Canadian rocks dating back 890 mn yrs are oldest animal fossils? Not all scientists agree If the newly discovered rocks in Canada are confirmed to be sponge fossils, they would predate oldest confirmed animal fossils by 350 million years. Sandhya Ramesh 30 July, 2021 12:09 pm IST Text Size: A+ Bengaluru: The oldest known fossils of animals date back 541 million years, which is when animals first started to appear according to fossil record. But a new discovery seems to point to much older animal fossils — that of sponges dating to 890 million years ago. The discovery, published this week in Nature journal by Canadian scientist Elizabeth C. Turner, identifies a possible fossil with microscopic tubular crystalline structure on rock surfaces. The pattern seemingly matches the expected pattern of fossilised protein in sponges.