I was watching a TV show about the Cambrian Explosion the other evening. This was a period in Earth’s history, about 500 million years ago, when the fossil record suddenly blossoms: there are all kinds of animals, all over the place – trilobites, things that look like early fish, everything.
Why this explosion of life? There are lots of theories, and some are better than others. The late Stephen Jay Gould wrote a book (which I devoured back in the early 1990s) called “Wonderful Life,” which analyzed a group of fossils called the Burgess Shale, and concluded that something at an early point of Earth’s history caused a huge proliferation of life forms, which have narrowed and died down since then.
Do you see? Instead of the usual tree arrangement – simple life branching out into forms of more and more complexity – Gould theorized that the tree exploded into a forest early on, and that the forest has become thinner and thinner since then.
His theory has failed on many points. He misinterpreted a number of the Burgess fossils; one he turned upside down (he had it walking on long spine-like legs; turns out that the spines were – of course! – on its back).
Gould portrayed early life on earth as a drowsy microbial cloud, purring and oozing. Along the way, and in among the other creatures, he mentions an especially interesting early form of life called only “the Ediacaran fauna.”
These are interesting. For maybe fifty million years, they were pretty much everywhere on earth. Some were big globular things, and some were flat. They lay in water, or on shoals (we don’t really know), and basked. Maybe some of them remotely resembled jellyfish; some of them (maybe) resembled modern creatures called sea pens, big wavy feathery things that anchor themselves in the ocean floor.
Ediacarans were soft, and didn’t leave fossils very often; it took a lot of looking to find them. They have been found on every continent now.
I like thinking of those ancient seas – pink? why not? – under skies filled with hazy tropical clouds, with waving forests of feathery creatures just under the water, and big flotillas of lazy pancakes and big pink beachballs bobbing in the surf.
Because one of those big pink beachballs may have been your grandmother.
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