Asteroceras obtusum

Asteroceras obtusum, the obtuse star ammonite, is an extinct species of cephalopod belonging to the ammonite subclass and to the family Arietitidae. These fast-moving nektonic carnivores lived during the lower Jurassic period, upper Sinemurian, around 189-196 million years ago.

Asteroceras obtusum
Temporal range: Sinemurian [1]
Fossil of Asteroceras obtusum from Lyme Regis, on display at Museo di Scienze Naturali Enrico Caffi, Bergamo
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: †Ammonoidea
Order: †Ammonitida
Family: †Arietitidae
Genus: †Asteroceras
Species:
†A. obtusum
Binomial name
†Asteroceras obtusum
Sowerby, 1817

Description

Asteroceras obtusum has a shell reaching a diameter of about 8–20 centimetres (3.1–7.9 in).[2]

Distribution

Fossils of this species may be found in Mexico, Russia, France, Germany (Aalen) and United Kingdom, at Lyme Regis in the Asteroceras obtusum zone of Upper Sinemurian age[3][4][5][6][7]

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References
  1. Sepkoski, Jack Sepkoski's Online Genus Database
  2. Ammonites
  3. Martell, D. M. 1995. An Ichthyosaur with Preserved Soft Tissue from the Sinemurian of Southern England. Palaeontology. 38(4): 897-903
  4. Paleobiology Databases
  5. Biolib
  6. Mikhail Semenovich Mesezhnikov, Gerd Ernst Gerold Westermann The Jurassic Ammonite Zones of the Soviet Union, Edizione 223
  7. Claudio Bartolini, James Lee Wilson, Timothy Frost Lawton Mesozoic Sedimentary and Tectonic History of North-central Mexico, Edizione 340


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