USGS Mesozoic 22871, Alzada (Cretaceous of the United States)

Where: Carter County, Montana (45.1° N, 104.5° W: paleocoordinates 44.6° N, 64.4° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Plesiacanthoceras wyomingense ammonoid zone, Middle Cenomanian (99.6 - 93.5 Ma)

• bed-level stratigraphic resolution

Environment/lithology: marine; lithified shale

Size class: macrofossils

Collected by J.B. Reeside, W.A. Cobban, H.R. Christner; reposited in the USNM

Primary reference: W. J. Kennedy and W. A. Cobban. 1990. Cenomanian micromorphic ammonites from the western interior of the USA. Palaeontology 33:379-422 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 175422: authorized by Matthew Clapham, entered by Matthew Clapham on 11.12.2015, edited by Pete Wagner

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Cephalopoda
 Ammonitida - Acanthoceratidae
"Plesiacanthoceras wyomingense" = Dunveganoceras (Plesiacanthoceras) wyomingense, Acanthoceratinae indet., Protacanthoceras alzadense n. sp., "Kastanoceras spiniger n. gen. n. sp." = Kastanoceras spinigerum, Plesiacanthoceratoides alzadense, Tarrantoceras sp., Tarrantoceras cuspidum, Alzadites alzadensis n. gen. n. sp.
"Plesiacanthoceras wyomingense" = Dunveganoceras (Plesiacanthoceras) wyomingense Reagan 1924 ammonite
Acanthoceratinae indet. de Groussouvre 1894 ammonite
Protacanthoceras alzadense n. sp. Cobban 1987 ammonite
"Kastanoceras spiniger n. gen. n. sp." = Kastanoceras spinigerum Kennedy and Cobban 1990 ammonite
Tarrantoceras sp. Stephenson 1955 ammonite
Tarrantoceras cuspidum Stephenson 1953 ammonite
Alzadites alzadensis n. gen. n. sp. Kennedy and Cobban 1990 ammonite
 Ammonitida - Desmoceratidae
Moremanoceras straini, Moremanoceras montanaense n. sp.
Moremanoceras straini Kennedy et al. 1988 ammonite
Moremanoceras montanaense n. sp. Kennedy and Cobban 1990 ammonite
 Ammonitida - Binneyitidae
Borissiakoceras orbiculatum
Borissiakoceras orbiculatum Stephenson 1955 ammonite
 Ammonitida - Scaphitidae
Scaphites (Scaphites) sp.
Scaphites (Scaphites) sp. Parkinson 1811 ammonite
 Ammonitida - Anisoceratidae
Idiohamites pulchellus n. sp., Idiohamites bispinosus n. sp.
Idiohamites pulchellus n. sp. Kennedy and Cobban 1990 ammonite
Idiohamites bispinosus n. sp. Kennedy and Cobban 1990 ammonite
 Ammonitida - Hamitidae
Hamites cimarronensis
Hamites cimarronensis Kauffman and Powell 1977 ammonite
Bivalvia
 Myalinida - Inoceramidae
Inoceramus prefragilis
Inoceramus prefragilis Stephenson 1952 clam