Goniatite

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Goniatite
Temporal range: 390–251.4  Ma
Fossile J 2.jpg
A polished goniatite fossil
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Goniatitida
Hyatt, 1884
Suborders

Goniatids, informally goniatites, are ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago (around Eifelian stage). Goniatites (goniatitids) survived the Late Devonian extinction to flourish during the Carboniferous and Permian only to become extinct at the end of the Permian some 139 million years later.

Contents

Morphology

The prionoceratid Imitoceras rotatorium, showing characteristic goniatitic sutures. Early Carboniferous, Rockford Limestone, Rockford, Illinois. Imitoceras rotatorium (ammonite).jpg
The prionoceratid Imitoceras rotatorium , showing characteristic goniatitic sutures. Early Carboniferous, Rockford Limestone, Rockford, Illinois.

All goniatites possessed an external shell, which is divided internally into chambers filled with gas giving it buoyancy during the life of the animal. An open chamber at the front of the shell provided living space for the goniatitid animal, with access to open water through a ventral siphuncle. The general morphology and habit of goniatites was probably similar to that of their later relatives the ammonites, being free swimming and possessing a head with two well developed eyes and arms (or tentacles).

Goniatite shells are small to medium in size, almost always less than 15 centimeters (5.9 inches) in diameter and often smaller than 5 centimeters (2.0 inches) in diameter. The shell is always planispirally coiled, unlike those of Mesozoic ammonites in which some are trochoidal and even aberrant (called heteromorphs). Goniatitid shells vary in form from thinly discoidal to broadly globular and may be smooth or distinctly ornamented. Their shape suggests many were poor swimmers.

The thin walls between the internal chambers of the shell are called the septa, and as the goniatite grew it would move its body forward in the shell secreting septa behind it, thereby adding new chambers to the shell. The sutures (or suture lines) are visible as a series of narrow, wavy lines on the surface of the shell. The sutures appear where each septa contacts the wall of the outer shell.

The typical goniatitid has a suture with smooth saddles and lobes, which gives the name "goniatitic" to this particular suture pattern. In some the sutures have a distinctive "zigzag" pattern. Not all goniatitid ammonoides have goniatitic sutures. In some the sutures are ceratitic, in others, even ammonitic. Nor are goniatitic sutures limited to the Goniatidia. The sutures of nautiloids are by comparison somewhat simpler, being either straight or slightly curved, whereas later ammonoids showed suture patterns of increasing complexity. One explanation for this increasing extravagancy in suture pattern is that it leads to a higher strength of the shell.

Ecology

Ecologically, goniatites were limited to environments of normal-marine salinity—as appears to be the case for all cephalopods throughout their history. Goniatites are much more abundant and speciose in sediments that represent epicontinental seas than they are in those that represent the open ocean. Within these inland seas, goniatites' greatest abundance and diversity appears to have been achieved in deeper offshore and basinal environments rather than in nearshore environments. Known nearshore (e.g., lagoonal) occurrences have generally been ascribed to wash-in of shells from offshore waters.

Due to lack of strong evidence for any particular life mode (e.g., benthic nektonic, planktonic), it remains unclear what resources goniatites were capitalizing on in these offshore environments. Only a few goniatites' full trophic apparatuses have ever been described, and reports of stomach contents in these creatures' fossils remain questionable at best. However, goniatites clearly lacked the calcified jaw apparatuses developed in later ammonites; this has been cited as evidence against their having a durophagous (shell-crushing) diet.

Distribution

Goniatites are found in North America, Europe, North Africa and Australasia where they are used as index fossils in age determination and stratigraphic correlation. However, they seem to occur mostly in areas which at the time would have been tropical to subtropical. Almost any fossil-bearing limestone or shale from inland seas of the late Paleozoic tropics or subtropics is likely to yield some goniatites. [1] In the USA, such rocks are found from Maine, New York, and Virginia and in every state west to Nebraska and south to Texas and Alabama; as well as in parts of almost every western state (with the exception of North Dakota, Oregon, Washington, and Hawaii).

Notable goniatite occurrences are found in certain limestones in western part of Ireland (particularly Slieve Anierin) which are packed with beautifully preserved goniatite fossils. They are also found in marine bands of the Carboniferous coal measures in Europe and in marine rocks of the Pennsylvanian period in Arkansas. Large numbers of goniatites also occur in rocks from the Devonian period of Morocco. [2]

Related Research Articles

<span class="mw-page-title-main">Ammonoidea</span> Extinct subclass of cephalopod molluscs

Ammonoids are extinct spiral shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living coleoids than they are to shelled nautiloids. The earliest ammonoids appeared during the Devonian, with the last species vanishing during or soon after the Cretaceous–Paleogene extinction event. They are often called ammonites, which is most frequently used for members of the order Ammonitida, the only living group of ammonoids from the Jurassic up until their extinction.

<span class="mw-page-title-main">Nautilida</span> Order of cephalopods

The Nautilida constitute a large and diverse order of generally coiled nautiloid cephalopods that began in the mid Paleozoic and continues to the present with a single family, the Nautilidae which includes two genera, Nautilus and Allonautilus, with six species. All told, between 22 and 34 families and 165 to 184 genera have been recognised, making this the largest order of the subclass Nautiloidea.

<i>Goniatites</i> Extinct genus of molluscs

Goniatites is a genus of extinct cephalopods belonging to the family Goniatitidae, included in the superfamily Goniatitaceae. Hibernicoceras and Hypergoniatites are among related genera.

<span class="mw-page-title-main">Nautiloid</span> Extant subclass of cephalopods

Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living Nautilus and Allonautilus. Fossil nautiloids are diverse and species rich, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms (orthocones). No orthoconic and only a handful of coiled species, the nautiluses, survive to the present day.

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

Baculites is an extinct genus of heteromorph ammonite cephalopods with almost straight shells. The genus, which lived worldwide throughout most of the Late Cretaceous, and which briefly survived the K-Pg mass extinction event, was named by Lamarck in 1799.

Agathiceras is a subglobose goniatitid from the family Agathiceratidae, widespread and locally abundant in Lower Pennsylvanian to Middle Permian sediments, e.g. the Urals, Sicily, and Texas.

Aldanites is an extinct cephalopod genus belonging to the ammonoid order Goniatitida.

Dombarites is a genus belonging to the goniatitid family Agathiceratidae; extinct ammonoids which are shelled cephalopods more closely related to squid, octopus and other coleoids than to the superficially similar Nautilus

Beyrichoceras is a genus belonging to the goniatitid family Muensteroceratidae, a group of ammonoids, extinct shelled cephalopods related to belemnites and recent coleoids and more distantly to the nautiloids

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

Beyrichoceras is a genus belonging to the goniatitid family Maxigoniatitidae that lived during the Mississippian Period

Yinoceras is a genus of middle Permian goniatitid ammonite, the type genus for the subfamily Yinoceratinae of the family Pseudohaloritidae.

<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.

Prolobitidae is a family of middle and upper Devonian ammonoid cephalopods currently included in the goniatitid suborder Tornoceratina and superfamily Dimeroceratoidea, but previously included in the ancestral Anarcestida.

Aulatornoceratinae is one of three subfamilies of the goniatitid family Tornoceratidae, an extinct order of Paleozoic ammonoid cephalopods. Aulotornoceratinae was established as a subfamily by R.T.Becker, 1993, initially for Aulatornoceras, named by Schindewolf, 1922. Subsequently, four other genera have been added.

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

Cyclolobidae: Goniatitid Ammonoidea belonging to the Cycloloboidea with thickly discoidal to subglobular shells with a small but open umbilicus and ammonitic sutures with numerous lobes that have subparallel sides.

Agathiceratidae, as revised, makes up the goniatitid superfamily Agathiceratoidea. Agathiceratidae, which lived from the Upper Carboniferous (Pennsylvanian) to the Middle Permian, combine related genera with subdiscoidal to globular shells that have a small umbilicus and goniatitic sutures and are prominently longitudinally lirate. The explanation for the Agathiceratidae is that for the Agathiceratoidea.

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

Prolecanitida is an order of extinct ammonoid cephalopods, the major Late Paleozoic group of ammonoids alongside the order Goniatitida. Prolecanitids had narrow shells, discoidal (disc-shaped) to thinly lenticular (lens-shaped). They retained a retrochoanitic siphuncle, a simple form with septal necks extending backwards. As is typical for ammonoids, the siphuncle sits along the ventral margin of the shell.

<span class="mw-page-title-main">Prolecanitoidea</span> Extinct superfamily of ammonites

Prolecanitoidea is a taxonomic superfamily of ammonoids in the order Prolecanitida. Prolecanitoidea is one of two superfamilies in the order, along with the younger and more complex Medlicottioidea. The Prolecanitoidea were a low-diversity and morphologically conservative group. They lived from the Lower Carboniferous up to the Middle Permian. Their shells are generally smooth and discoidal, with a rounded lower edge, a moderate to large umbilicus, and goniatitic to ceratitic sutures. Suture complexity varies from 10 up to 22 total lobes ; new lobes are added from subdivision of saddles adjacent to the original main umbilical lobe.

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

Agoniatitida, also known as the Anarcestida, is the ancestral order within the cephalopod subclass Ammonoidea originating from bactritoid nautiloids, that lived in what would become Africa, Asia, Australia, Europe, and North America during the Devonian from about the lower boundary of Zlichovian stage into Taghanic event during upper middle Givetian, existing for approximately 25 million years.

The Uddenitinae a subfamily of the Medlicottiidae, a family of ammonoid cephalopods included in the Prolecanitida. The Uddenitinae, proposed by Miller and Furnish, and known from the Pennsylvanian and Lower Permian, are transitional between the ancestral Pronoritidae and the more traditional medlicottiids.

References

  1. "ammonoid | fossil cephalopod". Encyclopedia Britannica. Retrieved 2017-11-14.
  2. "Devonian Period | geochronology". Encyclopedia Britannica. Retrieved 2017-11-14.