PBDB Collection

Spring Canyon (Eocene of the United States)

Also known as SDSNH 4041, 4042; Upper Pomerado Conglomerate

Where: San Diego County, California (32.9° N, 117.0° W)

• Paleocoordinates: 37.4° N, 98.4° W (Wright 2013)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Pomerado Formation, Duchesnean (39.7 - 37.0 Ma)

• said to be late Duchesnean to early Chadronian "about 10 m above the base of the upper member" (Walsh 2010); age refined in Poust et al. to middle to late Duchesnean based on interpretation of upper part of Pomerado Conglomerate as falling within Chron 17n

• bed-level stratigraphic resolution

Environment/lithology: terrestrial; gray, green, silty mudstone

• "Locality 4041 consists of a single large rip-up clast of purplish and greenish mudstone occurring within a pale gray cobble conglomerate... almost certaintly derived from an immediately underlying, laterally extensive bed of pale greenish gray siltstone and mudstone up to 1 m thick, from which Locality 4042 was collected" (Walsh 2010)

Size class: mesofossils

Collection methods: bulk, chemical, sieve

• SDSNH collection

•"Approximately 360 kg of matrix from [4041] and ~3800 kg of matrix from [4042] were screenwashed using 30-mesh screens (0.6 mm square openings)... concentrates were processed... using the heavy liquid tetrabromoethane"

Primary reference: A. W. Poust, P. Z. Barrett, and S. Tomiya. 2022. An early nimravid from California and the rise of hypercarnivorous mammals after the middle Eocene climatic optimum. Biology Letters 18(20220291):1-6 [P. Holroyd/P. Holroyd]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 17039: authorized by John Alroy, entered by John Alroy on 21.09.1999, edited by Patricia Holroyd

Creative Commons license: CC0 (CC0)

Taxonomic list

Show authors, comments, and common names

Mammalia
Tribosphenida - Herpetotheriidae	Herpetotherium valens² Herpetotherium valens² Lambe 1908 marsupial
Tribosphenida - Peradectidae	Peradectes sp.² Peradectes sp.² Matthew and Granger 1921 marsupial
Rodentia - Eomyidae	cf. Metanoiamys sp.², Protadjidaumo sp.², cf. Paradjidaumo sp.² cf. Metanoiamys sp.² Chiment and Korth 1996 rodent Protadjidaumo sp.² Burke 1934 rodent cf. Paradjidaumo sp.² Burke 1934 rodent
Rodentia -	cf. Griphomys sp.² cf. Griphomys sp.² Wilson 1940 rodent said to be new
Rodentia - Heliscomyidae	Heliscomys sp.² Heliscomys sp.² Cope 1873 rodent
Rodentia -	Nonomyinae indet.¹, Nonomys gutzleri n. sp.¹ Nonomyinae indet.¹ Martin 1980 rodent said to be new Nonomys gutzleri n. sp.¹ Walsh 2010 rodent said to be new
Rodentia - Ischyromyidae	Ischyromys sp.² Ischyromys sp.² Leidy 1856 rodent
Primates - Microsyopidae	Uintasoricinae indet.² Uintasoricinae indet.² Szalay 1969 primate
Soricomorpha - Geolabididae	Centetodon cf. magnus² Centetodon cf. magnus² Clark 1936 placental
Carnivora - Nimravidae	Pangurban egiae n. gen. n. sp. Pangurban egiae n. gen. n. sp. Poust et al. 2022 false sabre-tooth
Carnivora - Mustelidae	Mustelidae indet.² Mustelidae indet.² Fischer 1817 mustelid carnivore
Perissodactyla - Equidae	Mesohippus sp.² Mesohippus sp.² Marsh 1875 anchitheriine horse
Artiodactyla - Agriochoeridae	? Agriochoeridae indet.² ? Agriochoeridae indet.² Leidy 1869 agriochoerid
Artiodactyla - Hypertragulidae	cf. Hypertragulus sp.² cf. Hypertragulus sp.² Cope 1874 ruminant
Artiodactyla - Camelidae	Camelidae indet.² Camelidae indet.² Gray 1821 camel

¹Walsh 2010; ²Walsh and Gutzler 1999