Michelinoceras

Michelinoceras is an extinct genus of straight-shelled cephalopods in the family Michelinoceratidae, order Orthocerida, subclass Nautiloidea. It is known from fossil records of the Paleozoic era and is represented in marine sedimentary rocks from multiple regions, indicating a broad geographic distribution in ancient oceans.

Morphology and anatomy of Michelinoceras fossils show a long, slender orthoconic shell with a relatively circular cross-section. The internal chambers (camerae) are separated by septa, and the siphuncle—a tube connecting the chambers for buoyancy regulation—appears in a position that can range from subcentral to near the ventral margin, depending on the species. Surface ornamentation is typically modest, with some variability among species.

Ecology and life habits: As with other orthocerids, Michelinoceras was likely nektonic and carnivorous, inhabiting marine environments where it could use buoyancy control to maneuver through the water column and pursue small invertebrate prey.

Temporal range and distribution: Fossils attributed to Michelinoceras are dated to the Paleozoic era, with records spanning portions of the Ordovician to Devonian periods. Geographic occurrences include North America and Europe, reflecting a widespread presence in Paleozoic seas.

Taxonomic context: Michelinoceras is a member of Michelinoceratidae, a family of long-shelled orthocerids that contribute to the understanding of cephalopod evolution and Paleozoic biostratigraphy.