A geologist may have uncovered the oldest sign of animal life on Earth: sponge fossils that potentially date back 890 million years.
â€œThe fossil record you see in a museum or geology teaching lab, fossils of animals, appear in the rock record in rocks that are younger than 540 million years,â€ Turner told The Washington Post.
Examined under a microscope, the tiny sections of rock Turner uncovered contain a meshwork of three-dimensional structures â€” branching out in a distinctive way and rejoining â€” that closely resembles modern sponge skeletons.
Given that the sponge is among the most basic forms of animal life, â€œif weâ€™re going to find early animals, it seems reasonable that theyâ€™re going to be spongelike,â€ Turner said in a Zoom interview.
Turner said it is possible the sponges pre-date these two major Earth system events, in part because modern rock records show sponges can be tolerant of low oxygen levels.
In the past five years or so, scientists have extensively researched how sponges get preserved â€” in what Turner describes as â€œa race between decay and preservation of their soft tissues.â€ Theyâ€™ve experimented on modern sponges and worked on sponge preservation in ancient rocks, â€œall of which is very, very closely related to the structure that I describe,â€ Turner said.