Santiago Formation, California

Santiago Formation
Santiago Formation
Stratigraphic range: Late Eocene-Late Oligocene (Uintan-Duchesnean)
Type	Geological formation
Lithology
Primary	Siltstone, mudstone
Other	Sandstone
Location
Coordinates	33°06′N 117°18′W / 33.1°N 117.3°W
Approximate paleocoordinates	33°18′N 104°06′W / 33.3°N 104.1°W
Region	Orange & NW San Diego County, California
Country	United States
	Santiago Formation, California (the United States) Santiago Formation, California (California)

The Santiago Formation is a geologic formation in Orange and northwestern San Diego County, California. The siltstones, mudstones and sandstones of the formation preserve fossils of Walshina esmaraldensis and Diegoaelurus vanvalkenburghae, dating back to the Late Eocene to Late Oligocene periods (Uintan to Duchesnean in the NALMA classification).^[1]

Depositional environment

The only paleoenvironmental interpretation based exclusively on specimens from the Santiago Formation is a study of land snails from SDSNH locality 3276 (Member C, Oceanside, San Diego County), which found the distribution of shell sizes and shapes to be consistent with interpretations of subtropical to tropical conditions and paleotemperatures in excess of 25 °C (77 °F).^[2]

Fossil content

Mammals

Ferae

Ferae reported from the Santiago Formation
Genus	Species	Presence	Material	Notes	Images
Ceruttia	C. sandiegoensis	Member C.^[3]	Jaw elements & teeth.^[3]	A carnivoraform also found in the Mission Valley Formation.
Diegoaelurus	D. vanvalkenburghae	"Member C".^[4]	A nearly complete dentary.^[4]	An oxyaenid.
Lycophocyon	L. hutchisoni	Upper portions of "member C".^[5]	Multiple specimens.^[5]	A basal caniform.
Procynodictis	P. progressus	Member C.^[3]	Jaw elements & teeth.^[3]	A miacid also known from the Sespe & Mission Valley formations.

Primatomorphs

Primatomorphs reported from the Santiago Formation
Genus	Species	Presence	Material	Notes	Images
Chumashius	C. balchi	V-72088.^[6]	Isolated teeth.^[6]	An omomyid also known from the Sespe Formation.
Dyseolemur	D. pacificus	V-72088.^[6]	Isolated molars.^[6]	An omomyid also known from the Sespe Formation.
Walshina	W. esmaraldensis	Member C.^[7]	Teeth.^[7]	An omomyid also known from the Mission Valley & Sespe formations.

Ungulates

Ungulates reported from the Santiago Formation
Genus	Species	Presence	Material	Notes	Images
Hesperaletes	H. borineyi	Member C.^[8]	Numerous specimens.^[8]	A tapiroid.
Parvicornus	P. occidentalis	Member C.^[9]	Numerous specimens.^[9]	A brontothere.
Protoreodon	P. walshi	Member C.^[10]	Numerous specimens.^[10]	An oreodont.
Protoreodon	P. cf. walshi	Member C.^[10]	Jaw elements.^[10]	An oreodont.

Invertebrates

Invertebrates reported from the Santiago Formation
Genus	Species	Presence	Material	Notes	Images
Upogebia	U. aronae	Member B.^[11]	Numerous specimens.^[11]	A mud shrimp.

References

^ Kelly Ranch Core at Fossilworks.org
^ López Torres et al., 2018, p.5
^ ^a ^b ^c ^d Tomiya, Susumu (20 May 2013). "New carnivoraforms (Mammalia) from the middle Eocene of California, USA, and comments on the taxonomic status of 'Miacis' gracilis". Palaeontologia Electronica. 16 (2): 1–14. doi:10.26879/364. ISSN 1094-8074.
^ ^a ^b Zack, Shawn P.; Poust, Ashley W.; Wagner, Hugh (15 March 2022). "Diegoaelurus, a new machaeroidine (Oxyaenidae) from the Santiago Formation (late Uintan) of southern California and the relationships of Machaeroidinae, the oldest group of sabertooth mammals". PeerJ. 10: e13032. doi:10.7717/peerj.13032. ISSN 2167-8359. PMC 8932314. PMID 35310159. S2CID 247480756.
^ ^a ^b Tomiya, Susumu (14 September 2011). "A New Basal Caniform (Mammalia: Carnivora) from the Middle Eocene of North America and Remarks on the Phylogeny of Early Carnivorans". PLOS ONE. 6 (9): e24146. Bibcode:2011PLoSO...624146T. doi:10.1371/journal.pone.0024146. ISSN 1932-6203. PMC 3173397. PMID 21935380.
^ ^a ^b ^c ^d Lillegraven, Jason A. (1980). "Primates from Later Eocene Rocks of Southern California". Journal of Mammalogy. 61 (2): 181–204. doi:10.2307/1380040. ISSN 0022-2372. JSTOR 1380040.
^ ^a ^b López-Torres, Sergi; Silcox, Mary T.; Holroyd, Patricia A. (2018). "New omomyoids (Euprimates, Mammalia) from the late Uintan of southern California, USA, and the question of the extinction of the Paromomyidae (Plesiadapiformes, Primates)". Palaeontologia Electronica. 21 (3). doi:10.26879/756. ISSN 1094-8074.
^ ^a ^b Colbert, Matthew W. (11 September 2006). "Hesperaletes (Mammalia: Perissodactyla), a new tapiroid from the middle Eocene of southern California". Journal of Vertebrate Paleontology. 26 (3): 697–711. doi:10.1671/0272-4634(2006)26[697:HMPANT]2.0.CO;2. ISSN 0272-4634. S2CID 85719229.
^ ^a ^b Mihlbachler, Matthew C.; Deméré, T. A. (January 2009). "A new species of Brontotheriidae (Perissodactyla, Mammalia) from the Santiago Formation (Duchesnian, Middle Eocene) of Southern California". Proceedings of the San Diego Society of Natural History (41): 1–36.
^ ^a ^b ^c ^d Theodor, Jessica M. (1999). "Protoreodon walshi, a New Species of Agriochoerid (Oreodonta, Artiodactyla, Mammalia) from the Late Uintan of San Diego County, California". Journal of Paleontology. 73 (6): 1179–1190. Bibcode:1999JPal...73.1179T. doi:10.1017/S0022336000031061. ISSN 0022-3360. JSTOR 1306828. S2CID 133075207.
^ ^a ^b Haug, Carolin; Nyborg, Torrey; Vega, Francisco J. (2013). "An exceptionally preserved upogebiid (Decapoda: Reptantia) from the Eocene of California". Boletín de la Sociedad Geológica Mexicana. 65 (2): 235–248. doi:10.18268/BSGM2013v65n2a5. ISSN 1405-3322. JSTOR 24921220.

Bibliography

López Torres, S.; Silcox, M.T.; Holroyd, P.A. (2018), "New omomyoids (Euprimates, Mammalia) from the late Uintan of southern California, USA, and the question of the extinction of the Paromomyidae (Plesiadapiformes, Primates)", Palaeontologia Electronica, 21: 1–28, retrieved 15 March 2020