 A key breakthrough would come when Martin Glaessner would show that fossils of soft bodied animals discovered by Reginald Sprigg during the late 1940s in the Ediacaran hills of Australia were in fact pre-Cambrian not early Cambrian as Sprigg had originally believed, making the Ediacaran biota the oldest animals known.By the end of the 20th century, paleobiology had established that the history of life extended back at least 3.5 billion years.t