Dry Gulch Creek Member (SDSNH Locality 5939)
Basic information
Sample name: Dry Gulch Creek Member (SDSNH Locality 5939)
Reference: T. S. Kelly, P. C. Murphey, and S. L. Walsh. 2012. New records of small mammals from the Middle Eocene Duchesne River Formation, Utah, and their implications for the Uintan-Duchesnean North American Land Mammal Age transition. Paludicola 8(4):208-251 [ER 4154]
Geography
Country: United States
State: Utah
County: Uintah
Coordinate: 40.36° N, -109.71° W
Coordinate basis: estimated from map
Formation: Duchesne River
Time interval: Middle Eocene
Zone: Duchesnean
Section: Uinta
Unit number: 7
Unit order: below to above
Max Ma: 41.03
Min Ma: 40.26
Age basis: other
Geography comments: there are no locality data whatsoever, but I assume the sample is from somewhere in Halfway Hollow, which is shown in Fig. 1 as centered in the eastern part of T 5 S, R 19 E (coordinate estimated from the map)
from the Dry Gulch Creek Member of the Duchesne River Formation, equivalent to the "upper three-quarters of the Halfway horizon" of Kay (1934)
"The Lapoint Ash... overlies the Dry Gulch Creek Member localities" and there are "six 40Ar/39Ar dates... with a mean age of... 40.26 ± 0.08 Ma" on it
the mean date does fall within chron C18r based also on Ogg (2020)
although there are no paleomagnetic data at this level, rocks assigned to C18r underlie the sample (Fig. 14)
therefore, the maximum age is the base of C18r (Ogg 2020) and the minimum is the Lapoint date
from the Dry Gulch Creek Member of the Duchesne River Formation, equivalent to the "upper three-quarters of the Halfway horizon" of Kay (1934)
"The Lapoint Ash... overlies the Dry Gulch Creek Member localities" and there are "six 40Ar/39Ar dates... with a mean age of... 40.26 ± 0.08 Ma" on it
the mean date does fall within chron C18r based also on Ogg (2020)
although there are no paleomagnetic data at this level, rocks assigned to C18r underlie the sample (Fig. 14)
therefore, the maximum age is the base of C18r (Ogg 2020) and the minimum is the Lapoint date
Environment
Lithology: siltstone
Habitat comments: "a 10 cm thick reddish-brown muddy siltstone"
Methods
Life forms: rodents,other small mammals
Sampling methods: screenwash
Sample size: 63 specimens
Museum: SDSNH
Sampling comments: "a field investigation was initiated in 2006. Field methods include intensive surface prospecting and systematic blind collection of bulk matrix samples... Field work... took place intermittently between 2006 and 2009" and "A bulk sample consisting of 218 kg... was collected from SDSNH Locality 5939 because the test sample yielded the largest initial sample of identifiable mammal teeth. An additional 227 kg was collected from the locality in December, 2006" (the test sample weighed 9 kg, so the total is 454 kg)
"All matrix samples were sieved"
it is not clear whether any of the reported microfossils were obtained by surface collecting
eight additional specimens of indeterminate myomorphs are also noted
"All matrix samples were sieved"
it is not clear whether any of the reported microfossils were obtained by surface collecting
eight additional specimens of indeterminate myomorphs are also noted
Metadata
Sample number: 4613
Contributor: John Alroy
Enterer: John Alroy
Created: 2024-12-14 17:16:11
Modified: 2024-12-14 17:16:11
Abundance distribution
16 species
5 singletons
total count 63
geometric series index: 35.3
Fisher's α: 6.916
geometric series k: 0.8312
Hurlbert's PIE: 0.8589
Shannon's H: 2.2998
Good's u: 0.9236
Each square represents a species. Square sizes are proportional to counts.
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Register
| Copedelphys sp. | 2 | |
| Lipotyphla indet. | 2 | |
| Mytonolagus sp. | 1 | |
| †Pareumys guensburgi | 2 | |
| Griphomys sp. | 3 | |
| Passaliscomys sp. | 1 | |
| Heliscomys sp. | 2 | |
| †Metanoiamys lacus | 16 | |
| †Metanoiamys cf. korthi | 11 | |
| †Protadjidaumo typus | 10 | |
| †Protadjidaumo cf. typus | 6 | |
| large form, not the same species | ||
| Paradjidaumo sp. | 2 | |
| †Adjidaumo cf. craigi | 2 | |
| Simiacritomys sp. | 1 | |
| Microeutypomys sp. | 1 | |
| Eutypomys sp. | 1 | |