Final answer:
The oldest known fossil among the mentioned species is a 650 million-year-old sponge-like creature from South Australia, predating other fossils such as the Coronacollina acula and the trilobites.
Step-by-step explanation:
The earliest known fossil among the species mentioned is a sponge-like creature from South Australia that dates back 650 million years. These ancient fossils may represent the oldest evidence of animal life on Earth, predating the great ice age extinction event between the Cryogenian period and the Ediacaran period. Previously, most scientists believed that no animal life existed before the Ediacaran period, so this finding, if validated, would shift our understanding of the evolution time scale.
Trilobites first appeared over 500 million years ago, which is significantly later than the sponge-like creatures. The Coronacollina acula, a thimble-shaped sponge-like fossil with hard body parts, is dated at 560 million years ago. This discovery is notable for indicating the presence of hard body parts during that time but does not precede the potential Cryogenian fossils.
Trilobite fossils are also well known, but they first appear in the fossil record around 521 million years ago. While they were a dominant marine ecosystem component during the Cambrian period, they do not compete with the age of the previously mentioned sponge-like creatures.
Therefore, based on the information provided, the fossil of the sponge-like creature predating the Cryogenian period's end is the oldest known fossil among the mentioned species.