The missing fossils argument; new very early Ediacaran (Introduction)

by David Turell , Monday, October 21, 2024, 16:25 (17 hours, 14 minutes ago) @ David Turell

Lived in a mat of algae and bacteria:

https://www.sciencealert.com/this-strange-fleshy-blob-is-one-of-earths-earliest-animals...

"The traces of one of these early complex creatures has just been unearthed in the South Australian outback, and its intricate design rivals all other fossils before it.

"...it's a flattened, circular blob with a mysterious question mark shape for a butt crack.

***

"They know it's an animal because of the features it shares with living members of the kingdom: multiple cells, the ability to move, and a body plan organized into different halves.

"And they found not one, but more than a dozen of these things, along with trace fossils – the imprints of their blobby bodies preserved forever in the now-petrified mat of microscopic algae and bacteria that Quaestio once lurked in.

"Some of these impressions show slightly offset outlines distinct from the harder edges of the animal's imprint, evidence that these were among the first animals capable of moving on their own.

"'One of the most exciting moments… was when we flipped over a rock, brushed it off, and spotted what was obviously a trace fossil behind a Quaestio specimen – a clear sign that the organism was motile; it could move," Harvard University evolutionary biologist Ian Hughes says.

"A little smaller than the size of a human palm, the Quaestio's distinctive question-mark shape – for which it was named – distinguishes a left and right side, a sign of bilateral symmetry, along with a crucial asymmetrical twist.

"'There aren't other fossils from this time that have shown this type of organization so definitively," Florida State University geologist Scott Evans says.

"Asymmetry is a component of modern-day animals, including humans, and Quaestio might just be the first to evolve this mathematically complicated quirk.

Comment: the appearance of animals had to happen at some point. Note that it looks nothing like later forms.