Meteorites and impacts through geological time

Geological rhythms and cometary impacts.

Time-series analysis reveals two dominant, stable long-term periodicities approximately equal to 33 +/- 3 and 260 +/- 25 million years in the known series of geological and biological upheavals during the Phanerozoic Eon. Because the cycles of these episodes agree in period and phase with the cycles of impact cratering on Earth, these results suggest that periodic comet impacts strongly influen...

Climate on Geological Time Scales

JULY 2003, GSA TODAY ABSTRACT Atmospheric levels of CO2 are commonly assumed to be a main driver of global climate. Independent empirical evidence suggests that the galactic cosmic ray flux (CRF) is linked to climate variability. Both drivers are presently discussed in the context of daily to millennial variations, although they should also operate over geological time scales. Here we analyze t...

Completeness metrics and the quality of the sauropodomorph fossil record through geological and historical time

—Despite increasing concerns about the effect of sampling biases on our reading of the fossil record, few studies have considered the completeness of the fossil remains themselves, and those that have tend to apply non-quantitative measures of preservation quality. Here we outline two new types of metric for quantifying the completeness of the fossil remains of taxa through time, using sauropod...

Conflict between Local and Global Changes in Plant Diversity through Geological Time

Reliable measurement of the original diversity of paleovegetation must account for many influences: the amount of time and space represented by the sample, the number of plant parts in the sample, the stature of the paleovegetation in relation to sample area, and the preseruational quality of the sample, as well as the number of species in the source community and their relative abundances. Pla...

Title Microbial phophatization through deep geological time and its implications to searching for life on MARS