The Valcouroceratidae is a family within the

Oncocerida The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous; one possible member is known from the Early Permian), in which the connecting rings are t ...

nautiloid Nautiloids are a group of marine cephalopods ( Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species ...

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s from the middle and upper

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

, established by

Rousseau Flower Rousseau Hayner Flower (1913–1988) was an extremely prolific 20th century paleontologist, known for his eccentric personality. Career Although trained as an entomologist, and a specialist in dragonflies and orthopterans, Flower began stud ...

in 1945.

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

siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ...

s that are cyrtochoanitic and which contain lamellar 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 foramina.(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'' *'' Kindleoceras'' *'' Manitoulinoceras'' *'' Minganoceras'' *'' Staufferoceras'' The Valcouroceratidae comprises eight genera, three of which, ''Valcouroceras'', ''Augustoceras'', and ''Actinomorpha'', were named by Flower in 1943 and 1946 and five of which, ''Fayettoceras'', ''Kindleoceras'', ''Manitoulinoceras'', ''Minganoceras'', and ''Staufferoceras'', were named previously by Foeste between 1924 and 1938. Flower established the family Valcouroceratidae in 1945, based on Valcouroceras, which he named in 1943. All eight genera were included as late as 1950 where they rest today.

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 The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

Part K, Mollusca 3. Geol Soc of America and Univ Kansas press; R.C. Moore, ed.

External links

* Flower, R. H. and Kummel B, 1950; A Classification of the Nautiloidea; ''Journal of Paleontology'' V 24 n.5 Sept 1950 * Sweet, W. C. 1964; Nautiloidea-Oncocerida, in the Treatise on Invertebrate Paleontology; Geological Society of America and University of Kansas Press.
Valcouroceratidae -Paleobio db
{{Taxonbar, from1=Q7909339, from2=Q7909340 Prehistoric nautiloid families Ordovician cephalopods Middle Ordovician first appearances Late Ordovician extinctions Taxa named by Rousseau H. Flower Oncocerida