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Temporal range: M Ordovician (M Chazyan)
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Nautiloidea
Order: Endocerida
Family: Endoceratidae
Genus: Chazyoceras
Flower, 1958

Chazyoceras ("Horn of the Chazyan") is a moderately large[specify] endocerid included in the Endoceratidae with a Nanno type apex and a ventral siphuncle with a holochoanitic (where "holo" is entire, and "choan" refers to its funnel-shaped opening) wall, characteristic of the family. The siphuncle swelling at the apex is subtriangular in longitudinal profile. The endocones are of medium length.

Chazyoceras was named by Rousseau Flower in 1958. The genotype is Chazyoceras valcourense which came from the Middle Chazyan (Lower Middle Ordovician) of Valcour Island on Lake Champlain. Chazyoceras resembles Perkinsoceras which Flower included in the Allotrioceratidae - a family which Flower named and included in the Endocerida based on the strange fossil, Allotrioceras

Both Chazyoceras and Perkinsoceras types are housed in the paleontology collection at the New Mexico Museum and Natural History and Science in Albuquerque, where they were transferred from Flower's collection at the New Mexico Bureau of Mines in Socorro.


  • Flower, R. H 1958. Some Chazyan and Mohawkian Endoceratida, Jour Paleon V 32, N.2, pp 433-458, May 1858.
  • Flower, R.H 1976 Some Whiterock and Chazy Endooceroids, Memoir 28, Part II, New Mexico Bureau of Mines and Mineral Resources, Socorro, New Mexico
  • Teichert, Curt 1964. Endoceratoidea; Treatise on Invertebrate Paleontology, Part K Mollusca 3; Geol Soc of America and University of Kansas Press