Didymoceras nebrascense

Didymoceras nebrascense; Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	†Ammonoidea
Order:	†Ammonitida
Suborder:	†Ancyloceratina
Family:	†Nostoceratidae (?)
Genus:	†Didymoceras
Species:	†D. nebrascense
Binomial name
	†Didymoceras nebrascense; (Meek and Hayden, 1856)
Synonyms
	Ancyloceras nebrascensis Meek and Hayden, 1856; Cirroceras nebraskense (Meek and Hayden, 1856); Didymoceras nebrascensis (Meek and Hayden, 1856); Emperoceras beecheri Hyatt, 1894, ; Emperoceras simplicostatum Whitfield, 1902; Helicoceras nebrascense (Meek and Hayden, 1856); Heteroceras nebrascense (Meek and Hayden, 1856); Heteroceras simplicostatum Whitfield, 1902; Nostoceras (Didymoceras) nebrascense (Meek and Hayden, 1856); Turrilites nebrascensis (Meek and Hayden, 1856);

Didymoceras nebrascense was an extinct species of heteromorph ammonite from the upper Campanian age (around 83 to 70 million years ago). It was sexually dimorphic, with two adult sizes averaging at 270 mm (11 in) and 180 mm (7.1 in) high for females and males respectively. It exhibited three distinct growth stages. The first growth stage was composed of one or two straight sharply bending sections and a gently curved third. The second growth stage is composed of around three and a half loosely coiling whorls. The last (adult) growth stage is composed of a U-shaped bend facing upwards.