. The variability in Ptenoceras alatum (Barrande, 1865) is also high, demonstrating fluent transitions between individual morphotypes. Therefore, the other two species of this genus described from the Pragian Stage of the Prague Basin, Ptenoceras modicum (Barrande, 1877) and Ptenoceras barrandei Zhuravleva, 1974 should be assigned to the single species Ptenoceras alatum

Systematic position and variability of the Devonian nautiloids Hercoceras and Ptenoceras from the Prague Basin (Czech Republic)