San Timoteo Formation

San Timoteo Formation
Type	Formation
Location
Region	California
Country	United States

The San Timoteo Formation, also called the San Timoteo Beds, is a geologic formation in California.

History

Part of the wider San Timoteo Badlands, San Timoteo Formation was initially excavated in San Timoteo Canyon under by a team sponsored by Childs Frick from 1916 to 1921.^[1][2]

Geology

The San Timoteo Formation represents Pliocene and Early Pleistocene sediments, mostly sandstone. The Formation overlies the late Miocene and early Pliocene Mt. Eden Formation (Jack Rabbit Trail & Eden Hot Springs localities, corresponding to the Hemphillian and Blancan faunal stages).^[2]

Fossils

Fossils of Irvingtonian prehistoric mammals were found in the San Timoteo Formation (El Casco, Mammoth and Shutt Ranch localities).^[2][3][4][5] These include:

• Canis edwardii (Edward's wolf)
• Microtus sp. (vole)
• Ondatra idahoensis (muskrat)
• Mictomys kansasensis (bog lemming)
• Erethizon cascoensis (porcupine)
• “Plesippus” fracescana (three-toed horse)
• Equus bautistensis (horse)
• Tapirus merriami (tapir)
• Odocoileus cascaensis (deer)
• Megalonyx sp. (ground sloth)
• Mammuthus sp. (mammoth)
• Possibly a giant bear (may be either Arctodus or Agriotherium)^[6]

Fossils have also been recovered from the El Casco Substation locality, which was dated to 1.4Mya. Recovered specimens include Smilodon gracilis, Homotherium, two ground sloths, two types of camels, a llama, horse, and deer. Plant fossils include birch, pine, sycamore and oak trees.^[7][8][9]

See also

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

References

1. "The Bone Mine". The Banning Record. 1918-03-07. p. 2. Retrieved 2023-11-17.
2. Albright, L. Barry; Kendall, Jr., Arthur (2000-08-03). Biostratigraphy and Vertebrate Paleontology of the San Timoteo Badlands, Southern California. University of California Press. doi:10.1525/california/9780520098367.003.0001. ISBN 978-0-520-09836-7.
3. "San Timoteo Badlands". www.utep.edu. Retrieved 2024-07-22.
4. "Big Pine Citizen 2 March 1918 — California Digital Newspaper Collection". cdnc.ucr.edu. Retrieved 2023-11-17.
5. McComas, Katie (8 May 2019). "Paleontological Records Search – Gilman Springs Median and Shoulder Widening Project" (PDF) – via San Diego Natural History Museum.
6. Scott, Eric; Cox, Shelley M. (May 24, 1993). "Arctodus simus (Cope, 1879) from Riverside County, California" (PDF). PaleoBios. 15 (2): 27–36.
7. "The Associated Press: Calif. utility stumbles on 1.4M-year-old fossils". 2010-09-24. Archived from the original on 2010-09-24. Retrieved 2024-07-23.
8. "El Casco Substation". LSA. Retrieved 2024-07-23.
9. "Southern California Edison Discovers Most Comprehensive Collection of Fossils of its Era in Southern California". Edison International | Newsroom. Retrieved 2024-07-23.

• Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.