UCMP V-3611, Mulholland Site 2 (Neogene of the United States)

Where: Contra Costa County, California (37.9° N, 122.1° W: paleocoordinates 37.4° N, 119.6° W)

• coordinate based on political unit

• small collection-level geographic resolution

When: Garrity Formation, Hemphillian (10.3 - 4.9 Ma)

• referred to the Orinda Fm. by Stirton but to the Mulholland Fm. by Creely et al. 1982; not directly superposed above the Orinda/Moraga/Siesta sites contra Tedford et al. 1987, but a lateral equivalent of the Bald Peak Basalt, which overlies the Siesta Fm. (Creely et al. 1982) and is dated at 7.7 (=7.91) Ma (KA on olivine: Evernden et al. 1964) superposed above the undifferentiated Contra Costa Group, including Bolinger Canyon and other "Orinda" sites of Stirton.
As discussed in Martin et al. 2023, revised stratigraphy of area by Wagner et al. 2021 places locality in the Garrity Formation, which overlies the Mulholland members of the Siesta Formation and is stratigraphically above the UCMP V3611 occurs above the

•Crow Canyon (8.2 Ma, Ar/Ar) and Bolinger Canyon (8.1 Ma Ar/Ar) and below the San Pablo Dam Tuff (7.8 Ma Ar/Ar).

Environment/lithology: terrestrial; lithology not reported

Size class: macrofossils

Reposited in the UCMP

Primary reference: R. A. Stirton. 1939. Cenozoic Mammal Remains From the San Francisco Bay Region. University of California Publications, Bulletin of the Department of Geological Sciences 24(13):339-410 [J. Alroy/J. Alroy/J. Marcot]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 19447: authorized by John Alroy, entered by John Alroy on 26.03.1995, edited by Patricia Holroyd

Creative Commons license: CC BY (attribution)

Taxonomic list

Gastropoda
 Heterostropha - Lymnaeidae
Lymnaea sp.2 Lamarck 1799 snail
"compare L. kerri"
 Stylommatophora - Agriolimacidae
Bivalvia
 Cardiida - Sphaeriidae
Sphaerium cynodon2 fingernail clam
abundant; listed under equivalent site number UCMP B7270
 Unionida - Unionidae
Anodonta nuttalliana2 freshwater mussel
subsp. lignitica; rare; listed under equivalent site number UCMP B7270
Mammalia
 Rodentia - Castoridae
Dipoides sp.1 Jaeger 1835 beaver
confirmed as coming from this site by JA during visit to UCMP
 Rodentia - Cricetidae
Peromyscus sp.3 Gloger 1841 deer mouse
closely compares to Recent species
Pliotomodon primitivus n. sp.3 Hoffmeister 1945 mouse
see also Jacobs and Lindsay 1984
 Lagomorpha - Leporidae
Hypolagus tedfordi4 White 1988 rabbit
 Perissodactyla - Rhinocerotidae
Teleoceras sp. Hatcher 1894 rhinoceros
probably "T cf. fossiger" from the Mulholland Fm. of Creely et al. 1982
 Perissodactyla - Equidae
Hipparionini indet., "Pliohippus spectans" = Dinohippus spectans
Hipparionini indet. Quinn 1955 hipparionine horse
"Nannippus" - not clear what this is, specimen is an undiagnostic m3: JA pers. obs. 11.12.94
"Pliohippus spectans" = Dinohippus spectans Cope 1880 horse
 Artiodactyla - Camelidae
Camelidae indet. Gray 1821 camel
 Carnivora - Canidae
Canidae indet. Fischer de Waldheim 1817 canid
 Megatherioidea - Megalonychidae
Megalonychidae indet. Gervais 1855 edentate
mentioned by Hoffmeister 1945; Hirschfeld and Webb 1968; Marshall et al. 1979; Hirschfeld 1981