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.

Source:

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