http://arxiv.org/abs/1505.08125
Major discrepancies have been noted for some time between fossil ages and molecular divergence dates for a variety of taxa. Recently, systematic trends within avian clades have been uncovered. The trends show that the disparity is much larger for mitochondrial DNA than for nuclear DNA; also that it is larger for crown fossil dates than stem fossil dates. It was argued that this pattern is largely inconsistent with incompleteness of the fossil record as the principal driver of the disparity. A case is presented that given the expected mutations from a fluctuating background of astrophysical radiation from such sources as supernovae, the rate of molecular clocks is variable and should increase into the past. This is a possible explanation for the disparity. One test of this hypothesis is to look for an acceleration of molecular clocks 2 to 2.5 Ma due to a probable moderately nearby supernova at that time. Another is to look for reduced disparity in benthic organisms of the deep ocean.
A. Melott
Mon, 1 Jun 15
32/62
Comments: Accepted for Earth and Life II