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Murrayoceras

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Genus of nautiloids

Murrayoceras
Temporal range: M Ordovician
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Nautiloidea
Order: Orthocerida
Family: Baltoceratidae
Genus: Murrayoceras
Foeste, 1926

Murrayoceras is a nautilid cephalopod included in the orthocerid family Baltoceratidae, widespread in the Middle Ordovician of North America, characterized by a depressed orthoconic shell with a subtriangular cross section and flattened venter and a proportionally large ventral siphuncle, 0.15 to 0.3 the dorso-ventral shell diameter. Septa are close spaced with sutures forming broad lobes on the upper flanks and ventral surface.

As originally perceived Murrayoceras included species differing in siphuncle profile. Those in which the siphuncle segments are externally convex were redefined as Cartersoceras., leaving Murrayoceras with those having essentially straight, tubular, or slightly concave segments.

Murrayoceras has a ventral rod in the siphuncle, putting it thereby in the rod-bearing Baltoceratidae, and closely related to Rhabdiferoceras and Cartersoceras, among others. In some recent classifications however Murrayoceras has been reassigned to the Sactorthoceratidae although Frey (1995) did retain the genus in the Baltoceratidae.

References

  1. W. M. Furnish and Brian Glennister, 1964. Nautiloidea- Ellesmerocerida; Treatise on Invertebrate Paleontology, Part K. Geol. Soc. of America and Univ. Kansas Press
  2. ^ Rousseau H Flower, 1964. The Nautiloid Order Ellesmeroceratida (Cephalopoda). New Mexico Bureau of Mines and Mineral Resources Memoir 12.
  3. B. Kröger, et al.2007. Early orthoceratoid cephalopods from the Argentine Precordillera (Lower-Middle Ordovician). Journal of Paleontology 81(6):1266-1283
  4. R. C. Frey. 1995. Middle and Upper Ordovician nautiloid cephalopods of the Cincinnati Arch region of Kentucky, Indiana, and Ohio. U.S. Geological Survey Professional Paper 1066P:1-126
Taxon identifiers
Murrayoceras
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