''Hipparionoceras'' is a genus of
oncocerids from the middle Devonian of Europe, North America, and China that lived around 395 million years ago.
The shell of ''Hipparionoceras'' is curved, rapidly expanding, flared toward the aperture. The curvature is endogastric with the ventral side somewhat concave in profile.
The siphuncle is subventral, empty, with segments expanded into the short but broad chambers. Septa are close spaced, their curvature shallow.
''
Polyelasmoceras'' and ''
Macrodomoceras'' are related genera, also from the Middle Devonian. ''
Cadoceras'' from the Middle
Silurian
The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...
may be ancestral.
References
* Walter C. Sweet, 1964. Nautiloidea-Oncocerida. Treatise on Invertebrate Paleontilogy, Part K. Geological Society of America.
Hipparionocerasin Fossilworks Gateway
Prehistoric nautiloid genera
Oncocerida
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