Repeated recalibrations and retests, using ever more sophisticated techniques and equipment, cannot shift that date. With modern, extremely precise, methods, error bars are often only 1% or so.
The fossil record is fundamental to an understanding of evolution.
Early geologists, in the 1700s and 1800s, noticed how fossils seemed to occur in sequences: certain assemblages of fossils were always found below other assemblages. Since 1859, paleontologists, or fossil experts, have searched the world for fossils.
In the past 150 years they have not found any fossils that Darwin would not have expected.
The review had some limitations but the fact that only three studies were found, despite a thorough search, supports the authors' conclusions.
Age estimates can be cross-tested by using different isotope pairs.
Fossils document the order of appearance of groups and they tell us about some of the amazing plants and animals that died out long ago.
Fossils can also show us how major crises, such as mass extinctions, happened, and how life recovered after them.
ASSIA, Care Data, MEDLINE, Child Data, CINAHL, EMBASE, Psyc INFO, SIGLE, the Social Sciences Citation Index and TRIP were searched from inception to March 2004; the search terms were reported.
Textbooks published between 19 were searched by hand. No inclusion criteria for the study designs were specified, although review articles, consensus statements and expert opinions were excluded.