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:
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| Artist's reconstruction of D. stevensoni, D. nebrascensis, and D. cheyennese | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | †Ammonoidea |
| Order: | †Ammonitida |
| Suborder: | †Ancyloceratina |
| Family: | †Nostoceratidae (?) |
| Genus: | †Didymoceras Hyatt, 1894 |
| Species | |
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See text | |
| Synonyms | |
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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][2]
- 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
edit- ^ "Didymoceras Hyatt 1900". Paleobiology Database. Retrieved February 21, 2012.
- ^ Kennedy, W. J.; Landman, N. H.; Cobban, W. A.; Scott, G. R. (2000-04-01). "LATE CAMPANIAN (CRETACEOUS) HETEROMORPH AMMONITES FROM THE WESTERN INTERIOR OF THE UNITED STATES". Bulletin of the American Museum of Natural History. 2000 (251): 1–86. doi:10.1206/0003-0090(2000)251<0001:LCCHAF>2.0.CO;2. ISSN 0003-0090 – via BioOne.
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