Sactorthoceratidae

Various views of the ascocerid Choanoceras mutabile, possibly the most obscene cephalopod ever. Figure from Furnish & Glenister (1964).

Belongs within: Michelinoceratida.

The Middle Ordovician to Upper Silurian sactorthoceratid lineage includes the paraphyletic Sactorthoceratidae, Clinoceratidae and Ascocerida. The Sactorthoceratidae and Clinoceratidae were orthoconic or cyrtoconic longicones without endosiphuncular or cameral deposits (Sweet 1964). Septal necks were orthochoanitic or suborthochoanitic in Sactorthoceratidae and Ascocerida, cyrtochoanitic in Clinoceratidae (Furnish & Glenister 1964, Sweet 1964). Ascocerids were distinguished by inflated siphuncles and the periodic shedding of the apical parts of the conch; in the Ascoceratidae, the adoral portion of the conch became greatly swollen, followed by shedding of the juvenile section of the conch to produce a breviconic adult form (Furnish & Glenister 1964).

See also: The floating egg.

<==Sactorthoceratidae
    |--Sactorthoceras Kobayashi 1934 [incl. Sigmorthoceras Kobayashi 1934] S64
    |    `--*S. gonioseptum Kobayashi 1934 S64
    |--Sigmocycloceras Kobayashi 1934 S64
    |    `--*S. kogenense (Kobayashi 1927) [=Protocycloceras kogenense] S64
    `--+--Centroonoceras Kobayashi 1934 [incl. Cyrtoonoceras Flower 1939] S64
       |    `--*C. tokunagai (Kobayashi 1927) [=Ooceras tokunagai] S64
       `--+--Clinoceratidae S64
          |    |--Whiteavesites Foerste 1929 S64
          |    |    `--*W. winnipegense (Whiteaves 1892) [=Orthoceras winnipegense] S64
          |    |--Clinoceras Mascke 1876 [=Clynoceras (l. c.)] S64
          |    |    |--*C. dens Mascke 1876 S64
          |    |    `--C. exiguum P68
          |    `--Whitfieldoceras Foerste 1932 S64
          |         |--*W. mumiaeforme (Whitfield 1882) [=Oncoceras mumiaeforme] S64
          |         |--W. baffinense Foerste 1932 P68
          |         |--W. minimum Foerste 1935 P68
          |         `--W. trentonense Foerste 1932 P68
          `--Ascocerida [Ascoceracea, Ascoceratina, Ascoceratida, Ecdyceratida, Mixochoanites] S64
               |--Choanoceras Lindström 1890 (see below for synonymy) FG64
               |    `--*C. mutabile Lindström 1890 FG64
               |--Hebetoceratidae FG64
               |    |--Hebetoceras Flower 1941 FG64
               |    |    `--*H. mirandum Flower 1941 FG64
               |    |--Ecdyceras Flower 1941 [incl. Pachecdyceras Flower 1947] FG64
               |    |    `--*E. sinuiferum Flower 1941 FG64
               |    `--Montyoceras Flower 1941 FG64
               |         `--*M. arcuatum Flower 1941 FG64
               `--Ascoceratidae [Ascocératides] FG64
                    |--Probillingsitinae FG64
                    |    |--Shamattawaceras Foerste & Savage 1927 FG64
                    |    |    `--*S. ascoceroides Foerste & Savage 1927 FG64
                    |    `--Probillingsites Foerste 1928 FG64
                    |         |--*P. welleri Foerste 1928 FG64
                    |         |--P. belli Miller, Youngquist & Collinson 1954 P68
                    |         |--P. milleri Foerste 1935 P68
                    |         |--P. pronis FG64
                    |         `--P. sutherlandi FG64
                    `--Ascoceratinae [Schuchertoceratidae] FG64
                         |--Aphragmites Barrande 1865 FG64
                         |    `--*A. buchi (Barrande 1855) [=Ascoceras buchi] FG64
                         |--Lindstroemoceras Miller 1932 FG64
                         |    `--*L. dolium (Lindström 1890) [=Ascoceras dolium] FG64
                         |--Glossoceras Barrande 1865 FG64
                         |    |--*G. gracile (Barrande 1865) [=Ascoceras (*Glossoceras) gracile] FG64
                         |    `--G. lindstroemi FG64
                         |--Billingsites Hyatt 1884 [=Billingoceras (l. c.)] FG64
                         |    |--*B. canadensis (Billings 1857) [=Ascoceras canadense] FG64
                         |    |--B. landerensis Foerste 1835 P68
                         |    `--B. williamsportensis Foerste 1924 P68
                         |--Schuchertoceras Miller 1932 FG64
                         |    |--*S. anticostiense (Billings 1866) [=Ascoceras anticostiense] FG64
                         |    |--S. newberryi FG64
                         |    `--S. thomasi [=S. iowaense] FG64
                         |--Ascoceras Barrande 1847 (see below for synonymy) FG64
                         |    |--*A. bohemicum Barrande 1855 FG64
                         |    |--A. collare FG64
                         |    |--A. lagena FG64
                         |    `--A. manubrium FG64
                         `--Parascoceras Miller 1932 [incl. Pseudascoceras Miller 1932, Pseudoscoceras (l. c.)] FG64
                              |--*P. fistula (Lindström 1890) [=Ascoceras fistula] FG64
                              |--P. decipiens FG64
                              |--P. pupa FG64
                              `--P. sipho FG64

Ascoceras Barrande 1847 [=Asoceras (l. c.), Cryptoceras Barrande 1846 (n. n.) non Latreille 1804] FG64

Choanoceras Lindström 1890 [=Choaniceras Lindström 1888 (n. n.), Choniceras (l. c.), Coanoceras (l. c.); Choanoceratidae] FG64

*Type species of generic name indicated

REFERENCES

[FG64] Furnish, W. M., & B. F. Glenister. 1964. Nautiloidea – Ascocerida. In Treatise on Invertebrate Paleontology pt. K. Mollusca 3. Cephalopoda – General Features – Endoceratoidea – Actinoceratoidea – Nautiloidea – Bactritoidea (R. C. Moore, ed.) pp. K261-K277. The Geological Society of America and the University of Kansas Press.

[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 – Orthocerida. In Treatise on Invertebrate Paleontology pt. K. Mollusca 3. Cephalopoda – General Features – Endoceratoidea – Actinoceratoidea – Nautiloidea – Bactritoidea (R. C. Moore, ed.) pp. K216-K261. The Geological Society of America and the University of Kansas Press.