''Arctocephalites'' is an extinct
ammonitic cephalopod genus from the
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
with a wide northern distribution belonging to the stephanoceratacean family, Cardioceratidae.
[Arkell et at, 1957, Mesozoic Ammonoidea , Treatise on Invertebrate Paleontology, Part L, Mollusca 4, R.C. Moore, ed. p.L301]
The inner whorls of the ''Arctocephalites'' shell are sharply ribbed but change abruptly to smooth. The such, as characteristic of the family, is complex with large first lateral lobe and well-developed umbilical lobe.
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''Arctocephalites'' has been found in Bathonian age sediments at Cook Inlet, Alaska, in western Montana, and in the North Sea at paleolatitudes ranging from about 30deg N to 50deg N. It has been found in equivalent age sediments in the Volga and Pechora river basin in Russia Correlation of Upper Bajocian-Bathonian Zones in Siberia]
..S.V. Meledina et al 2009 as well as in Greenland, FanzJoseph Land, NovayZemlya, and eastern Siberia.
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''References''
Jurassic ammonites of North America
Bathonian life
{{Ammonite-stub