An extinction event is a sharp decrease in the diversity and abundance of macroscopic life. Major extinctions are generally caused by a combination of phenomena such as e.g. large-scale volcanism, climate and sea level change and meteoritic impacts. During mass extinctions, it has been observed that the middle and even the upper layers of the ocean may become deficient or totally lacking in oxygen, a process known as oceanic anoxic event. Although such events have not happened for millions of years, the geological record shows that they occurred many times in the past and that they played a major role in mass extinctions. Based on a multidisciplinary approach our research is aimed at better understanding the dynamics of mass extinctions, and, in particular, of oceanic anoxic events.