Valcourocratidae

The Valcouroceratidae is a family within the Oncocerida, nautiloid cephalopods from the middle and upper Ordovician, established by Rousseau Flower in 1945.

Valcourocratidae Temporal range: M-U Ordovician
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Order:	†Oncocerida
Family:	†Valcouroceratidae Flower (1945)
Genera
See text

Diagnosis

Valcouroceratids are characterized by exogastric cyrtocones and brevicones that change during the life span from compressed to depressed or subtriangular in cross section, and which have ventral siphuncles that are cyrtochoanitic and which contain lammelar actinosiphonate fillings. The actinosiphonate fillings, commonly referred to as deposits, are radially inward projections of the connecting rings that extend longitudinally along the inner wall of the siphuncle and project forward as blades into the siphuncle interior from the septal foremina.(Sweet 1964, Flower 1950)

Distribution

Most valcouroceratids come from North America but Valcouroceras has been found in northern Europe (Norway) as well. (Sweet 1964)

Genera

The Valcouroceratidae includes 8 genera:

• Valcouroceras
• Actinomorpha
• Augustoceras
• Fayettoceras
• Kindeloceras
• Manitoulinceras
• Minganoceras
• Staufferoceras

References

• Flower, R.H. 1950. (Flower and Kummel) A Classification of the Nautiloidea; Journal of Paleontology, Vol 24, no 5, pp 604–616, Sept 1950
• Sweet, W.C. 1964. Nautiloidea-Oncoverida; Treatise on Invertebrate Paleontology Part K, Mollusca 3. Geol Soc of America and Univ Kansas press; R.C. Moore, ed.