''Polyptychoceras'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

s from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, and

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. It was first named by Hisakatsu Yabe in 1927.Tatsuro Matsumoto and Mitsutoshi Nihongi (1979
An Interesting Mode of Occurrence of Polyptychoceras
Japan Academy

Species and subspecies

This genus contains the following eight species and one

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

, ''Subtychoceras'', which contains one

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. * ''Polyptychoceras mihoense'' * ''Polyptychoceras pseudogaultinum'', could reach a length of 100 – 120 mm * ''Polyptychoceras haradanum'' (Yokoyama) * ''Polyptychoceras obatai'' * ''Polyptychoceras obliquecostatum'' * ''Polyptychoceras subunduratum'' * ''Polyptychoceras obstrictum'' (Jimbo) * ''Polyptychoceras vancouverensis'', located around the Trent and Puntledge Rivers. Due to its shape, fossil poachers often call it the "paperclip ammonite" or "candy cane". * ''Polyptychoceras (Subptychoceras) yubarense'', could reach a maximum length of 200 mm

Description

Diplomoceratidae - Polyptychoceras species

''Polyptychoceras'' is a

heteromorph The Ancyloceratina were a diverse suborder of ammonite most closely related to the ammonites of order Lytoceratina. They evolved during the Late Jurassic but were not very common until the Cretaceous period, when they rapidly diversified and bec ...

ammonite, meaning that its shell does not curl up into the tight spiral shape which shells of ammonites from the subclass

Ammonoidea Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttle ...

typically do. ''Polyptychoceras'' shells have an abrupt weight increase after formation of the initial shaft, which represents the shell's automatic balance condition. This would have caused the shell to topple over if on land. The soft body of the animal would have to have been large, in order to keep the falling shaft off of the ground. The body would not have been resistant to the pressing shell. Although the shafts in the fossils of the shells are usually parallel to each other, small aberrations during each growth stage often caused abrupt constrictions in the shape of the shell.''Ammonoid Paleobiology'' (Topics in Geobiology) by Neil H. Landman, Kazushige Tanabe, and Richard Arnold Davis; page 224. Published 1996

Springer Springer or springers may refer to: Publishers * Springer Science+Business Media, aka Springer International Publishing, a worldwide publishing group founded in 1842 in Germany formerly known as Springer-Verlag. ** Springer Nature, a multinationa ...

. Retrieved on 2008-05-02

Life

A Japanese study in 1979 suggested that ''Polyptychoceras'' lived and travelled in schools, similarly to modern

cuttlefish Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of ...

. Individual fossil specimens of a particular species of ''Polyptychoceras'' are frequently found in sediments laid down in the same bed of water, around the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The ...

and Upper

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...

faunal stage In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by conventi ...

s of the

Epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

. ''Polyptychoceras'' was probably

buoyant Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pr ...

, and swam in a slow, somewhat up-and-down locomotion. It also likely preferred living in sheltered parts of deep sea levels, although how deep is uncertain. ''Subptychoceras yubarense'' was likely very long like an eel, and preferred a

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

mode of life.

Distribution

Fossils of ''Polyptychoceras'' have been found in Angola, Antarctica, Argentina, Austria, Japan, Mexico, the Russian Federation, and the United States (California).''Polyptychoceras''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

References

External links