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.