A5016662094- Paleontology and Stratigraphy of Fossils
- Geology and Paleoclimatology Research
- Planetary Science and Exploration
- Astro and Planetary Science
- Hydrocarbon exploration and reservoir analysis
- Geological and Geochemical Analysis
- Geochemistry and Elemental Analysis
- Marine Biology and Ecology Research
- Methane Hydrates and Related Phenomena
- Protist diversity and phylogeny
- Space Science and Extraterrestrial Life
- Geological formations and processes
- Paleontology and Evolutionary Biology
- Geological Studies and Exploration
- Geochemistry and Geologic Mapping
- Geological and Geophysical Studies
- Evolution and Paleontology Studies
- Isotope Analysis in Ecology
- Space Exploration and Technology
- Plant Diversity and Evolution
- Marine and coastal plant biology
- Microbial Community Ecology and Physiology
- Diatoms and Algae Research
- Calcium Carbonate Crystallization and Inhibition
- Marine and coastal ecosystems
Harvard University
2016-2025
Harvard University Press
2007-2024
Planetary Science Institute
2013-2024
University of Akron
2022
Johns Hopkins University
2020
California Institute of Technology
2004-2020
University of Colorado System
2020
University of Colorado Boulder
2020
National Postdoctoral Association
2020
Bridge University
2020
Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering basaltic rocks, sulfate minerals (including magnesium and jarosite) that constitute several tens percent the rock by weight, hematite. Cross-stratification observed outcrops indicates eolian aqueous transport. Diagenetic features include hematite-rich concretions crystal-mold vugs. We interpret to be a mixture chemical sediments with complex diagenetic history....
Although macroscopic plants, animals, and fungi are the most familiar eukaryotes, bulk of eukaryotic diversity is microbial. Elucidating timing diversification among more than 70 lineages key to understanding evolution eukaryotes. Here, we use taxon-rich multigene data combined with diverse fossils a relaxed molecular clock framework estimate last common ancestor extant eukaryotes divergence major clades. Overall, these analyses suggest that lived between 1866 1679 Ma, consistent earliest...
High-resolution carbon isotope measurements of multiple stratigraphic sections in south China demonstrate that the pronounced isotopic excursion at Permian-Triassic boundary was not an isolated event but first a series large fluctuations continued throughout Early Triassic before ending abruptly early Middle Triassic. The unusual behavior cycle coincides with delayed recovery from end-Permian extinction recorded by fossils, suggesting direct relationship between Earth system function and...
Earth's surface chemical environment has evolved from an early anoxic condition to the oxic state we have today. Transitional between earlier Proterozoic world with widespread deep-water anoxia and a Phanerozoic large oxygen-utilizing animals, Neoproterozoic Era [1000 542 million years ago (Ma)] plays key role in this history. The details of Earth oxygenation, however, remain unclear. We report that through much later (<742 +/- 6 Ma), remained beneath mixed layer oceans; deeper water masses...
Spirit landed on the floor of Gusev Crater and conducted initial operations soil‐covered, rock‐strewn cratered plains underlain by olivine‐bearing basalts. Plains surface rocks are covered wind‐blown dust show evidence for enrichment soluble species as vein void‐filling materials coatings. The is result a minor amount transport deposition aqueous processes. Layered granular deposits were discovered in Columbia Hills, with outcrops that tend to dip conformably topography. interpreted be...
Molecular phylogenies of eukaryotic organisms imply patterns biological and environmental history that can be tested against the geological record. As predicted by sequence comparisons, Precambrian rocks show evidence episodic increases in diversity atmospheric oxygen concentrations. Nonetheless, complete integration two records remains elusive may require earliest macroscopic recognized as extinct experiments multicellularity.
The repeated association during the late Neoproterozoic Era of large carbon-isotopic excursions, continental glaciation, and stratigraphically anomalous carbonate precipitation provides a framework for interpreting reprise these conditions on Late Permian Earth. A paleoceanographic model that was developed to explain linked phenomena suggests overturn anoxic deep oceans introduced high concentrations carbon dioxide into surficial environments. predicted physiological climatic consequences...
The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and nearby plains within Meridiani Planum. soils consist of fine-grained basaltic sand a surface lag hematite-rich spherules, spherule fragments, other granules. Wind ripples are common. Underlying thin soil layer, exposed small impact craters troughs, flat-lying sedimentary rocks. These rocks finely laminated, rich sulfur, contain abundant sulfate salts. Small-scale cross-lamination some locations...
Simple multicellularity has evolved numerous times within the Eukarya, but complex multicellular organisms belong to only six clades: animals, embryophytic land plants, florideophyte red algae, laminarialean brown and two groups of fungi. Phylogeny genomics suggest a generalized trajectory for evolution multicellularity, beginning with co-optation existing genes adhesion. Molecular channels facilitate cell-cell transfer nutrients signaling molecules appear be critical, as this trait occurs...
An explosive episode of biological diversification occurred near the beginning Cambrian period. Evolutionary rates in have been difficult to quantify accurately because a lack high-precision ages. Currently, uranium-lead zircon geochronology is most powerful method for dating rocks age. Uranium-lead data from lower located northeast Siberia indicate that period began at approximately 544 million years ago and its oldest (Manykaian) stage lasted no less than 10 years. Other Tommotian...