A team of palaeontologists, lead by Mike Foote from the University of Chicago, has attempted to measure how accurate the fossil record really is. For the last 20 years two camps of scientists have been arguing over the dates of origin for various organisms. The debate centers on two different approaches to finding the time when one particular group split from another.
Molecular biologists use various molecules such as DNA collected from living animals.
They compare the same molecules from two different organisms looking for similarities and differences in structure. Differences between molecules measures how long the two groups have been evolving independently of each other. Palaeontologists use fossils to track back through time to find when new groups of organisms first appeared. This technique assumes that the fossil record provides an accurate account of the evolutionary history of organisms. Conflicts between divergence dates derived from the two different techniques often occur, particularly for organisms that are poorly represented in the fossil record.