Pseudohaloritidae
Encyclopedia
Pseudohaloritidae is the larger of two families that form the goniatitid superfamily Pseudohaloritaceae
, the other being the monogenerc Maximitidae
. They are part of the vast array of shelled cephalopods known as ammonoids that are more closely related to squid
s, belemnites, octopus
es, and cuttlefish
, than to the superficially similar Nautilus
.
The Pseudohaloritide which now contains some 14 genera in three subfamilies is characterized by small, subdiscoidal to subglobular, involute shells, the surface of which may be smooth or with coarse longitudinal lirae and/or transverse ribs. The siphuncle
is retrosiphonitic, a hold-over character from the nautiloids, usually subcentral or situated within dorsal septal flexure but ventral-marginal in first and second whorls. Sutures have four pairs of lobes, the ventral one being rounded and spatulate, the interior three clustered and narrow. External lobes are either smooth are variably serrate.
The Pseudohaloritidae was established by Miller and Furnish (1957) for three related genera with similar sutures and aberrant siphuncles that are removed from the ventral margin. One, Maximites, has been put in a family of its own, the Maximitidae. The other two, Neoaganides and Pseudohalorites are retained in the Pseudohaloritidae, to which has been added about a dozen more genera, mostly from China..
Maximites differs in having a bifid ventral lobe and a siphuncle that is ventral, but not marginal. It is also older, as early as the Middle Pennsylvanian
(m U Carb) rather than from the Upper Pennsylvanian (uU Carb) when pseudohaloritids, as emended, make their first appearance.. Maximites is thought to have given rise to the Neoaganides and thus to the Pseudohaloritidae, and in turn may have be derived from Imitoceras. On the other hand the suture indicates that Neoaganides may have developed directly from Imitoceras. The ventral lobe of Neoaganides is like that of Imitoceras, smooth and rounded, but the lateral lobes differ from those of both Imitoceras and Maximites in being pointed.
The aberrant position of the siphuncle well away from the ventral margin and in some near the dorsum is characteristic of, although not unique to, this family. However no link is indicated between these Pennsylvanian and Permian
forms and the Upper Devonian
Clymeniids
with their well established dorso-marginal siphuncles.
Pseudohaloritaceae
Pseudohaloritaceae is one of four superfamilies of the Tornoceratatina suborder, a member of the Goniatitida order. They are an extinct group of ammonoid, which are shelled cephalopods related to squids, belemnites, octopuses, and cuttlefish, and more distantly to the nautiloids.-References:* ...
, the other being the monogenerc Maximitidae
Maximitidae
Maximitidae is one of two families of the Pseudohaloritaceae Superfamily, a member of the Goniatitida order. They are an extinct group of ammonoid, which are shelled cephalopods related to squids, belemnites, octopuses, and cuttlefish, and more distantly to the nautiloids.-References:* accessed on...
. They are part of the vast array of shelled cephalopods known as ammonoids that are more closely related to squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
s, belemnites, octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
es, and cuttlefish
Cuttlefish
Cuttlefish are marine animals of the order Sepiida. They belong to the class Cephalopoda . Despite their name, cuttlefish are not fish but molluscs....
, than to the superficially similar Nautilus
Nautilus
Nautilus is the common name of marine creatures of cephalopod family Nautilidae, the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in two genera, the type of which is the genus Nautilus...
.
The Pseudohaloritide which now contains some 14 genera in three subfamilies is characterized by small, subdiscoidal to subglobular, involute shells, the surface of which may be smooth or with coarse longitudinal lirae and/or transverse ribs. The siphuncle
Siphuncle
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and Spirula...
is retrosiphonitic, a hold-over character from the nautiloids, usually subcentral or situated within dorsal septal flexure but ventral-marginal in first and second whorls. Sutures have four pairs of lobes, the ventral one being rounded and spatulate, the interior three clustered and narrow. External lobes are either smooth are variably serrate.
The Pseudohaloritidae was established by Miller and Furnish (1957) for three related genera with similar sutures and aberrant siphuncles that are removed from the ventral margin. One, Maximites, has been put in a family of its own, the Maximitidae. The other two, Neoaganides and Pseudohalorites are retained in the Pseudohaloritidae, to which has been added about a dozen more genera, mostly from China..
Maximites differs in having a bifid ventral lobe and a siphuncle that is ventral, but not marginal. It is also older, as early as the Middle Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
(m U Carb) rather than from the Upper Pennsylvanian (uU Carb) when pseudohaloritids, as emended, make their first appearance.. Maximites is thought to have given rise to the Neoaganides and thus to the Pseudohaloritidae, and in turn may have be derived from Imitoceras. On the other hand the suture indicates that Neoaganides may have developed directly from Imitoceras. The ventral lobe of Neoaganides is like that of Imitoceras, smooth and rounded, but the lateral lobes differ from those of both Imitoceras and Maximites in being pointed.
The aberrant position of the siphuncle well away from the ventral margin and in some near the dorsum is characteristic of, although not unique to, this family. However no link is indicated between these Pennsylvanian and Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
forms and the Upper Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
Clymeniids
Clymeniida
The Clymeniida constitute a unique order of ammonoid cephalods from the Upper Devonian characterized by having an unusual dorsal siphuncle. They measured about 4 cm in diameter and are restricted to Europe, North Africa, and possibly Australia....
with their well established dorso-marginal siphuncles.