Biosignatures & Paleobiology: November 2007

Researchers from NAI's University of Hawai'i Team and their colleagues have a new paper in Geobiology reviewing recent work on the climatic, geochemical, and ecological events that preceded animal fossils, considering their portent for metazoan evolution. They also consider recent published research on the nature and chronology of the earliest fossil record of metazoans, and on the molecular-based analysis that yielded dates older than the last 35 million years of the Precambrian for the appearance of major animal groups.

[Source: NAI Newsletter]

The goal of research funded under the interdisciplinary P2C2 solicitation is to utilize key geological, chemical, and biological records of climate system variability to provide insights into the mechanisms and rate of change that characterized Earth's past climate variability, the sensitivity of Earth's climate system to changes in forcing, and the response of key components of the Earth system to these changes.

NAI's Astrobiology Drilling Program supported researchers in 2004 to obtain subsurface core samples from the Hamersley Basin in Western Australia. Those samples, representing the time just before the Great Oxidation Event, have been analyzed, and two research papers detailing the results (Anbar, et al. and Kaufman, et al.) appear in September 28, 2007 issue of Science. Both groups found unexpected, correlated changes that reveal the presence of small but significant amounts of O2 in the environment 2.5 billion years ago, ~50-100 milion years before the Great Oxidation Event, and a shift from lower O2 abundance prior to that time. [Source: NAI Newsletter]

Researchers from NAI's Carnegie Institution of Washington Team have a paper in Nature describing evidence that Earth's Mesoarchean atmosphere (3.2 and 2.8 Gya) possessed very low amounts oxygen. These findings contrast with prior claims that Earth's atmosphere underwent its first rise in oxygen during the Mesoarchean, and indicate that oxygen first rose above parts per million levels sometime between 2.45 and 2.4 billion years ago. [Source: NAI Newsletter]

NAI's Marine Biological Laboratory Team has a new paper in Science detailing aspects of population structure for microbial communities at two neighboring hydrothermal vents. Using environmental DNA sequencing techniques, they found the two populations reflect the geochemical conditions of each vent. [Source: NAI Newsletter]