Alsea Formation

Alsea Formation
Stratigraphic range: Rupelian (Whitneyan) ~33.7–30.6 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Formation
Underlies	Yaquina Formation
Lithology
Primary	Siltstone
Other	Mudstone
Location
Coordinates	44°36′N 124°00′W / 44.6°N 124.0°W / 44.6; -124.0
Approximate paleocoordinates	44°18′N 113°06′W / 44.3°N 113.1°W / 44.3; -113.1
Region	Lincoln County, Oregon
Country	United States
Alsea Formation (the United States) Show map of the United States Alsea Formation (Oregon) Show map of Oregon

The Alsea Formation is a geologic formation in Oregon. It preserves fossils dating back to the Rupelian stage of the Oligocene period.^[1]

Fossil content[edit]

The following fossils have been reported from the formation:^[1]

Mammals[edit]

• Aetiocetus cotylalveus^[2]
• Maiabalaena nesbittae^[3]
• Simocetus rayi^[4]

Fish[edit]

• Orthechinorhinus davidae^[5]

See also[edit]

• List of fossiliferous stratigraphic units in Oregon
• Paleontology in Oregon

References[edit]

Bibliography[edit]

• Peredo, C. M.; N. D. Pyenson; C. D. Marshall, and M. D. Uhen. 2018. Tooth loss precedes the origin of baleen in whales. Current Biology 28. 1-9. .
• Welton, B. J. 2016. First report of Orthechinorhinus (Squaliformes: Etmopteriidae) from the Pacific Basin; A new species from Early Oligocene rocks of Oregon, USA. Fossil Record 5. 303–308. .
• Deméré, T. A., and A. Berta. 2008. Skull anatomy of the Oligocene toothed mysticete Aetiocetus weltoni (Mammalia; Cetacea): implications for mysticete evolution and functional anatomy. Zoological Journal of the Linnean Society 154. 308–352. .
• Fordyce, R. E. 2002. Simocetus rayi (Odontoceti, Simocetidae, new family); a bizarre new archaic Oligocene dolphin from the eastern North Pacific. Smithsonian Contributions to Paleobiology 93. 185–222. .