Iron Mountain Bed (Miocene of the United States)

Also known as Schooner Point

Where: Lincoln County, Oregon (44.7° N, 124.1° W: paleocoordinates 44.5° N, 118.0° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Astoria Formation, Burdigalian (20.4 - 16.0 Ma)

• early Miocene

•uncomformably overlain by Depoe Bay Basalt, dated at 16 +/- 0.65, 15.2 +/- 0.6, and 14.5 +/- 1.0 Ma using KA; dates are from different localities and it is not clear which is most relevant; old constants used

•overlain by the slightly higher Cape Foulweather Basalt = Gingko Basalt, dated at 15.4 +/- 0.3 Ma (mehtod?): Prothero et al. 2001

•in a reversed polarity zone interpreted as C5Cr: Prothero et al. 2001

• bed-level stratigraphic resolution

Environment/lithology: marine; concretionary, brown, gray sandstone

• "light-brown to dark-gray sandstone nodules": Prothero et al. 2001

Size class: macrofossils

Collection methods: surface (float)

Primary reference: M. C. Coombs. 1979. Tylocephalonyx, a new genus of North American dome-skulled chalicotheres (Mammalia, Perissodactyla). Bulletin of the American Museum of Natural History 164(1):1-64 [J. Alroy/J. Alroy/M. Uhen]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 18929: authorized by John Alroy, entered by John Alroy on 26.03.1995, edited by Mark Uhen

Creative Commons license: CC BY (attribution)

Taxonomic list

• see also Munthe and Coombs 1979
Mammalia
 Perissodactyla - Desmostylidae
Desmostylus hesperus6 Marsh 1888 desmostylian
 Perissodactyla - Chalicotheriidae
Tylocephalonyx sp. Coombs 1979 chalicothere
 Perissodactyla - Rhinocerotidae
Aphelops sp.8 Owen 1845 rhinoceros
"rhino"; Coombs' text post-dates Munthe and Coombs
 Carnivora -
Pteronarctos goedertae5 Barnes 1989 pinniped
several specimens in Berta 1994 have different locality descriptions, but all are about the same place
Pteronarctos piersoni n. sp.2 Barnes 1990 pinniped
Pacificotaria hadromma n. gen. n. sp.3 Barnes 1992 pinniped
 Carnivora - Odobenidae
Proneotherium repenningi n. gen. n. sp.7
Proneotherium repenningi n. gen. n. sp.7 Kohno et al. 1995 walrus
 Carnivora - Desmatophocidae
Desmatophoca oregonensis1 Condon 1906 pinniped
Allodesminae indet.4 Mitchell 1968 pinniped
 Mysticeti -
Cophocetus oregonensis9 Packard and Kellogg 1934 whale