Animals Emerged 350 Million Years Earlier Than Previously Thought, Fossil Discovery Suggests - Gizmodo

At 890 million years old, they could be the oldest known animal fossils on Earth.

Simple, single-celled life forms first appeared on Earth about 3.4 billion years ago, but it took a while for more complex animal life to emerge.

The Cambrian Explosion of complex lifeforms happened around 540 million years ago, which coincides with the oldest undisputed sponge fossils on record.

“If these fossils are confirmed to be sponge fossils, they would definitely be the first fossils of animals in the fossil record, thus pushing back the emergence of animals to 350 million years before the Cambrian,” Cardenas explained in an email.

Cardenas, on the other hand, said finding sponge fossils more than 250 million years before the appearance of the aforementioned steroid sponge compounds is “unexpected.” Other compounds have been found from the same period as the newly reported fossils, but “they have not been assigned to sponges yet,” he said, “although their resemblance” to the sponge compounds “is acknowledged.”.

If the new finding can be confirmed, it means sponges, and therefore complex animal life, appeared prior to the second of Earth’s two oxygenation events, namely the Neoproterozoic oxygenation event.