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Testate Amoebae in the Neoproterozoic Era: Evidence from Vase-shaped Microfossils in the Chuar Group, Grand Canyon
(Paleontological Society, 2000)
Vase-shaped microfossils (VSMs) occur globally in Neoproterozoic rocks, but until now their biological relationships have remained problematic. Exceptionally preserved new populations from the uppermost Chuar Group, Grand ...
Vase-shaped Microfossils from the Neoproterozoic Chuar Group, Grand Canyon: A Classification Guided by Modern Testate Amoebae
(Society of Economic Paleontologists and Mineralogists, 2003)
Vase-shaped microfossil (VSM) assemblages front early diagenetic carbonate nodules in >742 +/- 6 Ma black shales of the Chuar Group, Grand Canyon, provide evidence for affinities with testate amoebae. Not only are VSMs ...
Directionality in the History of Life: Diffusion from the Left Wall or Repeated Scaling of the Right?
(Elsevier, 2000)
Issues of directionality in the history of life can be framed in terms of six major evolutionary steps, or megatrajectories (cf. Maynard Smith and Szathmary 1995): (1) evolution from the origin of life to the last common ...
Secular Change in the Precambrian Silica Cycle: Insights from Chert Petrology
(Geological Society of America, 2005)
Chert deposits preserve a record of secular change in the oceanic silica cycle. The evolutionary radiation of silica-secreting organisms resulted in a transition from abiological silica deposition, characteristic of the ...
Eukaryotic Organisms in Proterozoic Oceans
(Royal Society, The, 2006)
The geological record of protists begins well before the Ediacaran and Cambrian diversification of animals, but the antiquity of that history, its reliability as a chronicle of evolution and the causal inferences that can ...
Phylogenetic Investigation of the Aliphatic, Non-hydrolyzable Biopolymer Algaenan, with a Focus on Green Algae
(Elsevier, 2009)
Algaenan, an aliphatic biopolymer found in various microalgae, has been implicated as the source of a sizable proportion of the aliphatic refractory organic matter in sedimentary rocks. Because of its recalcitrant nature, ...
Macroscopic Carbonaceous Compressions in a Terminal Proterozoic Shale: A Systematic Reassessment of the Miaohe Biota, South China
(Society of Economic Paleontologists and Mineralogists, 2002)
Carbonaccous compression fossils in shales of the uppermost Doushantuo Formation (ca. 555-590 Ma) at Miaohe in the Yangtze Gorges area provide a rare Burgess-Shale-type taphonomic window on terminal Proterozoic biology. ...
Sedimentary Controls on the Formation and Preservation of Microbial Mats in Siliciclastic Deposits: A Case Study from the Upper Neoproterozoic Nama Group, Namibia
(Society of Economic Paleontologists and Mineralogists, 2002)
Shallow-marine, siliciclastic depositional systems are dominated by physical sedimentary processes, with penecontemporaneous cementation playing only a minor role in sediment dynamics. For this reason, microbial mats rarely ...
Molar Tooth Structures in Calcareous Nodules, Early Neoproterozoic Burovaya Formation, Turukhansk Region, Siberia
(Elsevier, 2003)
Molar tooth structures are abundant in large (1-2 m diameter) carbonate nodules within fine-grained, subtidal carbonates of the early Neoproterozoic (lower Upper Riphean) Burovaya Formation along the Sukhaya Tunguska River, ...
An Astrobiological Perspective on Meridiani Planum
(Elsevier, 2005)
Sedimentary rocks exposed in the Meridiani Planum region of Mars record aqueous and eolian deposition in ancient dune and interdune playa-like environments that were arid, acidic, and oxidizing. On Earth, microbial populations ...