نتایج جستجو برای: trace fossils

تعداد نتایج: 80653  

Journal: :Proceedings. Biological sciences 2012
Nicholas J Minter M Gabriela Mángano Jean-Bernard Caron

The first arthropod trackways are described from the Middle Cambrian Burgess Shale Formation of Canada. Trace fossils, including trackways, provide a rich source of biological and ecological information, including direct evidence of behaviour not commonly available from body fossils alone. The discovery of large arthropod trackways is unique for Burgess Shale-type deposits. Trackway dimensions ...

2007
Richard J. Twitchett

Early Triassic animal body fossils and trace fossils are small relative to those in older and younger intervals. Size decreases sharply through the end-Permian extinction event and Permian/Triassic boundary, and the smallest sizes are encountered in the parvus and isarcica Zones of the earliest Induan. Animals appearing within these two zones are also exceedingly small, compared to younger cong...

Journal: :Fossil Imprint 2021

Upper Ordovician shallow marine fine-grained sandstones and siltstones exposed in the Loděnice – vinice locality yielded a distinct well-preserved tiering pattern of trace fossils. The two uppermost tiers are composed mainly Bifungites Nereites. Deeper sediment, dominated by Thalassinoides, Zoophycos Teichichnus occur. Most succession is completely bioturbated; however, several storm layers ena...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2009
Thomas F Bristow Martin J Kennedy Arkadiusz Derkowski Mary L Droser Ganqing Jiang Robert A Creaser

Assemblages of clay minerals are routinely used as proxies for paleoclimatic change and paleoenvironmental conditions in Phanerozoic rocks. However, this tool is rarely applied in older sedimentary units. In this paper, the clay mineralogy of the Doushantuo Formation in South China is documented, providing constraints on depositional conditions of the Ediacaran Yangtze platform that host the ea...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Jacob R Waldbauer Dianne K Newman Roger E Summons

The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth's evolution. Among the various geochemical proxies for the presence of O(2) in the environment, molecular fossils offer a unique record of O(2) where it was f...

2003
Geoff S. Humphreys

INTRODUCTION The important role of fauna in modifying the regolith by redistributing particles is now widely acknowledged (e.g., Paton et al. 1995). One issue of some importance to regolith studies and the interpretation of paleosols is how the role of terrestrial bioturbation has evolved since life first invaded the land areas of Earth in the Early Paleozoic. This particular issue was raised d...

2005
SPENCER G. LUCAS ANDREW B. HECKERT LAWRENCE H. TANNER

Most fossil vertebrates of Jurassic age from Arizona are derived from the Glen Canyon Group on the southern Colorado Plateau in the northeastern part of the state. Glen Canyon Group strata of Jurassic age in Arizona that yield fossils include the upper Dinosaur Canyon and the Whitmore Point members of the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. All of these units yie...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2015
Sarah E Moffitt Tessa M Hill Peter D Roopnarine James P Kennett

Anthropogenic climate change is predicted to decrease oceanic oxygen (O2) concentrations, with potentially significant effects on marine ecosystems. Geologically recent episodes of abrupt climatic warming provide opportunities to assess the effects of changing oxygenation on marine communities. Thus far, this knowledge has been largely restricted to investigations using Foraminifera, with littl...

2016
ROBERT A. GASTALDO

The Trout Valley Formation of Emsian–Eifelian age in northern Maine hosts evidence of early vascular plant communities interpreted as having colonized wetland, estuarine environments. To date, collections made under permits issued by the Baxter State Park Commission, originate from outcrop along Trout Brook, its tributaries, and poorly exposed lithologies inside the woodlands. Construction of a...

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