Correlation of the Fish Lake Valley and Cedar Mountain Beds in the Esmeralda Formation of Nevada

Stirton, R. A.

doi:10.1126/science.76.1959.60

Cited by 5 publications

(4 citation statements)

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“…The locomotory ecology of additional anchitheriomyines will have to be analysed to confirm the hypothesis laid out herein. However, already, Anchitheriomys tungurensis from the middle Miocene of China has been suggested to be semi-aquatic [11,72]. If all anchitheriomyines were semi-aquatic and the relatively poorly known fossil beaver Agnotocastor is indeed a junior synonym of Propalaeocastor, the oldest anchitheriomyine in the world would be P. galushai from the early Oligocene of North America [73].…”

Section: Discussionmentioning

confidence: 99%

The oldest semi-aquatic beaver in the world and a new hypothesis for the evolution of locomotion in Castoridae

Calede

2022

R. Soc. open sci.

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The North American rodent fossil record includes hundreds of species representing both an incredible taxonomic diversity and great ecological disparity. Although it is during the Oligocene that taxonomic diversity first peaks, it is not until the Miocene, almost 10 Myr later, that many ecologies, particularly locomotory ecologies, are recorded. Here, I present a new Oligocene-aged species of beaver from Montana, Microtheriomys articulaquaticus sp. nov., which represents the oldest semi-aquatic rodent in North America and the oldest amphibious beaver in the world, pushing the advent of semi-aquatic ecology in beavers by 7 Myr. I also provide morphological data supporting a terrestrial ecology for the sister taxon to Castoridae. Together with existing data, these findings lead to a new hypothesis for the evolutionary ecology of castorids whereby swimming was exapted from burrowing during the Oligocene. This evolution of semi-aquatic locomotion may have taken place in North America instead of Eurasia. It started in small beavers with gigantism achieved only much later. Indeed, body size evolution in castoroids follows a directional drift. Beavers obey Cope's rule, a selection for larger size over time that appears associated with semi-aquatic ecology and may well explain their low modern diversity.

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Section: Discussionmentioning

confidence: 99%

The oldest semi-aquatic beaver in the world and a new hypothesis for the evolution of locomotion in Castoridae

Calede

2022

R. Soc. open sci.

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“…Hance also noted the rather high amount of folding and faulting in these beds, making measurement of true stratigraphic thickness difficult. On the basis of mammalian fossils, Stirton (1932) During World War II, the U.S. Geological Survey and the U.S.…”

Section: Methods Used In the Investigationmentioning

confidence: 99%

Geology of a part of the southern Monte Cristo Range, Esmeralda County, Nevada

Moore¹

1981

Open-File Report

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“…Stirton (1936) described the vertebrate fauna of the Esmeralda Formation and Knowlton (1900), Berry (1927), and Axelrod (1940) have described the flora. More recent investigations include reconnaissance mapping of the Hawthorne and Tonopah quadrangles to the north (Ferguson and Muller, 1949), the Coaldale quadrangle (Ferguson and others, 1953), and Esmeralda County (Albers and Stewart, 1965).…”

Section: Previous Workmentioning

confidence: 97%

“…The Esmeralda Formation in the northern part of Fish Lake Valley has long been famous for its well preserved and varied vertebrate fauna (Stirton, 1932(Stirton, , 1936. These rocks are predominantly tuffaceous sandstones and reworked tuffs with subordinate siltstones, pebble on June 26, 2015 memoirs.gsapubs.org Downloaded from conglomerates, and cherts.…”

Section: Fish Lake Valleymentioning

confidence: 99%

Cenozoic Volcanism and Sedimentation, Silver Peak Region, Western Nevada and Adjacent California

Robinson

McKee²,

Moiola³

1968

Geological Society of America Memoirs

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Cenozoic deposits of the Silver Peak region, western Nevada, and adjacent California consist principally of continental sedimentary and pyroclastic rocks of the Esmeralda Formation and lavas and tuffs of the Silver Peak volcanic center.The sedimentary rocks comprise several thick sequences of tuffaceous volcanic sandstone and siltstone and interbedded air-fall tuff. These rocks were deposited in basins that coincide in a general way with the present valleys. Thick wedges of conglomerate and sandstone occur along the basin margins and reflect source areas.Most of the sedimentary rocks were deposited under fluctuating fluviatile and lacustrine conditions, but paludal conditions prevailed locally. Abrupt facies changes and numerous local unconformities indicate that deposition was not uniform within a given basin.The sedimentary rocks range in age from late Miocene to late Pliocene. The oldest reliably dated rocks in the Esmeralda Formation are 13.1 m.y. 577 on June 26, 2015 memoirs.gsapubs.org Downloaded from 578 STUDIES IN VOLCANOLOGY by K-Ar (Barstovian), and all sedimentary strata are younger than an ashflow sheet dated at 21.5 m.y. by K-Ar. An air-fall tuff in the upper part of the section has a K-Ar age of 4.3 m.y.Rocks of the Silver Peak volcanic center, 4.8 to 6.1 m.y. by K-Ar, crop out principally in the central part of the Silver Peak Range. Along the margins of the range, they overlie and interfinger with the various sedimentary sequences. The volcanic rocks are mostly rhyolite and trachyandesite tuffs and flows with subordinate basalts and andesites.Basin and Range faulting began in late early to middle Miocene time and has continued intermittently to the present, but present topography was largely established by late Pliocene time. CONTENTS

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Correlation of the Fish Lake Valley and Cedar Mountain Beds in the Esmeralda Formation of Nevada

Cited by 5 publications

References 0 publications

The oldest semi-aquatic beaver in the world and a new hypothesis for the evolution of locomotion in Castoridae

The oldest semi-aquatic beaver in the world and a new hypothesis for the evolution of locomotion in Castoridae

Geology of a part of the southern Monte Cristo Range, Esmeralda County, Nevada

Cenozoic Volcanism and Sedimentation, Silver Peak Region, Western Nevada and Adjacent California

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