Dickinsonia

You can see what was inside them.

Compared to the Dickinsonia, these may as well have been screaming at us.

Outlines and raised fossils of the monsters we've been talking about right there, etched in shale.

Honestly, amazing.

Our molecular clock analyzes show how much further back their evolutionary history could extend.

Dickinsonia costata, a ribbed ediacaran organism that lived around 550 million years ago.

Verisimilis at English Wikipedia, cc by sa 3.0 slash cc by 2.5. Did animals live before snowball earth? An origin between 800 and 700 million years ago would place early animals before or during the Cryogenian glaciations known as Snowball Earth, which took hold around 720 million years ago.

Whether they weathered those conditions, or evolved in the run-up to them, is now wide open.

Repeated impressions, disturbed mats, and winding traces indicate movement by at least some animals.

Fossils associated with Dickinsonia have been interpreted as feeding traces left while the organism moved across microbial surfaces.

Organic molecules preserved with Dickinsonia also support an animal affinity, although classification at finer levels remains debated.

Trace fossils are especially important because behavior can reveal an animal even when its body is absent.

A path through sediment records muscles, coordination, and interaction with a surface.