Syringonautilidae is a family of

Nautiloidea Nautiloids are a group of 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. Th ...

from the middle to late

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

. Syringonautilidae comprise the last of the Trigonoceratoidea and are the source for the

Nautilaceae The Nautilaceae form one of five superfamilies that make up the Nautilida according to Bernard Kummel (1964), and the only one that survived past the Triassic. The Nautilaceae comprise six families: Nautilidae, Paracenoceratidae, Pseudonautili ...

which continued the

through the

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

and into the

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

right down to the recent. Syringonautilidae is a strictly Triassic family, derived early in the Triassic from the Grypoceratidae.Kummel, 1964, K437-440

Diagnosis

The Syringonautilidae are characterized by generally involute shells - early whorls are in view - with broadly to sharply rounded whorl sections and smooth surfaces, except for growth lines and fine wire-like lirae in some forms. The

siphuncle The siphuncle is a strand of biological tissue, tissue passing longitudinally through the mollusc shell, shell of a cephalopod mollusc. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the li ...

is variable in position, and the suture is variably sinuous.Kummel, 1964, K437

Genera

Five genera are described in the Treatise, ''Syringonautilus'', ''Clymenonautilus'', ''Juvavionautilus'', ''Oxynautilus'', and ''Syringoceras''. ''Syringonautilus'' and ''Syringoceras'' are known from both the Middle and

Upper Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. T ...

; ''Clymenonautilus'', ''Juvavionautilus'', and ''Oxynautilus'' only from the Upper Triassic.Kummel, 1964, K439-440 ''

Syringonautilus Syringonautilidae is a family of Nautiloidea from the middle to late Triassic. Syringonautilidae comprise the last of the Trigonoceratoidea and are the source for the Nautilaceae which continued the Nautiloidea through the Mesozoic and into the ...

'',Kummel, 1964, K438 which has been found in the Alps, on

Spitsbergen Spitsbergen (; formerly known as West Spitsbergen; Norwegian language, Norwegian: ''Vest Spitsbergen'' or ''Vestspitsbergen'' , also sometimes spelled Spitzbergen) is the largest and the only permanently populated island of the Svalbard archipel ...

, in India and Japan has a rapidly expanding evolute shell with a perforate umbilicus and suboval whorl section. The suture has a faint ventral saddle and shallow lateral lobes. The siphuncle is subcentral. The surface is ornamented with fine lirae. ''Syringoceras'',Kummel, 1964, K440 found in Europe, on the island of

Timur Timur, also known as Tamerlane (1320s17/18 February 1405), was a Turco-Mongol conqueror who founded the Timurid Empire in and around modern-day Afghanistan, Iran, and Central Asia, becoming the first ruler of the Timurid dynasty. An undefeat ...

in Indonesia, and in western North America (Calif and Nev) is like ''Syringonautilus'' except that the siphuncle is near marginal. '' Clymenonautilus'',Kummel, 1964, K439 first of the strictly Upper Triassic genera, is evolute with a perforate umbilicus and deep dorsal impression when the whorl envelops a third of the previous. The whorl section is higher than wide with flattened flanks and rounded ventral and umbilical shoulders. The suture is transverse across the venter and has deep, tongue-like lobes on either side. The inner whorls are covered with fine lirae, and the outer ones are smooth. The position of the siphuncle is unknown. ''Clymenoceras'' comes from Europe. ''

Juvavionautilus Syringonautilidae is a family of Nautiloidea from the middle to late Triassic. Syringonautilidae comprise the last of the Trigonoceratoidea and are the source for the Nautilaceae which continued the Nautiloidea through the Mesozoic and into the ...

'', has a widely umbilicate, slowly expanding, evolute, perforate shell in which the flanks converge on a rounded to flattened venter so that the maximum width is just central of the umbilical shoulders. The suture includes a ventral saddle and broad lateral lobes. In some, there is a secondary ventral lobe. The siphuncle is subcentral. ''Juvavionautilus'' comes from Europe and Timur. '' Oxynautilus'', differs from the rest in that it has an involute, compressed lenticular shell with a narrow or acute (angular) venter which may or may not have a keel. The whorl section is much higher than wide with the maximum width slightly ventral of the umbilical shoulders. The suture is sinuous, including a narrowly rounded to angular ventral saddle and broad lateral lobes. The siphuncle is subcentral. ''Oxynautilus'' has been found in Europe in the Alps, in California in North America and in the Payandé Formation in Tolima,

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

.''Oxynautilus'' in the Payandé Formation
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org

Distribution

Fossils of ''Syringonautilidae'' have been found in Austria, China, Colombia, Hungary, Italy, the Russian Federation, and the United States (California, Nevada).''Syringonautilidae''
at

.org

References

Bibliography

* {{Taxonbar, from=Q7663359 Nautiloids Middle Triassic first appearances Late Triassic extinctions Molluscs of Asia Triassic animals of Asia Molluscs of Europe Triassic animals of Europe Molluscs of North America Triassic United States Molluscs of South America Triassic Colombia