Oncoceratidae

The Middle Silurian Rizosceras indocile, from Sweet (1964).

Belongs within: Oncocerida.
Contains: Cyrtorizoceras, Brevicoceratidae, Nothoceratidae, Polyelasmoceratidae, Diestoceratidae, Hemiphragmoceratidae, Trimeroceratidae, Oncoceras, Acleistoceratidae, Poterioceratidae.

As defined by Sweet (1964), the Oncoceratidae is ancestral to a number of other oncocerid families; indeed, the oncoceratid lineage probably survives to the modern day in the Nautilidae. The Oncoceratidae excluding the descendant families were mostly cyrtoconic.

Characters (from Sweet 1964): Exogastric, ventromyarian brevicones and cyrtocones; siphuncle empty, on ventral side of chamber. Siphuncles suborthochoanitic and cylindrical in early stages of early forms, cyrtochoanitic with expanded segments in later stages and later forms. Connecting rings thin. Conch usually compressed, few species with circular or depressed section. Actinosiphonate deposits in a few advance forms.

<==Oncoceratidae [Maelonoceratidae, Melonoceratidae, Ooceratidae, Oocerinidae, Oonoceratidae, Rizoceratidae]
    |  i. s.: Asaphiceras Foerste 1928 S64
    |           `--*A. schucherti Foerste 1928 S64
    |         Beloitoceras Foerste 1924 S64
    |           |--*B. pandion (Hall 1861) [=Oncoceras pandion] S64
    |           |--B. fremontense Foerste 1935 P68
    |           |--B. landerense Foerste 1935 P68
    |           |--B. popoagiense Foerste 1935 P68
    |           `--B. ulrichi Flower 1946 P68
    |         Centrorizoceras Foerste 1930 S64
    |           `--*C. slocomi Foerste 1930 S64
    |         Cyrtorizoceras S64
    |         Digenuoceras Foerste 1935 S64
    |           `--*D. latum (Foerste 1929) [=Oxygonioceras latum] S64
    |         Dunleithoceras Foerste 1924 [=Dunleitoceras (l. c.)] S64
    |           `--*D. dunleithense (Miller & Gurley 1896) [=Cyrtoceras dunleithense] S64
    |         Ehlersoceras Foerste 1932 S64
    |           `--*E. huronense Foerste 1932 S64
    |         Ekwanoceras Foerste & Savage 1927 S64
    |           `--*E. breviconicum Foerste & Savage 1927 S64
    |         Kentlandoceras Foerste 1932 S64
    |           `--*K. shrocki Foerste 1932 [=K. schrocki] S64
    |         Loganoceras Foerste 1932 S64
    |           `--*L. regulare (Billings 1857) [=Cyrtoceras regulare] S64
    |         Maelonoceras Hyatt 1884 [=Meloceras (l. c.), Melonoceras (l. c.)] S64
    |           `--*M. praematurum (Billings 1860) [=Phragmoceras praematurum] S64
    |         Metarizoceras Foerste 1930 [incl. Cyclorizoceras Foerste 1930] S64
    |           |--*M. savagei Foerste 1930 S64
    |           `--M. erectum Foerste 1930 P68
    |         Miamoceras Flower 1946 S64
    |           `--*M. shideleri Flower 1946 S64
    |         Neumatoceras Foerste 1935 S64
    |           |--*N. gibberosum Foerste 1935 S64
    |           |--N. breviposticum P68
    |           |--N. canyonense Foerste 1935 P68
    |           |--N. milleri Foerste 1935 P68
    |           `--N. nutans S64
    |         Paroocerina Zhuravleva 1961 S64
    |           `--*P. podolskensis Zhuravleva 1961 S64
    |         Richardsonoceras Foerste 1932 S64
    |           |--*R. simplex (Billings 1857) [=Cyrtoceras simplex] S64
    |           |--R. subcuneatum Foerste 1935 P68
    |           `--R. wyomingense Foerste 1935 P68
    |         Rizosceras Hyatt 1884 [=Rizoceras Hyatt in Zittel 1900] S64
    |           |--*R. indocile (Barrande 1866) [=Orthoceras indocile] S64
    |           |--R. cyathus T64
    |           |--‘Rizoceras’ infundibuliforme Foerste 1936 P68
    |           |--R. parvulum T64
    |           |--‘Rizoceras’ pocilliforme Foerste 1936 P68
    |           `--R. zebra T64
    |         Romingoceras Foerste 1932 [=Romingeroceras (l. c.)] S64
    |           `--*R. josephianum Foerste 1932 S64
    |         Scofieldoceras Foerste 1932 [=Schofieldoceras (l. c.)] S64
    |           `--*S. shumardi (Clarke 1897) [=Cyrtoceras shumardi] S64
    |         Vaupelia Flower 1946 S64
    |           `--*V. russelli Flower 1946 S64
    |         Zittelloceras Hyatt 1884 [=Zitteloceras (l. c.); incl. Laphamoceras Foerste 1932] S64
    |           |--*Z. hallianum (d’Orbigny 1850) (see below for synonymy) S64
    |           `--Z. clarkeanum P68
    |--+--Brevicoceratidae S64
    |  |--Nothoceratidae S64
    |  |--Polyelasmoceratidae S64
    |  |--Oonoceras Hyatt 1884 [=Ooceras (l. c.); incl. Exomegoceras Miller & Carrier 1942, Exomeroceras (l. c.)] S64
    |  |    `--*O. acinaces (Barrande 1866) [=Cyrtoceras acinaces] S64
    |  `--Oocerina Foerste 1926 [=Oocenia (l. c.)] S64
    |       `--*O. lentigradum (Barrande 1866) [=Cyrtoceras lentigradum] S64
    `--+--Diestoceratidae S64
       |--Hemiphragmoceratidae S64
       |--Trimeroceratidae S64
       |--Oncoceras S64
       `--+--Acleistoceratidae S64
          |--Poterioceratidae S64
          `--Karoceratidae S64
               |--Osbornoceras Foerste 1936 S64
               |    `--*O. swinnertoni Foerste 1936 S64
               |--Shuranoceras Barskov 1959 S64
               |    `--*S. dolmatovi Barskov 1959 S64
               `--Karoceras Roussanoff 1909 S64
                    |--*K. laminare (Barrande 1877) [=Cyrtoceras laminare] S64
                    `--K. typicum S64

*Zittelloceras hallianum (d’Orbigny 1850) [=Cyrtoceras hallianum; incl. C. lamellosum Hall 1847 non de Verneuil 1842] S64

*Type species of generic name indicated

REFERENCES

[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.

[T64] Teichert, C. 1964. Morphology of hard parts. In Treatise on Invertebrate Paleontology pt. K. Mollusca 3. Cephalopoda – General Features – Endoceratoidea – Actinoceratoidea – Nautiloidea – Bactritoidea (R. C. Moore, ed.) pp. K13-K53. The Geological Society of America and the University of Kansas Press.