''Holconautilus'' is a genus of

nautiloid 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 ...

s from the family

Tainoceratidae Tainoceratidae is a family of late Paleozoic and Triassic nautiloids that are a part of the order Nautilida, characterized by large, generally evolute shells with quadrate to rectangular whorl sections. Shells may bear ribs or nodes, or both. ...

and order

Nautilida 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 ''Allonauti ...

, named by Mojsisovics, 1902, and known from Upper

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 ...

sediments in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and E Indies (

Timor Timor (, , ) is an island at the southern end of Maritime Southeast Asia, in the north of the Timor Sea. The island is Indonesia–Timor-Leste border, divided between the sovereign states of Timor-Leste in the eastern part and Indonesia in the ...

). Its shell, evolute, discoidal, with simple coarse lateral ribbing; whorl section, subrectagular with a broadly arched venter. ''Holconautilus'' somewhat resembles the Permo-Triassic '' Pleuronautilus'' except its suture has ventral saddles instead of ventral lobes and lateral ribs are continuous. '' Anoploceras'', from the same time and place as ''Holconautilus'' is also similar except for having a wider whorl section and a venter that is slightly concave.

References

* Bernhard Kummel, 1964. Nautiloidea-Nautilida.

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part K. Geological Soc. of America and University of Kansas press. Teichert and Moore (eds) Prehistoric nautiloid genera Nautiloids {{paleo-Nautiloidea-stub