Belongs within: Nautilida.
Mostly known from the Lower Carboniferous (though a single genus, Apogonoceras, survived into the Lower Permian), the Trigonoceratidae were a morphologically diverse family of nautilid cephalopods. As well as more typical evolute forms, the Trigonoceratidae also included some genera (such as Choteauoceras and Rineceras) in which the shells were loosely coiled with successive whorls not remaining in contact with each other (Kummel 1964).
Characteristics (from Kummel 1964): Loosely coiled to evolute, with oval to subquadratic, depressed to compressed whorl sections, generally bearing longitundinal ridges that may decrease with growth. Suture usually only slightly sinuous. Siphuncle small, central, orthochoanitic.
<==Trigonoceratidae (see below for synonymy) |--Mesochasmoceras Foord 1900H99 | `--*M. latidorsatum (M’Coy 1844) [=Nautilus (Discites) latidorsatus]H99 |--Lispoceras Hyatt 1893K64 | `--*L. trivolve Hyatt 1893K64 |--Leuroceras Hyatt 1893K64 | `--*L. aplanatum Hyatt 1893K64 |--Diodoceras Hyatt in Zittel 1900K64 | `--*D. avonense (Dawson 1868)K64 [=Nautilus avonensisK64, Endolobus avonensisH84] |--Apogonoceras Ruzhentsev & Shimanskiy 1954K64 | `--*A. remotum Ruzhentsev & Shimanskiy 1954K64 |--Chouteauoceras Miller & Garner 1953K64 | `--*C. americanum (Miller & Furnish 1939) [=Rineceras americanum]K64 |--Pararineceras Turner 1954K64 | `--*P. luidi (Fleming 1828) [=Nautilus luidi]K64 |--Rineceras Hyatt 1893 [=Rhineceras Hyatt in Zittel 1900]K64 | |--*R. propinquum (de Koninck 1880)K64 [=Gyroceras propinquumK64, Triboloceras propinquumH84] | `--R. digonumP68 |--Discitoceras Hyatt 1884H99 [=Discites M’Coy 1844 nec Schlotheim 1813 nec de Haan 1825K64] | |--*D. costellatum (M’Coy 1844)H99 [=Nautilus (*Discites) costellatusH99, H84, Discitoceras costellatus (l. c.)H99] | |--‘Discites’ nikitowkensisG31 | `--D. texanum Miller & Youngquist 1948P68 |--Trigonoceras M’Coy 1844H99 [incl. Nautiloceras d’Orbigny 1849K64] | |--*T. paradoxicum (Sowerby 1825)H99 (see below for synonymy) | |--T. asselberghsi Maillieux 1925H99 | `--T. visetense Maillieux 1925H99 |--Subclymenia d’Orbigny 1849K64 | |--S. evoluta (Phillips 1836) [=Goniatites evolutus]K64 | |--S. gibbosaK64 | `--S. occulataK64 |--Stroboceras Hyatt 1884K64 | |--*S. hartii (Dawson 1868)K64 [=Gyroceras hartiiK64, Discites hartiiH84] | |--S. bisulcatumK64 | |--S. crispum Gordon 1957P68 | `--S. stygialeK64 |--Thrincoceras Hyatt 1893H99 [incl. Neothrincoceras Ruzhentsev & Shimanskiy 1954K64] | |--*T. depressum Hyatt 1893H99 | |--T. hibernicum (Foord 1891) [=Gyroceras hibernicum, Rineceras hibernicum]H99 | |--T. hyatti Foord 1900H99 | |--T. kentuckiense Hyatt 1893H99 | `--T. uralicumG31 |--Maccoyoceras Miller, Dunbar & Condra 1933H99 | |--*M. discors (M’Coy 1844) [=Nautilus (Discites) discors, Discitoceras discors]H99 | |--M. discoidale (Winchell 1862)H99 | |--M. leveilleanum (de Koninck 1844) [=Nautilus leveilleanus, Discites leveilleanus, Discitoceras leveilleanum]H99 | |--M. oppaviense (Patteisky 1930)H99 | `--M. wrightii (Foord 1900) [=Discitoceras wrightii]H99 |--Aphelaeceras Hyatt 1884H99 [=Apheleceras (l. c.)K64] | |--*A. disciformis (Meek & Worthen 1873) [=Nautilus (Discites) disciformis]H99 | |--A. arkansanum Gordon 1964H99 | |--A. difficile (de Koninck 1878)H99 [=Nautilus difficilisH84] | |--A. discoideum (de Konick 1878)H99 | |--A. discus (Sowerby 1813)H99 | |--A. exaratum (de Koninck 1878)H99 | |--A. hibernicum (Foord & Crick 1893) [=Discites hibernicus, Apheleceras (l. c.) hibernicus]H99 | |--A. mosquense Tzwetaev 1888H99 | |--A. mutabile (M’Coy 1844) (see below for synonymy)H99 | `--A. trochlea (M’Coy 1844) [=Nautilus (Discites) trochlea, Apheleceras (l. c.) trochlea]H99 |--Epistroboceras Turner 1954H99 | |--*E. stubblefieldi Turner 1954H99 | |--E. chancharense Shimansky 1967H99 | |--E. crassum (Foord 1900) [=Stroboceras crassum]H99 | |--E. gracile Shimansky 1967H99 | |--E. kathleenae Ramsbottom & Moore 1961H99 | |--E. phillipsianum (Orbigny 1850)H99 | |--E. sulcatum (Sowerby 1826)H99 (see below for synonymy) | | |--E. s. sulcatumH99 | | `--E. s. castletonense Turner 1965H99 | `--E. sulcifer (Léveillé 1835)H99 `--Vestinautilus Ryckholt 1852H99 [incl. Triboloceras Hyatt in Zittel 1884K64] |--*V. koninckii (Orbigny 1850) [=Nautilus koninckii]H99 |--V. altidorsalis Winchell 1862H99 |--V. biangulatus (Sowerby 1825)H99 |--V. cariniferus (Sowerby 1824) (see below for synonymy)H99 |--‘Triboloceras’ digonumP68 |--V. formosus (Foord 1900) [=Triboloceras formosum; incl. Nautilus (Temnocheilus) crenatus M’Coy 1844 (n. d.)]H99 |--V. globatusH84 |--‘Nautilus’ meyerianus [=Triboloceras meyerianum]H84 |--V. multicarinatus (Sowerby 1825) (see below for synonymy)H99 |--V. paucicarinatus (Foord 1900) [=Coelonautilus paucicarinatus]H99 |--V. pinguis (de Koninck 1843) [=Nautilus pinguis, Coelonautilus pinguis]H99 |--V. semiglaber Foord 1900H99 |--V. semiplicatus (Foord 1900)H99 `--‘Gyroceras’ serratum [=Triboloceras serratum]H84
Aphelaeceras mutabile (M’Coy 1844) [=Nautilus (Discites) mutabilis, Aphelaeceras mutabilis (l. c.), Apheleceras (l. c.) mutabile]H99
Epistroboceras sulcatum (Sowerby 1826)H99 [=Nautilus sulcatusH99, Discitoceras sulcatumK64, N. (Discites) sulcatusH99, Stroboceras sulcatumH99]
Trigonoceratidae [Aphelaeceratinae, Neothrincoceratidae, Rhineceratidae, Rineceratidae, Subclymeniidae, Thrincoceratidae, Tribolocerataceae, Triboloceratidae]
*Trigonoceras paradoxicum (Sowerby 1825)H99 [=Orthocera paradoxicaH99, Gyroceras paradoxicumH84, Orthoceras (Trigonoceras) paradoxicumH99; incl. G. aigocerasH84, *Nautiloceras aigocerasH84]
Vestinautilus cariniferus (Sowerby 1824) [=Nautilus cariniferus, Coelonautilus cariniferus, N. (Temnocheilus) cariniferus]H99
Vestinautilus multicarinatus (Sowerby 1825) [=Nautilus multicarinatus, Coelonautilus multicarinatus; incl. N. (Temnocheilus) porcatus M’Coy 1844]H99
*Type species of generic name indicated
References
[G31] Grabau, A. W. 1931. The Permian of Mongolia: A report on the Permian fauna of the Jisu Honguer limestone of Mongolia and its relations to the Permian of other parts of the world. American Museum of Natural History: New York.
[H99] Histon, K. 1999. A revision of A. H. Foord’s monograph of Irish Carboniferous nautiloid cephalopods (1897–1901). Part 2. Monograph of the Palaeontographical Society 153: 63–129.
[h84] Hyatt, A. 1883–1884. Genera of fossil cephalopods. Boston Soc. Nat. History, Proc. 22: 253–338.
[K64] Kummel, B. 1964. Nautiloidea—Nautilida. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt K. Mollusca 3. Cephalopoda—General Features—Endoceratoidea—Actinoceratoidea—Nautiloidea—Bactritoidea pp. K383–K457. 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.