hamitoconic

English

Fossil shell of a Polyptychoceras ammonite, which is hamitoconic.

Adjective

hamitoconic

1. (malacology, of a shell or fossil) Having a shell which has two or more straight shafts, like some heteromorph ammonites such as Polyptychoceras.
   • 2014, AI Arkhipkin, “Getting hooked: the role of a U-shaped body chamber in the shell of adult heteromorph ammonites”, in Journal of Molluscan Studies:

     Juveniles had virtually all possible types of coiling of their shells, ranging from regular planispiral and orthoconic to torticonic, hamitoconic and gyroconic.

   • 2015 July 22, Christian Klug, Dieter Korn, Kenneth De Baets, Isabelle Kruta, Royal H. Mapes, Ammonoid Paleobiology: From anatomy to ecology, Springer, →ISBN, page 4:

     ... hamitoconic, orthoconic, scaphitoconic, torticonic and vermiconic.

   • 2019 October 15, George R. McGhee, Jr., Convergent Evolution on Earth: Lessons for the Search for Extraterrestrial Life, MIT Press, →ISBN, page 149:

     ... hamitoconic heteromorphs grew shell forms that started out orthoconic but then underwent a sharp 180-degree turn such that the next growth stage of the animal was straight, but parallel to the original orthoconic section and growing in […]