When did the earliest creatures emerge on our planet? According to fossil evidence, the initial forms of animals arose approximately 570 million years ago and quickly multiplied during the Cambrian explosion, which occurred around 539-485 million years ago. However, according to the molecular clock, which calculates the genetic changes over time to determine the oldest common ancestor of living animals, the first animals likely evolved around 800 million years ago.
Researchers have recently adopted a new method of inquiry, inquiring about the timing of suitable circumstances for the preservation of animal fossils. It is believed that the earliest animals did not possess mineral-based shells or skeletons, making it necessary for extremely favorable conditions to be present in order for them to become fossilized, similar to the renowned Burgess Shale deposits in the Canadian Rockies, which are estimated to be 500 million years old.
The examination of rocks similar to those found in the Burgess Shale showed that specific types of clay can improve the likelihood of preserving soft-bodied fossils. After studying numerous deposits dating back 800 million years, the scientists determined that only three locations – Nunavut in Canada, Siberia in Russia, and Svalbard in Norway – met these conditions. However, none of these sites contained any animal fossils.
According to a study published in Trends in Ecology and Evolution, scientists believe that animals may have first emerged 789 million years ago. They plan to continue their research by analyzing younger rock samples in order to improve the accuracy of this estimate.