''Titanoceras'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus in the

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 ...

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 ...

from the Pennsylvanian and Lower

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

of North America and Western Australia. ''Titanoceras'' grew to be fairly large, with a tightly spiraled shell that reached a diameter of about 8 in (20 cm +) with about three volutions. The inner coils are partially enveloped by the next outer, resulting in a channel or impression along the inner rim, the dorsum. Otherwise all whorls are visible. (The descriptive term is

evolute In the differential geometry of curves, the evolute of a curve is the locus (mathematics), locus of all its Center of curvature, centers of curvature. That is to say that when the center of curvature of each point on a curve is drawn, the result ...

). Whorls have a somewhat rectangular cross section that is wider than high; in contrast with the otherwise similar and contemporary '' Domatoceras''. The venter, which forms the outer rim, may be broadly arched.

Septa SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

are close spaced making chambers broad but short. Sutures have shallow lobes along the sides and across the venter and short saddles in between, along the ventro-lateral shoulders, but go straight across the dorsum. ''Titanoceras'' is found is

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

, indicating it lived in shallow-water carbonate banks. It could no doubt swim, but probably was not an active

swimmer Swimming is an individual or team racing sport that requires the use of one's entire body to move through water. The sport takes place in pools or open water (e.g., in a sea or lake). Competitive swimming is one of the most popular Olympic ...

unlike fish and squid. It most likely spent its time crawling over or just above the sea floor. ''Titanoceras'' probably preyed upon crustaceans, bottom fish, and perhaps other cephalopods. ''Titanoceras'' is placed in the Grypoceratidae, a family of similar genera within the Nautilida. Nautilid families that are more similar and have a common ancestor are combined in superfamilies. The Grypoceratidae are part of the Trigonocerataceae.

References

* Kümmel, B. 1964; Nautiloidea - Nautilida, in the

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 Nautiloidea; Geological Society of America and University of Kansas press. * Miller, A.K and Unklesbay, A.G 1942; Permian Nautiloids from Western United States; Journal of Paleontology, V.16, no 6, pp 719–238, Nov 1942. * Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. ''Bulletins of American Paleontology'' 363: 1–560

{{Taxonbar, from=Q7809864 Nautiloids Pennsylvanian first appearances Permian genus extinctions Paleozoic life of Yukon