Sunday, 17 December 2017

Cambrian Jellyfish Embryos Haven’t Evolved in “500 Million Years”

Image courtesy of the University of Bristol

Joel Kontinen

Microfossils known as Pseudooides (‘false eggs’) are the inspiration behind a story issued by the University of Bristol. Smaller than grains of sand, they nevertheless succeed in wrecking Darwinian thinking on how things are supposed to change:

Everyone wants to be with their family for Christmas, but spare a thought for a group of orphan fossils that have been separated from their parents since the dawn of animal evolution, over half a billion years ago.

Seen from a Darwinian perspective, the problem is that they haven’t changed since the Cambrian Era:

Pseudooides fossils have a segmented middle like the embryos of segmented animals, such as insects, inspiring grand theories on how complex segmented animals may have evolved.

A team of paleontologists from the University of Bristol’s School of Earth Sciences and Peking University have now peered inside the Pseudooides embryos using X-rays and found features that link them to the adult stages of another fossil group.

It turns out that these adult stages were right under the scientists’ noses all along: they have been found long ago in the same rocks as Pseudooides.

Surprisingly, these long-lost family members are not complex segmented animals at all, but ancestors of modern jellyfish.

“500 million” years is a long time for the oxymoron known as evolutionary stasis, i.e. absence of change.


University of Bristol. 2017. Fossil orphans reunited with their parents after half a billion years. (13 December).