Augustoceras shideleri. Photo from UGA Stratigraphy Lab.

Belongs within: Oncocerida.

The Valcouroceratidae were mostly breviconic (short-shelled) oncocerid cephalopods from the Middle to Upper Ordovician. In mature individuals, bladelike lamellae called actinosiphonate deposits developed within the siphuncle (Sweet 1964).

Characteristics (from Sweet 1964): Exogastric cyrtocones and brevicones with ventral, actinosiphonate siphuncle; conch changes during ontogeny from compressed to depressed or subtriangular section.

    |--Actinomorpha Flower 1943 S64
    |    `--*A. pupa Flower 1943 S64
    |--Augustoceras Flower 1946 S64
    |    `--*A. shideleri Flower 1946 S64
    |--Kindleoceras Foerste 1924 S64
    |    `--*K. reversatum Foerste 1924 S64
    |--Manitoulinoceras Foerste 1924 S64
    |    `--*M. lysander (Billings 1865) [=Cyrtoceras lysander] S64
    |--Minganoceras Foerste 1938 S64
    |    `--*M. subturbinatum (Billings 1857) [=Cyrtoceras subturbinatum] S64
    |--Staufferoceras Foerste 1932 S64
    |    `--*S. featherstonhaughi (Clarke 1897) [=Cyrtoceras featherstonhaughi] S64
    |--Valcouroceras Flower 1943 S64
    |    |--*V. bovinum Flower 1943 S64
    |    `--V. elongatum Flower 1952 P68
    `--Fayettoceras Foerste 1932 S64
         |--*F. thompsoni (Miller 1894) [=Cyrtoceras thompsoni] S64
         |--F. beloitense Foerste 1932-1933 P68
         `--F. canyonense Foerste 1935 P68

*Type species of generic name indicated


[P68] Purnell, L. R. 1968. Catalog of the Type Specimens of Invertebrate Fossils. Part I: Paleozoic Cephalopoda. United States National Museum Bulletin 262: 1-198.

[S64] Sweet, W. C. 1964. Nautiloidea – Oncocerida. In Treatise on Invertebrate Paleontology pt. K. Mollusca 3. Cephalopoda – General Features – Endoceratoidea – Actinoceratoidea – Nautiloidea – Bactritoidea (R. C. Moore, ed.) pp. K277-K319. The Geological Society of America and the University of Kansas Press.

No comments:

Post a Comment

Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="">FoS</a> = FoS