Alocolytoceras Temporal range: | |
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Scientific classification | |
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.
Kammerkaroceras is an extinct cephalopod genus from the Lower Jurassic belonging to the ammonoid family Psiloceratidae.
Alsatites is an extinct genus of cephalopod belonging to the Ammonite subclass. They lived during the Hettangian and are generally extremely evolute, many whorled. Keel broad and blunt organisms, they also exhibit a primary ribbing which is close and persistent.
Asapholytoceras is a lytoceratid ammonite, originally from the upper Lower Jurassic of southeastern Europe with high, compressed whorls and a sharp angle to the umbilical shoulder. The exposed suture has four primary lobes on either side; the internal dorsal lobe is not cruciform.
Aspidoceras is an extinct ammonoid cephalopod genus belonging to the family Aspidoceratidae.
Arnioceras is an extinct genus of large, evolute, discoidal ammonite from the Lower Jurassic. The shell is normally coiled so that all whorls are exposed. Sides bear strong sharp ribs that are straight until reaching the ventrolateral edge where they swing forward and fade. The rim (venter) is keeled and free of grooves.
Dobrogeites is a genus of ammonoids from the order Ceratitida, included in the family Megaphyllitidae that produced evolute compressed planispiral shells with rounded venters, inner whorls ornamented as in Tirolites, outer whorls smooth, suture with multiple smooth lobes; Initially found in Anisian sediments in Romania.
Euaptetoceras is an evolute hildoceratoid ammonite from the lower Middle Jurassic, included in the family Hammatoceratidae and the subfamility Hammatoceratinae. The genus may be a junior synonym for Eudmetoceras of Buckman, 1920.
Labyrinthoceras is an extinct cephalopod genus included in the ammonoid family Sphaeroceratidae, a member of the superfamily Stephanoceratoidea, that lived during middle of the Jurassic Period.
Macrocephalites is a genus of the stephanoceratoid ammonite family Macrocephalitidae, diagnostic of the Callovian stage of the Middle Jurassic. Three subgenera, Dolikephalites, Kamptokephalites, and Pleurocephalites are recognized in addition to Macrocephalites itself, with Indocephalites tentatively included as the fourth.
Kepplerites is a moderately evolute ammonite from the lower Callovian included in the Stephanoceratoidea.
Blanfordiceras is a strongly ribbed, evolute ammonite included in the perisphinctacean family, Neocomitidae that lived during the latest Jurassic. The shell of Blanfordiceras is discoidal, with evolute coiling and all whorls visible so as to have a broad umbilicus. Exposed whorls are ornamented with strong ribbing that arises from the umbilicus, bifurcating on the outer flanks and extending onto the venter. In general form Blanfordiceras is similar to Berriasella, although with a more rounded whorl section.
Craspedites is an ammonoid cephalopod included in the Perisphinctoidea that lived during the Late Jurassic and Early Cretaceous, found in Canada, Greenland, Poland, and the Russian Federation.
Lytoceratidae is a taxonomic family of ammonoid cephalopods belonging to the suborder Lytoceratina, characterized by very evolute shells that generally enlarge rapidly, having whorls in contact but mostly overlapping very sightly, or not at all.
Megalytoceras is an extinct genus of ammonite from the middle Jurassic, belonging to the suborder Lytoceratina.
Grammoceras is an extinct genus of ammonite found in Yorks Ravenscar, England, from Jurassic period sediments. Its overall distribution is fairly worldwide.
Pleuroacanthites is one of two genera included in the Early Jurassic Pleuroacanthitidae and sole representative of the subfamily Pleuroacanthitinae. The shell of Pleuroacanthites is very evolute, with numerous whorls subcircular in section becoming incipiently keeled in the adult. Early whorls have parabolic nodes, later whorls are covered with oblique line which form a long ventral sinus. Sutures have lytoceratid (moss-like) lobes but more or less phylloid saddle endings.
Megalytoceratinae is a subfamily of lytoceratids ammonites consisting of planulate forms, i.e. those with moderately evolute compressed shells with bluntly rounded venters, in which the outer whorls become smooth and sutures tend to resemble those of the Perisphinctidae. The family includes three genera, Megalytoceras, and Metrolytoceras, from the Middle Bajocian of England, Perilytoceras from the Toarcian and a fourth possible member, Asapholytoceras, from the Toacian of southeastern Europe.
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.