Dr. Steven Novella

These have to do with ancient evolution.

Are you ready?

Here we go.

Item number one.

Okay.

Item number two, a review of fossil evidence shows that early eukaryotes, 1.75 to 1.4 billion years ago, were free-swimming organisms living mostly near the surface of the ocean.

And item number three, a unique fossil find from China indicates that chordates, the group that includes vertebrates, existed in the late Ediacarian period prior to the Cambrian explosion.

Evan, go first.

And Evan, since you're going first, if you have any questions, I'll hear them.

Right, and the Cambrian period, what, like, you know, a little bit over 500 million years ago, that's when multicellular life exploded, you know, in the fossil record.

So just to clarify my wording there, so don't read the from Canada, just read it without the parenthetical.

An assemblage of Ediacaran fossils once thought to be a failed Precambrian offshoot, right?

So Ediacaran fossils were once thought were just a failed attempt at multicellularity, but then the real one took off in the Cambrian explosion.

But now they're saying these fossils are like, no, we're seeing actual ancestors to extant groups in the Ediacaran fossils.

Right.

That's not complicated at all.

Yeah, so most animals have bilateral symmetry.

And that's the largest, basically, group of animals.

And so they're saying that one of these critters in these pre-Cambrian Ediacaran fossils from Canada...

is actually a bilaterian animal, an ancestor of most animals alive today.