Mammalian Fauna of the Middle Eocene Kishenehn Formation, Middle Fork of the Flathead River, Montana

2018 ◽  
Vol 85 (1) ◽  
pp. 25-60 ◽  
Author(s):  
Mary R. Dawson ◽  
Kurt N. Constenius
Keyword(s):  
Middle Eocene ◽  
Mammalian Fauna ◽  
Middle Fork ◽  
Flathead River

scholarly journals Whence the beardogs? Reappraisal of the Middle to Late Eocene ‘ Miacis ’ from Texas, USA, and the origin of Amphicyonidae (Mammalia, Carnivora)

2016 ◽  
Vol 3 (10) ◽  
pp. 160518 ◽  
Author(s):  
Susumu Tomiya ◽  
Zhijie Jack Tseng
Keyword(s):  
North America ◽  
Great Plains ◽  
Geographical Origin ◽  
Middle Eocene ◽  
Cladistic Analysis ◽  
Rocky Mountain ◽  
Late Eocene ◽  
Northern Great Plains ◽  
Mammalian Fauna ◽  
Additional Support

The Middle to Late Eocene sediments of Texas have yielded a wealth of fossil material that offers a rare window on a diverse and highly endemic mammalian fauna from that time in the southern part of North America. These faunal data are particularly significant because the narrative of mammalian evolution in the Paleogene of North America has traditionally been dominated by taxa that are known from higher latitudes, primarily in the Rocky Mountain and northern Great Plains regions. Here we report on the affinities of two peculiar carnivoraforms from the Chambers Tuff of Trans-Pecos, Texas, that were first described 30 years ago as Miacis cognitus and M. australis . Re-examination of previously described specimens and their inclusion in a cladistic analysis revealed the two taxa to be diminutive basal amphicyonids; as such, they are assigned to new genera Gustafsonia and Angelarctocyon , respectively. These two taxa fill in some of the morphological gaps between the earliest-known amphicyonid genus, Daphoenus , and other Middle-Eocene carnivoraforms, and lend additional support for a basal caniform position of the beardogs outside the Canoidea. The amphicyonid lineage had evidently given rise to at least five rather distinct forms by the end of the Middle Eocene. Their precise geographical origin remains uncertain, but it is plausible that southern North America served as an important stage for a very early phase of amphicyonid radiation.

scholarly journals The first North American Propterodon (Hyaenodonta: Hyaenodontidae), a new species from the late Uintan of Utah

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8136 ◽  
Author(s):  
Shawn P. Zack
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
North American ◽  
Middle Eocene ◽  
North American Species ◽  
New Combination ◽  
Mammalian Fauna ◽  
Critical Interval ◽  
Uinta Basin ◽  
A New Species

The carnivorous mammalian fauna from the Uintan (late middle Eocene) of North America remains relatively poorly documented. This is unfortunate, as this is a critical interval in the transition from “creodont” to carnivoran dominated carnivore guilds. This study reports a new species from the Uinta Formation of the Uinta Basin, Utah, the first North American species of the otherwise Asian hyaenodont genus Propterodon. The new species, Propterodon witteri, represented by a dentary with M2-3 from the late Uintan Leota Quarry, is larger than the well-known P. morrisi and P. tongi and has a larger M3 talonid, but is otherwise very similar. A phylogenetic analysis of hyaenodont interrelationships recovers P. witteri as a hyaenodontine but is generally poorly resolved. A relationship between Hyaenodontinae and Oxyaenoides, recovered by many recent analyses, is not supported. Among the Asian species of Propterodon, P. pishigouensis is reidentified as a machaeroidine oxyaenid and recombined as Apataelurus pishigouensis new combination. Isphanatherium ferganensis may also represent an Asian machaeroidine. Identification of a North American species of Propterodon and an Asian Apataelurus increases the similarity of North American Uintan and Asian Irdinmanhan faunas and suggests that there was substantial exchange of carnivorous fauna during the late middle Eocene.

scholarly journals Fossil mammals from the central Chilean Andes: a new interval in the South American land mammal succession, and implications for Eocene-Oligocene boundary events and Andean tectonics

1992 ◽  
Vol 6 ◽  
pp. 318-318 ◽  
Author(s):  
A.R. Wyss ◽  
J.J. Flynn ◽  
C.C. Swisher ◽  
R. Charrier ◽  
M.A. Norell
Keyword(s):  
Late Cretaceous ◽  
Middle Eocene ◽  
South American ◽  
Mammalian Fauna ◽  
Late Mesozoic ◽  
The Andes ◽  
Early Tertiary ◽  
Tectonic Rotation ◽  
Land Mammal ◽  
Mammal Faunas

Biostratigraphically significant samples have been collected from six localities in post-Neocomian terrestrial deposits of the central Andean Main Range (34° 50 S latitude), Chile. Localities are distributed over an area of 13 km by 5 km, and span more than 2500 m of section.Two eastern localities occurring lowest in the sequence yield a diverse suite of more than 20 taxa indicative of a new biochronologic interval between the Mustersan (?middle Eocene) and Deseadan (?late Oligocene-early Miocene) South American Land Mammal Ages (LMA); speculatively it also is older than the enigmatic Divisideran “LMA”. Noteworthy occurrences include the first South American appearance of rodents, argyrolagoid marsupials, and interatheriine interathere and advanced notohippid Notoungulata, as well as the last appearance of polydolopid marsupials, and notopithicine and notostylopid Notoungulata. Four K-Ar and Ar40-Ar39 analyses on a flow and tuff which directly underlie one locality yield ages between 35.6 ± 0.9 and 37.56 ± 0.14 Ma; the fossiliferous unit itself has produced four Ar40-Ar39 dates between 31.7 ± 0.3 and 31.37 ± 0.08 Ma in one locality. Therefore, the new biochronologic interval appears to be earliest Oligocene in age, and is the oldest sequence representing Simpson's “Second Faunal Stratum”. The “Tinguiririca” assemblage is the oldest South American mammalian fauna dominated by herbivores (in a diversity of taxa) with high-crowned or evergrowing teeth, documenting major changes caused by interaction between a major phase of tectonic uplift in the central Andes and global climatic changes near the Eocene-Oligocene boundary.We recently recovered about one dozen skulls and jaws from several sites some 10 km west of, and 2500 m stratigraphically above, these lowest localities. The fauna from these new western sites appears advanced over the localities to the east, and probably is younger than about 20 Ma, based on stratigraphy and Ar40-Ar39 dates from units overlying the eastern localities. The new faunas should help resolve controversy concerning the younger limit of the Deseadan LMA.Discovery of the mammal faunas has profoundly altered understanding of central Andean geology: 1) we identified an unconformity between Jurassic marine/late Cretaceous clastic units and volcaniclastic mid-Tertiary deposits, indicating that a dramatic episode of volcanism previously attributed to the late Mesozoic is in fact 30 m.y. younger; 2) consequently, the late Cretaceous/early Tertiary is characterized by non-deposition or erosion, rather than by volcanic deposition as had been hypothesized earlier; and 3) our paleomagnetic results also indicate previously unrecognized, but significant post-Miocene clockwise tectonic rotation (up to 20°) of units in this part of the Andes.

Uintan land mammals (excluding rodents) from an estuarine facies of the Laredo Formation (Middle Eocene, Claiborne Group) of Webb County, Texas

1990 ◽  
Vol 64 (3) ◽  
pp. 454-468 ◽  
Author(s):  
James W. Westgate
Keyword(s):  
Coastal Plain ◽  
Rocky Mountains ◽  
Middle Eocene ◽  
Mammalian Fauna ◽  
East Texas ◽  
Gulf Coastal Plain ◽  
Local Fauna ◽  
West Texas ◽  
Mammal Fauna ◽  
Land Mammal

A newly discovered vertebrate fossil assemblage, the Casa Blanca local fauna, comes from the Laredo Formation, Claiborne Group, of Webb County, Texas, and is the first reported Eocene land-mammal fauna from the coastal plain of North America. The mammalian fauna is correlated with the Serendipity and Candelaria local faunas of west Texas, the Uinta C faunas of the Rocky Mountains, the Santiago Formation local fauna of southern California, and the Swift Current Creek local fauna of Saskatchewan. The vertebrate-bearing deposit lies approximately 32 m above a horizon containing the marine gastropod Turritella cortezi, which ranges from east Texas to northeast Mexico in the lower half of the Cook Mountain and Laredo Formations and is a guide fossil for the Hurricane Lentil in the Cook Mountain Formation. Nannoplankton found in these middle Eocene formations belong to the upper half of Nannoplankton Zone 16 and allow correlation with European beds of late Lutetian to early Bartonian age.Over 700 specimens represent at least 30 species of 28 mammal genera. The Casa Blanca fauna is the southernmost and easternmost North American land-mammal fauna of definite Eocene age, and is the westernmost Paleogene vertebrate fauna from the Gulf Coastal Plain.

Tracing dissolved O2 and dissolved inorganic carbon stable isotope dynamics in the Nyack aquifer: Middle Fork Flathead River, Montana, USA

2011 ◽  
Vol 75 (20) ◽  
pp. 5971-5986 ◽  
Author(s):  
M. Garrett Smith ◽  
Stephen R. Parker ◽  
Christopher H. Gammons ◽  
Simon R. Poulson ◽  
F. Richard Hauer
Keyword(s):  
Stable Isotope ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Stable Isotope ◽  
Middle Fork ◽  
Flathead River ◽  
Dissolved O2
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