In her obituary in Nature, Richard L. Cifelli wrote that "Much of what we know about the origin and early evolution of mammals stems, directly or indirectly, from [her work]".
In 1928, her father, Franciszek Kielan, was offered a job for the Association of Agriculture and Trade Cooperatives in Warsaw, to which her family moved for five years.
She began her studies in Warsaw, following the destruction after the war when the Nazis had attempted to completely destroy the city, resulting in the Department of Geology joining the ruins.
[1] Her work included the study of Devonian and Ordovician trilobites from Central Europe (Poland and Czech Republic), leading several Polish-Mongolian paleontological expeditions to the Gobi Desert, and the discovery of new species of crocodiles, lizards, turtles, dinosaurs (notably Deinocheirus), birds and multituberculates.
The excavations, led by the geologist Jan Czarnocki, took place in Poland's Świętokrzyskie Mountains in exposures of Middle Devonian strata.
The group's work involved digging for soft rock and rinsing away the sediment, consisting of yellow marl, in running water while using a sieve to collect any fossils that were present.
She returned to specific sites in the Świętokrzyskie Mountains over the next three summers to continue developing her collection, which grew to over one hundred trilobite specimens.
[6][7] Kielan-Jaworowska has added a great deal of contribution to monographs that detail findings of fossils and wrote her own book, Hunting for Dinosaurs, which give brief descriptions of her paleontological endeavors in the Gobi Desert.
In 1982, she stepped down from her position to undertake a visiting professorship at the Musée national d’Histoire naturelle in Paris, which lasted for two years.
Kielan-Jaworowska's co-author, Zhe-Xi Lou, describes her contribution to paleontology as unmatched by any living experts, and that "in the whole of Mesozoic mammalian studies for the last 100 years, only the late American paleontologist George Gaylord Simpson would be her equal".
"She is the rarest among the rare – she has been a leader in making important scientific contributions, and also a gregarious and charismatic figure, both of which have made paleontology a better science, and paleontologists worldwide a better community.
[11] A number of extinct animals have been named in her honour including Kielanodon, Zofiabaatar, Kielantherium, Zofiagale[14] as well as Indobaatar zofiae.