Born in Vienna in 1885, Fritz Illner learned the profession of a road construction engineer. In 1920, he married Anna Glas, with whom he was to have two daughters – Herta (born on 27 December 1921) and Rita (born on 19 December 1923). As part of his employment, Fritz Illner spent longer periods abroad. Presumably during his working stay in Turkey between 1928 and 1931, he collected four fossils – three ammonites and one inoceramus (a type of shell) from the Cretaceous period. From 1933, Fritz and Anna Illner lived in Nice, while for the time being, their children stayed with their aunt, Anna Illner's sister, Irma Bondy in Vienna.

After the "Anschluss" of Austria to the National Socialist German Reich, the family was subjected to anti-Semitic persecution in Vienna. In November 1938, the children finally left Vienna together with their aunt and fled to Nice; the whereabouts of Irma Bondy are unknown. Before fleeing Vienna, Irma Bondy sold her brother-in-law's fossils on his behalf to the Geological-Palaeontological Department of the Natural History Museum Vienna (NHM) on 13 June 1938. With the beginning of the Second World War, the Illner family was no longer safe in France either. As German-speaking foreigners, the Illners were considered "nationals of the enemy powers" (ressortissants ennemis) and were temporarily detained in the internment camp in Gurs (Camp de Gurs) in May 1940. Soon the family was allowed to leave the camp and, under police supervision, live again in Nice, where Herta and Rita Illner were interned in barracks from the end of September to the beginning of October 1942 until they received further residence permits. As a result of the occupation of Nice by the German Wehrmacht in September 1943, the Gestapo arrested Anna and Fritz Illner on 18 March 1944. Their children had obviously learned of the impending arrest in advance and were able to go into hiding with forged documents. Initially interned in the Drancy assembly and transit camp, the parents were deported to the Auschwitz extermination camp on 13 April 1944 and were probably murdered immediately after their arrival.

The daughters survived the National Socialist persecution and were able to return to Nice as early as April 1945. While Rita married and emigrated to Israel, Herta remained in Nice until 1958, before going to stay with her sister in Israel. At Rita Grabowski's request, her parents Anna and Fritz Illner were declared dead in 1959. In 1960, Herta Illner returned to Vienna, where she died in 1993. Based on the results of systematic provenance research in the Geological-Palaeontological Department of the NHM, the Art Restitution Advisory Board recommended in October 2019 that the collection be restituted to the legal successors of Fritz Illner. At their request, the objects were handed over by the Austrian Embassy in Tel Aviv in December 2022, and the fossils were loaned to the Steinhardt Museum of Natural History at Tel Aviv University.