Astoria Formation

Astoria Formation
Astoria Formation
Stratigraphic range: Miocene
Type	Geological formation
Sub-units	From top to bottom: Big Creek sandstone member; Newport sandstone member; Silver Point mudstone member; Angora Peak sandstone member;
Underlies	Montesano Formation
Overlies	Lincoln Creek Formation
Location
Region	Washington, Oregon
Country	United States

Last updated October 08, 2025

The Astoria Formation (formerly known as the Astoria shales) is a geologic formation in Washington state & Oregon. It preserves fossils dating back to the early to middle Miocene (but was formerly thought to date to the Oligocene).^[1]

Description

The Astoria Formation is a thick marine formation representing a near shore, relatively shallow-water shelf deposit.^[2] The formation spans a considerable amount of time, with its base considered to be lower boundary of Newportian Stage (late Early Miocene) & its top to be upper boundary of Newportian Stage (middle Middle Miocene).^[1]

Fossil content

Color key

Taxon	Reclassified taxon	Taxon falsely reported as present	Dubious taxon or junior synonym	Ichnotaxon	Ootaxon	Morphotaxon

Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.

Mammals

Carnivorans

Genus	Species	Stratigraphy	Material	Notes
Desmatophoca	D. brachycephala	East of Knappton, Washington.^[3]	Skull elements.^[3]	A desmatophocid.
Desmatophoca	D. oregonensis	Iron Mountain Bed & an unspecified horizon.^[3]^[4]	Multiple specimens.^[3]^[4]	A desmatophocid.
Enaliarctos	E. emlongi	South of Big Creek, Lincoln County, Oregon.^[5]	USNM 250345.^[5]	A pinnipedimorph, may instead be from the Nye Mudstone.^{[ citation needed ]}
Enaliarctos	E. sp.	Iron Mountain bed, Lincoln County, Oregon.^[6]	Partial skeleton (UWBM 89114).^[6]	A pinnipedimorph.
Eodesmus	E. condoni	Iron Mountain Bed, Oregon.^[7]	A nearly complete cranium.^[7]	A desmatophocid.
Pacificotaria	P. hadromma	Iron Mountain bed, Lincoln County, Oregon.^[8]	Complete cranium (LACM 127973).^[8]	A pinnipedimorph.
Proneotherium	P. repenningi	Lincoln County, Oregon.^[9]	Remains of multiple individuals.^[9]	An odobenid.
Pteronarctos	P. goedertae	Lincoln County, Oregon.^[10]	Skulls.^[10]	A pinnipedimorph.

Cetaceans

Genus	Species	Presence	Material	Notes
Cophocetus	C. oregonensis	North of Yaquina Bay.^[4]	Associated skull, jaws & skeletal elements.^[4]	A baleen whale.
Dilophodelphis	D. fordycei	Nye Beach, Oregon.^[11]	USNM 214911.^[11]	A platanistid.
Wimahl	W. chinookensis	Washington State ^[12]		A kentriodontid.
Zarhinocetus	Z. donnamatsonae	Near Elma, Washington.^[2]	UCMP 86139.^[2]	An allodelphinid.

Perissodactyls

Genus	Species	Presence	Material	Notes	Images
Aphelops	A. sp.		Fragment of skull (USNM 187123).^[4]	A rhinoceros.
Tylocephalonyx	T. sp.	Iron Mountain Bed, Lincoln County, Oregon.^[13]	A skull (NMNH 187129).^[13]	A chalicothere.

Birds

Genus	Species	Presence	Material	Notes	Images
Diomedeidae	Gen. et. sp. indet.	East of Knappton, Washington.^[14]	Partial skeleton (SMF Av 644).^[14]	An albatross.

Cartilaginous fish

Genus	Species	Presence	Material	Notes
Carcharodon	C. megalodon	North of Newport, Oregon.^[15]		Species reassigned to the genus Otodus .
Cetorhinus	C. piersoni	North of Newport, Oregon.^[16]	Teeth.^[16]	A basking shark.
Cosmopolitodus	C. hastalis	Coos Bay, Oregon.^[15]	A tooth.^[15]	A lamnid shark.
Cosmopolitodus	C. planus?	North of Newport, Oregon.^[15]		A lamnid shark.
Galeocerdo	G. cf. aduncus	North of Newport, Oregon.^[15]		A requiem shark.
Hexanchus		North of Newport, Oregon.^[15]		A cow shark.
Isurus	I. hastalis	Coos Bay, Oregon.^[15]	A tooth.^[15]	Species reassigned to Cosmopolitodus .
Isurus	I. planus?	North of Newport, Oregon.^[15]		Species reassigned to Cosmopolitodus .
Myliobatis		North of Newport, Oregon.^[15]		An eagle ray.
Otodus	O. megalodon	North of Newport, Oregon.^[15]		Originally reported as Carcharodon megalodon.

References

1 2 3 "Geolex — Astoria publications". ngmdb.usgs.gov. Retrieved 2022-12-19.
1 2 3 4 5 Toshiyuki, Kimura; Barnes, Lawrence G. (March 2016). "New Miocene fossil Allodelphinidae (Cetacea, Odontoceti, Platanistoidea) from the North Pacific Ocean". Bull.Gunma Mus.Natu.Hist. 20: 1–58.
1 2 3 4 Barnes, Lawrence G. (1987-06-18). "An Early Miocene pinniped of the genus Desmatophoca (Mammalia: Otariidae) from Washington". Contributions in Science. 382: 1–20. doi: 10.5962/p.208126 . ISSN 0459-8113. S2CID 198245103.
1 2 3 4 5 Ray, Clayton E. (1976). "Fossil Marine Mammals of Oregon". Systematic Zoology. 25 (4): 420–436. doi:10.2307/2412515. ISSN 0039-7989. JSTOR 2412515.
1 2 Berta, Annalisa (1991). "New Enaliarctos* (Pinnipedimorpha) from the Oligocene and Miocene of Oregon and the Role of "Enaliarctids" in Pinniped Phylogeny". Smithsonian Contributions to Paleobiology. 69 (69): 1–33. doi:10.5479/si.00810266.69.1. hdl:10088/19145.
1 2 Poust, Ashley; Boessenecker, Robert (2018). "Expanding the geographic and geochronologic range of early pinnipeds: new specimens of Enaliarctos from Northern California and Oregon". Acta Palaeontologica Polonica. 63. doi: 10.4202/app.00399.2017 . S2CID 55978096.
1 2 Tate-Jones, M. Kellum; Peredo, Carlos M.; Marshall, Christopher D.; Hopkins, Samantha S. B. (2020-07-03). "The Dawn of Desmatophocidae: A New Species of Basal Desmatophocid Seal (Mammalia, Carnivora) from the Miocene of Oregon, U.S.A." . Journal of Vertebrate Paleontology. 40 (4) e1789867. Bibcode:2020JVPal..40E9867T. doi:10.1080/02724634.2020.1789867. ISSN 0272-4634. S2CID 224935328.
1 2 Barnes, Lawrence G. (1992-04-07). "A new genus and species of Middle Miocene enaliarctine pinniped (Mammalia, Carnivora, Otariidae) from the Astoria Formation in coastal Oregon". Contributions in Science. 431: 1–27. doi: 10.5962/p.208159 . ISSN 0459-8113. S2CID 199822990.
1 2 Deméré, Thomas A.; Berta, Annalisa (2001-07-20). "A reevaluation of Proneotherium repenningi from the Miocene Astoria Formation of Oregon and its position as a basal odobenid (Pinnipedia: Mammalia)". Journal of Vertebrate Paleontology. 21 (2): 279–310. doi:10.1671/0272-4634(2001)021[0279:AROPRF]2.0.CO;2. ISSN 0272-4634. S2CID 88095414.
1 2 Berta, Annalisa (1994). New specimens of the Pinnipediform Pteronarctos from the Miocene of Oregon. Washington, D.C: Smithsonian Institution Press.
1 2 Boersma, Alexandra T.; McCurry, Matthew R.; Pyenson, Nicholas D. (May 2017). "A new fossil dolphin Dilophodelphis fordycei provides insight into the evolution of supraorbital crests in Platanistoidea (Mammalia, Cetacea)". Royal Society Open Science. 4 (5) 170022. Bibcode:2017RSOS....470022B. doi:10.1098/rsos.170022. ISSN 2054-5703. PMC 5451807 . PMID 28573006.
↑ Peredo, Carlos Mauricio; Uhen, Mark D.; Nelson, Margot D. (2018-03-04). "A new kentriodontid (Cetacea: Odontoceti) from the early Miocene Astoria Formation and a revision of the stem delphinidan family Kentriodontidae" . Journal of Vertebrate Paleontology. 38 (2) e1411357. Bibcode:2018JVPal..38E1357P. doi:10.1080/02724634.2017.1411357. ISSN 0272-4634. S2CID 89965454.
1 2 Coombs, Margery Chalifoux (1979). "Tylocephalonyx, a new genus of North American dome-skulled chalicotheres (Mammalia, Perissodactyla)". Bulletin of the AMNH. 164 (1): 1–64. hdl:2246/1041.
1 2 Mayr, Gerald; Goedert, James L. (July 2017). "Oligocene and Miocene albatross fossils from Washington State (USA) and the evolutionary history of North Pacific Diomedeidae". The Auk. 134 (3): 659–671. doi: 10.1642/AUK-17-32.1 . ISSN 0004-8038. S2CID 89636332.
1 2 3 4 5 6 7 8 9 10 11 Welton, Bruce J. (October 1972). "Fossil Sharks in Oregon" (PDF). The Ore Bin. 34 (10): 161–172.
1 2 Welton, Bruce J. (2015-08-21). "A New Species of Late Early Miocene Cetorhinus (Lamniformes; Cetorhinidae) from the Astoria Formation of Oregon, and coeval Cetorhinus from Washington and California". Contributions in Science. 523: 67––89. doi: 10.5962/p.241294 . ISSN 0459-8113. S2CID 242792009.

Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database" . Retrieved 17 December 2021.
Moore, E. (1963). "Miocene marine mollusks from the Astoria formation in Oregon". Professional Paper. doi: 10.3133/PP419 . S2CID 127613845.{{cite book}}: Missing or empty |title= (help)
"Stratigraphy and sedimentation of the Onion Peak area, Clatsop County, Oregon". 1974.{{cite journal}}: Cite journal requires |journal= (help)

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[:4-1] 1 2 3 "Geolex — Astoria publications". ngmdb.usgs.gov. Retrieved 2022-12-19.

[:1-2] 1 2 3 4 5 Toshiyuki, Kimura; Barnes, Lawrence G. (March 2016). "New Miocene fossil Allodelphinidae (Cetacea, Odontoceti, Platanistoidea) from the North Pacific Ocean". Bull.Gunma Mus.Natu.Hist. 20: 1–58.

[:3-3] 1 2 3 4 Barnes, Lawrence G. (1987-06-18). "An Early Miocene pinniped of the genus Desmatophoca (Mammalia: Otariidae) from Washington". Contributions in Science. 382: 1–20. doi: 10.5962/p.208126 . ISSN 0459-8113. S2CID 198245103.

[:11-4] 1 2 3 4 5 Ray, Clayton E. (1976). "Fossil Marine Mammals of Oregon". Systematic Zoology. 25 (4): 420–436. doi:10.2307/2412515. ISSN 0039-7989. JSTOR 2412515.

[:14-5] 1 2 Berta, Annalisa (1991). "New Enaliarctos* (Pinnipedimorpha) from the Oligocene and Miocene of Oregon and the Role of "Enaliarctids" in Pinniped Phylogeny". Smithsonian Contributions to Paleobiology. 69 (69): 1–33. doi:10.5479/si.00810266.69.1. hdl:10088/19145.

[:7-6] 1 2 Poust, Ashley; Boessenecker, Robert (2018). "Expanding the geographic and geochronologic range of early pinnipeds: new specimens of Enaliarctos from Northern California and Oregon". Acta Palaeontologica Polonica. 63. doi: 10.4202/app.00399.2017 . S2CID 55978096.

[:0-7] 1 2 Tate-Jones, M. Kellum; Peredo, Carlos M.; Marshall, Christopher D.; Hopkins, Samantha S. B. (2020-07-03). "The Dawn of Desmatophocidae: A New Species of Basal Desmatophocid Seal (Mammalia, Carnivora) from the Miocene of Oregon, U.S.A." . Journal of Vertebrate Paleontology. 40 (4) e1789867. Bibcode:2020JVPal..40E9867T. doi:10.1080/02724634.2020.1789867. ISSN 0272-4634. S2CID 224935328.

[:12-8] 1 2 Barnes, Lawrence G. (1992-04-07). "A new genus and species of Middle Miocene enaliarctine pinniped (Mammalia, Carnivora, Otariidae) from the Astoria Formation in coastal Oregon". Contributions in Science. 431: 1–27. doi: 10.5962/p.208159 . ISSN 0459-8113. S2CID 199822990.

[:6-9] 1 2 Deméré, Thomas A.; Berta, Annalisa (2001-07-20). "A reevaluation of Proneotherium repenningi from the Miocene Astoria Formation of Oregon and its position as a basal odobenid (Pinnipedia: Mammalia)". Journal of Vertebrate Paleontology. 21 (2): 279–310. doi:10.1671/0272-4634(2001)021[0279:AROPRF]2.0.CO;2. ISSN 0272-4634. S2CID 88095414.

[:8-10] 1 2 Berta, Annalisa (1994). New specimens of the Pinnipediform Pteronarctos from the Miocene of Oregon. Washington, D.C: Smithsonian Institution Press.

[:5-11] 1 2 Boersma, Alexandra T.; McCurry, Matthew R.; Pyenson, Nicholas D. (May 2017). "A new fossil dolphin Dilophodelphis fordycei provides insight into the evolution of supraorbital crests in Platanistoidea (Mammalia, Cetacea)". Royal Society Open Science. 4 (5) 170022. Bibcode:2017RSOS....470022B. doi:10.1098/rsos.170022. ISSN 2054-5703. PMC 5451807 . PMID 28573006.

[12] Peredo, Carlos Mauricio; Uhen, Mark D.; Nelson, Margot D. (2018-03-04). "A new kentriodontid (Cetacea: Odontoceti) from the early Miocene Astoria Formation and a revision of the stem delphinidan family Kentriodontidae" . Journal of Vertebrate Paleontology. 38 (2) e1411357. Bibcode:2018JVPal..38E1357P. doi:10.1080/02724634.2017.1411357. ISSN 0272-4634. S2CID 89965454.

[:13-13] 1 2 Coombs, Margery Chalifoux (1979). "Tylocephalonyx, a new genus of North American dome-skulled chalicotheres (Mammalia, Perissodactyla)". Bulletin of the AMNH. 164 (1): 1–64. hdl:2246/1041.

[:2-14] 1 2 Mayr, Gerald; Goedert, James L. (July 2017). "Oligocene and Miocene albatross fossils from Washington State (USA) and the evolutionary history of North Pacific Diomedeidae". The Auk. 134 (3): 659–671. doi: 10.1642/AUK-17-32.1 . ISSN 0004-8038. S2CID 89636332.

[:10-15] 1 2 3 4 5 6 7 8 9 10 11 Welton, Bruce J. (October 1972). "Fossil Sharks in Oregon" (PDF). The Ore Bin. 34 (10): 161–172.

[:9-16] 1 2 Welton, Bruce J. (2015-08-21). "A New Species of Late Early Miocene Cetorhinus (Lamniformes; Cetorhinidae) from the Astoria Formation of Oregon, and coeval Cetorhinus from Washington and California". Contributions in Science. 523: 67––89. doi: 10.5962/p.241294 . ISSN 0459-8113. S2CID 242792009.

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