Didymoceras

Didymoceras is an extinct genus of ammonite cephalopod from the Late Cretaceous epoch (approximately 76 Ma). It is one of the most bizarrely shaped genera, with a shell that spirals upwards into a loose, hooked tip. It is thought to have drifted in the water vertically, moving up and down. The generic name is Greek for "paired horns".

Didymoceras
Temporal range:
Artist's reconstruction of D. stevensoni, D. nebrascensis, and D. cheyennese
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: †Ammonoidea
Order: †Ammonitida
Suborder: †Ancyloceratina
Family: †Nostoceratidae (?)
Genus: †Didymoceras
Hyatt, 1894
Species

See text

Synonyms
  • Cirroceras Conrad, 1866
  • Helicoceras d'Orbigny, 1842
  • Helicoceras Whitfield, 1877
  • Emperoceras Hyatt, 1894
  • Didymoceratoides Kennedy & Cobban, 1993

Its taxonomic place is often in flux, being placed in either Turrilitidae, Nostoceratidae, or its own family, Didymoceratidae. Species included in the genus are the following:[1]

D. stevensoni shell exhibit in the Houston Museum of Natural Science
  • Didymoceras angulatum (Meek and Hayden, 1860)
  • Didymoceras binodosum Kennedy and Cobban, 1993
  • Didymoceras californicum Anderson, 1958
  • Didymoceras cheyenense (Meek and Hayden, 1856)
  • Didymoceras cheyennense (Meek and Hayden, 1856)
  • Didymoceras cochleatus (Meek and Hayden, 1858)
  • Didymoceras hidakense Shigeta in Shigeta et al., 2016
  • Didymoceras hornbyense (Whiteaves, 1876)
  • Didymoceras navarroensis (Shumard, 1861)
  • Didymoceras nebrascense Meek and Hayden, 1856)
  • Didymoceras newtoni (Whitfield, 1877)
  • Didymoceras nicolletii (Hall and Meek, 1856)
  • Didymoceras platycostatum Kennedy and Cobban, 1993
  • Didymoceras stevensoni (Whitfield, 1877)
  • Didymoceras subtuberculatum Howarth, 1965
  • Didymoceras tenuicostatus (Meek and Hayden, 1858)
  • Didymoceras tortus (Meek and Hayden, 1858)
  • Didymoceras tricostatus (Whitfield, 1897)
  • Didymoceras umbilicatu (Meek and Hayden, 1858)
  • Didymoceras uncus (Meek and Hayden, 1858)
  • Didymoceras vespertinus (Conrad, 1874)

References
  1. "Didymoceras Hyatt 1900". Paleobiology Database. Retrieved February 21, 2012.
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