Syringonautilidae is a family of

Nautiloidea 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 speciose, with over 2,500 recorded species. ...

from the middle to late

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

. Syringonautilidae comprise the last of the

Trigonoceratoidea The Trigonoceratoidea are a superfamily within the Nautilida that ranged from the Devonian to the Triassic, thought to have contained the source for the Nautilaceae in which ''Nautilus'' is found. Trigonoceratoidea are characterized by open-spi ...

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, Pseudonautilidae ...

which continued the

through the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

and into the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

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 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 ...

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. Th ...

; ''Clymenonautilus'', ''Juvavionautilus'', and ''Oxynautilus'' only from the Upper Triassic.Kummel, 1964, K439-440 '' Syringonautilus'',Kummel, 1964, K438 which has been found in the Alps, on

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

, 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 ; chg, ''Aqsaq Temür'', 'Timur the Lame') or as ''Sahib-i-Qiran'' ( 'Lord of the Auspicious Conjunction'), his epithet. ( chg, ''Temür'', 'Iron'; 9 April 133617–19 February 1405), later Timūr Gurkānī ( chg, ''Temür Kür ...

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'', 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 in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

.''Oxynautilus'' in the Payandé Formation
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

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