From the pre-Cambrian and early Cambrian, we have a collection of enigmatic fossils: the small shellies appear to be bits and pieces of partially shelled animals; there are trace fossils, the tracks of small, soft-bodied wormlike animals; and there are the very peculiar Edicaran vendobionts, which look like fronds and fans and pleated or quilted sheets. In the Cambrian, of course, we find somewhat more familiar creatures—sure, they're weird and different, but we can at least tentatively see them as precursors to the modern members of their respective phyla. It's not surprising, though, that the farther back in time we go, the stranger animals appear, and the more difficult it is to place them in our phylogenies.

So here's something cool and helpful—it looks like a vendobiont, but it's been found in the Lower Cambrian fossil beds of Chengjiang. It's also very well preserved, and has features that suggest affinities to the ctenophores.

Continue reading "Stromatoveris" (on Pharyngula)


Though it’s always a good thing when another taxon finds its place, I confess I’m relieved that some Ediacaran fauna may still be outside the Metazoa entirely:

The level of organization seen in Stromatoveris (and equivalent Ediacaran fossils) seems to transcend protistan complexity. It seems likely, therefore, that the vendobionts as currently recognized are not monophyletic. Taxa such as Ernietta and Pteridinium, built on simple modular units and apparently with an infaunal mode of life, may well be giant protistans.

It seems much more romantic that way.

Weren’t a bunch of these kinds of things found in Russia and referred to as “the small shelly fauna”? Is there any further clarity on their identification?

I think you’re thinking of the Tommotian fauna. (The “small shellies” PZ mentioned.) Here’s a random site I Googled…I make no promises that it’s remotely up to date!

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This page contains a single entry by PZ Myers published on May 8, 2006 9:45 AM.

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