Bactritida

Fossil of Bactrites preserved in pyrite. Photo by Qurum.

Belongs within: Cephalopoda.
Contains: Ammonoidea, Coleoidea.

The Bactritida were a group of mostly straight-shelled cephalopods (some forms were curved) first appearing in the Ordovician. Bactritids had a globular protoconch separated by a distinct constriction from the younger shell. The bactritids include the ancestors of the ammonoids and coleoids, with the latter surviving to the present day.

Characters (from Erben 1964, excluding ammonoids and coleoids): Conch orthoconic to cyrtoconic, longiconic to breviconic, with small or large apical angle. Siphuncle narrow, in contact with ventral wall; septal necks orthochoanitic to cyrtochoanitic. Suture with V-shaped ventral lobe. Protoconch globular to egg-shaped.

<==Bactritida (see below for synonymy)
    |  i. s.: Cochleiferoceras Shimanskiy 1962 E64
    |           `--*C. cochleiferum (Sandberger & Sandberger 1852) [=Orthoceras cochleiferum] E64
    |         Cyclobactrites Shimanskiy 1955 E64
    |           `--*C. erbeni Shimanskiy 1955 E64
    |         Devonobactrites Shimanskiy 1962 E64
    |           `--*D. obliquiseptatus (Sandberger & Sandberger 1852) [=Orthoceratites obliquiseptatum] E64
    |--Eobactrites Schindewolf 1932 E64
    |    `--*E. sandbergeri (Barrande 1867) [=Bactrites sandbergeri] E64
    `--+--Kokenia Holzapfel 1895 E64
       |    `--*K. obliquecostata Holzapfel 1895 E64
       |--Sicilioceras Shimanskiy 1954 E64
       |    `--*S. paternoi (Gemmellaro 1887) [=Orthoceras paternoi] E64
       |--Pseudobactrites Ferronnière 1921 [incl. Bojobactrites Horný 1957] E64
       |    |--*P. bicarinatus Ferronnière 1921 [incl. Bojobactrites ammonitans Horný 1957] E64
       |    `--P. peneaui E64
       |--Protobelemnoidea [Aulacoceratida] E64
       |    |--Choanoteuthis E64
       |    `--Aulacoceras E64
       |--Ctenobactrites Shimanskiy 1951 E64
       |    |--*C. (Ctenobactrites) costatus Shimanskiy 1951 E64
       |    `--C. (Mirites Shimanskiy 1962) E64
       |         `--C. (*M.) mirus Shimanskiy 1954 E64
       |--+--Lobobactrites Schindewolf 1932 E64
       |  |    |--*L. ellipticus (Frech 1897) (see below for synonymy) E64
       |  |    `--L. timanicus E64
       |  `--+--Ammonoidea E64
       |     `--Cyrtobactrites Erben 1960 E64
       |          |--*C. sinuatus Erben 1960 E64
       |          `--C. asinuatus E64
       |--+--Coleoidea E64
       |  `--Parabactritidae [Parabactritaceae] E64
       |       |  i. s.: ‘Orthoceras’ pygmaeum E64
       |       |--Tabantaloceras Shimanskiy 1954 E64
       |       |    `--*T. planum Shimanskiy 1954 E64
       |       |--Aktastioceras Shimanskiy 1948 E64
       |       |    `--*A. kruglovi Shimanskiy 1948 E64
       |       |--Parabactrites Shimanskiy 1948 E64
       |       |    `--*P. ruzhencevi Shimanskiy 1948 E64
       |       |--Microbactrites Shimanskiy 1954 E64
       |       |    `--*M. scorobogatovae Shimanskiy 1954 E64
       |       `--Belemnitomimus Shimanskiy 1954 E64
       |            `--*B. palaeozoicus Shimanskiy 1954 E64
       `--Bactrites Sandberger 1843 [incl. Hemibactrites Shimanskiy 1954; Stenoceras d’Orbigny 1849] E64
            |--*B. subconicus Sandberger 1843 E64
            |--B. aciculum E64
            |--B. ausavensis E64
            |--B. buedesheimensis E64
            |--B. carbonarius P68
            |--B. gaitherensis Gordon 1964 P68
            |--B. gracilior E64
            |--B. nevadensis E64
            |--B. primus E64
            |--B. quadrilineatus P68
            |--B. redactus Gordon 1964 P68
            |--B. schlotheimi E64
            |--B. smithianus Girty 1909 P68
            |--B. tenuicinctum P68
            `--B. warthini Miller 1938 P68

Bactritida [Bactritacea, Bactritaceae, Bactritidae, Bactritina, Bactritoidea, Bojobactritidae, Ctenobactritidae, Lobobactritidae]

*Lobobactrites ellipticus (Frech 1897) [=Bactrites ellipticus; incl. B. carinatus Sandberger & Sandberger 1852 non Orthoceratites carinatus Münster 1840] E64

*Type species of generic name indicated

REFERENCES

[E64] Erben, H. K. 1964. Bactritoidea. In Treatise on Invertebrate Paleontology pt. K. Mollusca 3. Cephalopoda – General Features – Endoceratoidea – Actinoceratoidea – Nautiloidea – Bactritoidea (R. C. Moore, ed.) pp. K491-K505. 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.