Alocolytoceras

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Alocolytoceras
Temporal range: Toarcian [1]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Family: Lytoceratidae
Subfamily: Alocolytoceratinae
Genus: Alocolytoceras
Hyatt, 1900 [2]

Alocolytoceras is a lytoceratid ammonite with whorls that pass during growth from round to oval, rounded-quadrate, or compressed; with about 19 deep constrictions per whorl, with as many as 21 sharp ribs in between. The shell is evolute. All whorls are visible from either side.

Alocolytoceras belongs to the lytoceratid subfamily Alocolytoceratinae, which also includes Pachylytoceras and Pleurolytoceras . It is known from the upper Lower Jurassic of Europe and the Himalaya.

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<span class="mw-page-title-main">Lytoceratidae</span> Extinct family of molluscs

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Alocolytoceratinae is a subfamily of lytoceratids that comprises genera characterized by many deep constrictions in the shell resulting in capricorn-like ornamention, especially in the middle whorls, but becoming smooth and more involute in the outer whorls. Saddle endings in the suture tend to be phylloid, (leaf-like).

Hemilytoceras is a lytoceratin ammonite genus with round inner whorls, outer whorls becoming depressed and in some developing high lamellae (ribs) that bend forward over the venter. The type species H. immanae came from the Tithonian of Europe. The genus is known from the overall Upper Jurassic of central and southern Europe, North Africa, and western India.

Ochetoceras is a genus of ammonites, belonging to the Oppeliidae, that lived during the Late Jurassic from the early Oxfordian to the early Tithonian, and type for the subfamily Ochetoceratinae.

References

Notes
  1. Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Cephalopoda entry)". Bulletins of American Paleontology. 363: 1–560. Archived from the original on 2016-02-25. Retrieved 2017-10-18.
  2. "Paleobiology Database - Alocolytoceras" . Retrieved 2017-10-19.
Bibliography