Jennifer A. Clack. 3 November 1947—26 March 2020

Abstract

Jennifer Clack (née Agnew) dedicated her entire research career of more than 40 years to the fish-tetrapod transition, the evolutionary process during the Devonian and Carboniferous periods that transformed a lineage of lobe-finned fishes into the earliest land vertebrates. She was widely regarded as the world leader in this field. During an expedition in the summer of 1987 to the Late Devonian vertebrate localities of East Greenland, Clack collected numerous fossils of two of the earliest tetrapods, Acanthostega and Ichthyostega , which revolutionized the understanding of these animals and created a surge of renewed interest in what had previously been a small and somnolent research area. However, much of her work focused on the Carboniferous, the time when the group underwent its first major diversification and the amphibian and amniote lineages first appeared. Here too she produced a stream of ground-breaking discoveries. She published close to 100 primary research papers, many in flagship journals, as well as numerous popular articles and the influential textbook Gaining Ground . Modest and unassuming in person, and unfailingly supportive towards young scientists, Jennifer Clack was enormously respected and helped to make the entire research field into a more open, collaborative, and welcoming environment.