Dr Tom Kemp

The great majority of studies in evolutionary biology concern Microevolution- the relatively short-term processes that affect successive generations of organisms in living populations. They include the ecology of adaptation; the genetics of variation; the molecular basis of mutation; and the changing distribution of genes in interbreeding populations to the point of speciation. In contrast, palaeobiologists are concerned with Macroevolution – the processes and events that occur over vastly longer time-scales, from tens of thousands to hundreds of millions of years. Molecular sequence data provides indirect evidence such as creating phylogenies of modern organisms, but the fossil record is the only direct evidence about what really happened over these periods of time that life on earth has been evolving, and how the great diversity we see around us today came about.

 

I shall look at what the fossil record actually consists of, how complete it is, and how much detail about evolution it can reveal. In this light I identify the particular evolutionary phenomena which would not be known about without the evidence of fossils.  (i) Why species last for millions of years in stasis? (ii) What drives the pattern of global biotic diversity change over the course of evolutionary history? (iii) What are the causes and consequences of the mass extinctions that suddenly wipe out a majority of species world-wide?  (iv) What drives certain lineages to undergo enough evolutionary change over time to be recognised as new higher taxa, such as the mammals during the Permo-Triassic, and arthropods in the Cambrian?