Current Taxonomic Status of Late Cretaceous Ammonoid Species from the Western Interior Seaway Assigned to the Family Placenticeratidae (Ammonitina: Hoplitaceae)
Jonathan R. Hendricks
Paleontological Research Institution, Ithaca, New York
Note: Names in green are accepted; names in red are synonyms. Return to main list here. This page was last updated July 12, 2017.
Class Cephalopoda
Order Ammonoidea Zittel, 1884
Suborder Ammonitina Hyatt, 1889
Superfamily Hoplitaceae H. Douvillé
Duration: Upper Aptian to Upper Maastrichtian (Source: Wright et al., 1996).
Family Placenticeratidae Hyatt, 1900
Duration: Upper Aptian to Upper Maastrichtian (Source: Wright et al., 1996).
Genus Placenticeras Meek, 1876
Type species: Ammonitesplacenta DeKay, 1828
Duration: Upper Albian to Lower Campanian (Wright et al., 1996).
Placenticeras cumminsi Cragin, 1893
Original presentation: Placenticeras syrtalis var. cumminsi
Original publication: Cragin. 1893. [p. 237].
Types: awaiting determination.
Type locality: Dallas County, Texas (Cobban and Hook, 1983).
Type horizon: Britton Formation (Cobban and Hook, 1983).
Other specimens: USNM 328709-328712.
WIS occurrences:
Turonian: Mancos Shale (Rio Salado Tongue) (NM).
Cenomanian: Britton Formation (TX).
PaleoDB taxon number: 143708.
Synonyms: Placenticeras placenta (DeKay) of Stanton (1894, figs 2 and 3 only) (source: Cobban and Hook, 1983); Placenticeras stantoni Hyatt, 1903 (source: Cobban and Hook, 1983); Placenticeras stantoni var. bolli Hyatt, 1903 (source: Cobban and Hook, 1983); Placenticeras pseudoplacenta Hyatt, 1903 (not pl. 44) (source: Cobban and Hook, 1983); Placenticeras pseudoplacenta var. occidentale Hyatt, 1903 (pl. 45, fig. 2 only) (source: Cobban and Hook, 1983).
References: Cobban and Hook (1983).
Placenticeras placenta Dekay
Placenticeras pseudoplacenta Hyatt, 1903
Placenticeras stantoni Hyatt, 1903
Placenticeras stantoni var. bolli Hyatt, 1903
Placenticeras syrtale (Morton, 1834)
Original presentation: Ammonites syrtalis
Original publication: Morton. 1834. [p. 40, pl. 16, fig. 4].
Holotype: “by monotypy, is the original of Morton, 1834”; ANSP 282 (Kennedy et al., 2001, p. 4).
Type locality: Green County, Alabama (Kennedy et al., 2001).
Other specimens: USNM 490961-490969.
WIS occurrences:
Santonian: Blossom Sand (TX).
Other occurrences:
“The species ranges from upper Santonian to lower Campanian, and is known from northern Mexico, Texas, Alabama, Mississippi, New Mexico, Colorado, Wyoming, Montana, and Utah” (Kennedy et al., 2001, p. 7).
PaleoDB taxon number: 131030.
References: Kennedy et al. (2001).