The Ediacaran fossils of what we used to call the "Vendian" period - just before Cambrian - were called "fauna" first I heard of them, at seven or eight years of age early in the Reagan era. Those kids' books made sure to distinguish this Classical word from "flora", meaning flourishing flower or just plant. So Rachel Wood's thesis isn't new to me.
What's new-ish is the biochemical evidence for animal life: the cholesterol found as a waste-product. That's the miracle from my perspective; I had no idea this complexity of organic matter could survive 600 million years. Also 'tis nice to define which of these is fauna and which, flora. I'm told there used to be lively debates over these or even if they were like slime molds.
Wood is taking these constraints and suggesting that much Cambrian fauna descends from Ediacaran fauna. Which also strikes me as a starting assumption. There might not have been solid proof for "they evolved somehow and we don't know yet" but that's not where the burden lies. If they were all just zapped on our planet by Lord God YHWH, or dumped by Yakoob in his space ship from Kolob, that is extraordinary so the argument you have to make. Wood still doesn't have "proof", which as we all know doesn't exist outside mathematics; but she marshals some evidence. Thus constraining Yakoob.
Ikaria is her best evidence here as it looks like a segmented worm. That's the ancestor to all the arthopods and protochordates in the Cambrian. I still think Blink Of An Eye is the spark to Cambrian diversity and (probable) mass extinction of the unadapted lifeforms before it. But then, a worm doesn't need eyes to burrow.
Anyway, what Wood has done doesn't change my Reagan-era mind, but it does bolster and constrain it. Which - I am gathering - has been sorely needed, for others, who actually work in this field.
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