Nannolytoceras Temporal range:
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Fossil shells of Nannolytoceras tripartitum from Alpes-de-Haute-Provence, on display at Galerie de paléontologie et d'anatomie comparée in Paris | |
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Genus: | Nannolytoceras Buckman, 1905
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Nannolytoceras is an extinct genus of lytoceratid ammonite, family Lytoceratidae, with a stratigraphic range extending from the Bajocian age to Bathonian age (Medium Jurassic). [1]
Shells of Nannolytoceras species reach a diameter of about 46–75 millimetres (1.8–3.0 in). [2] [3] The shell is evolute, smooth, tubular to compressed, with a variable number of more or less regularly spaced deep constrictions. [3] The very thin ribs crossing the ventral region are barely visible. Umbilicus is relatively large. The suture line is of ammonitic type. [4] These cephalopods were fast-moving nektonic carnivores. [5]
Fossils of species within this genus have been found in the Jurassic rocks of Italy, Spain, [5] Slovakia, [6] and France. [7]