Gymnitidae

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Gymnitidae
Temporal range: Early Triassic–Middle Triassic
Gymnitidae - Gymnites incultus-001.JPG
Gymnites incultus from Bosnia, on display at Galerie de paléontologie et d'anatomie comparée in Paris
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ceratitida
Superfamily: Pinacoceratoidea
Family: Gymnitidae
Waagen, 1898
Genera

See text

Gymnitidae is a family of Lower to Middle Triassic ammonite cephalopods with evolute, discoidal shells.

Hyatt and Smith (1905, p. 114-115) included the Gymnitidae in the suborder Ceratitoidea, which later became the superfamily Ceratitaceae and included in it genera more primitive than Gymnites as well as the more advanced Gymnites. Those being Xenaspis , Flemingites , and Ophiceras . Derivation as shown in Smith (1932 p. 30) is from Xenodiscus .

The more primitive Xenaspis, Flemingites, and Ophiceras, found in Lower Triassic beds in western America have ceratitic sutures. The more developed Gymnites has deeply digitate ammonitic sutures.

Arkell, et al., 1957, in the Treatise on Invertebrate Paleontology, on the other hand included the Gymnitidae in the Pinacocerataceae as the earlier and more primitive of its two families, combining Gymnites with coeval and more advanced forms. Genera included in the Gymnitidae sensu Arkell include Eogymnites , Buddhaites , Japanites , and of course, Gemnites. The genus Xiphogymnites was included by Tozer in 1981.

Whether to place the Gymnitidae in the Ceratitaceae, as in Hyatt and Smith, combining Gymnites with its more primitive relatives, or in the Pinacocerataceae, as in Arkell et al., combining Gymnites with its coeval or more advanced relatives is a matter of perspective which does little to change the overall phylogeny.

Related Research Articles

Xiphogymnites is an extinct ammonoid cephalopod genus from the Triassic included in the family Gymnitidae. It is known from the Balkans in eastern Europe.

Arctogymnites is a genus of ammonoid cephalopods from the middle Triassic included in the ceratitid subfamily Beyrichitinae. Related genera include Beyrichites, Frechites, Gymnotoceras, and Salterites

Badiotites is a genus of extinct ammonoid cephalopods belonging to the ceratitid family Badiotitidae. It was previously included with Lecanites in the Lecanitidae, a family formerly of the Clydonitaceae but reassigned by Tozer (1981) to the Danubitaceae. The Badiotitidae is included in the Ceratitaceae.

Ussuria is a genus of Lower Triassic ammonites with a smooth, involute discoidal shell with submonophyllic sutures, belonging to the ceratitid family Ussuriidae.

<span class="mw-page-title-main">Ceratitida</span> Extinct order of molluscs

Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post-Triassic ammonites.

<span class="mw-page-title-main">Acanthoceratidae</span> Family of molluscs (fossil)

Acanthoceratidae is an extinct family of acanthoceratoid cephalopods in the order Ammonitida, known from the Upper Cretaceous. The type genus is Acanthoceras.

Adrianitidae is a family in the Adrianitaceae, a superfamily of ammonites in the cephalopod order, Goniatitida, known from the Middle Pennsylvanian to the Middle Permian.

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

Medlicottiidae is a family of ammonoid cephalopods belonging to the Prolecanitida, known from the Upper Carboniferous (Pennsylvanian) to the Early Triassic.

The Ophiceratidae is a family in the ammonoid order Ceratitida from the Lower Triassic, previously included in the Otocerataceae but now placed in the Noritiaceae as revised.

Clydonitoidea, formerly Clydonitaceae, is a superfamily in the ammonoid cephalopod order Ceratitida characterized by generally costate and tuberculate shells with smooth, grooved, or keeled venters and sutures that are commonly ceratitic or ammonitic but goniatitic in a few offshoots.

Ceratitoidea, formerly Ceratitaceae, is an ammonite superfamily in order Ceratitida characterized in general by highly ornamented or tuberculate shells with ceratitic sutures that may become goniatitic or ammonitic in some offshoots.

<span class="mw-page-title-main">Eoderoceratidae</span> Extinct family of ammonites

Eoderoceratidae is the ancestral and most primitive family of the Eoderoceratoidea; lower Jurassic ammonite cephalopods, characterized by evolute, commonly serpenticonic, shells that had long body chambers and would have had no stable floating position; and thus resemble contemporary Psiloceratoidea. Spines, or tubercles, are typically found in two rows on the inner and outer parts of the whorl sides, joined by radial ribs. These are often more developed on the inner and middle whorls, becoming less so or absent on the outer. Sutures are highly complex.

<i>Gymnites</i>

Gymnites is a genus of ammonoid cephalopod from the Middle Triassic belonging to the ceratitid family Gymnitidae. These nektonic carnivores lived during the Triassic period, Anisian age.

Aplococeratidae is a family of ceratitids from the Middle Triassic with very simplified sutures and a tendency to lose their ornamentation. Shells are generally evolute, more or less compressed, with rounded venters. Ornamentation if present consists of umbilical ribs that disappear outwardly, toward the venter. The suture is ceratitic or goniatitic.

Inyoites is an ammonoid genus from the Lower Triassic, included in the ceratitid family Inyoitidae.

Dieneria is a genus of ceratitid ammonoid cephalopods from the Late Triassic of western North America with a smooth discoidal shall of which the venter is truncate and the suture simple. Only the first lateral lobe is slightly serrated, the other lobes entire (smooth)

Olenekoceras is an ammonoid cephalopod from the Lower Triassic included in the ceratitid family Sibiritidae, once included in the Noritaceae but now in the Ceratitaceae.

<i>Ophiceras</i> Genus of molluscs (fossil)

Ophiceras is a genus of smooth, evolute ceratitid ammonites from the Early Triassic, with a rounded venter. Fossils of the genus have been found in Armenia, Azerbaijan, China, Greenland, and India.

<i>Meekoceras</i> Extinct genus of ceratitid ammonites

Meekoceras is a genus of ceratitid ammonites with a discoidal shell that lived during the Early Triassic Epoch.

Eophyllites is a genus of ammonoid cephalopods from the Lower Triassic and a predecessor of genera like Monophyllites and Ussurites.

References