Re: Early Embryos of ... Something

David Campbell (
Tue, 17 Feb 1998 17:31:40 -0400

>Last weekend, a friend told me of a science news item he'd seen.
>Someone had found rocks apparently bearing a lot of microfossils.
>In this case, the microfossils were little clusters of "nodules,"
>the clusters always containing 1, 2, 4, 8, 16 etc. members. This
>adherence to powers of two strikingly suggests embryos in the early
>stages of division. No indication what these were embryos OF, though.
>What makes it more interesting, if my friend remembers correctly,
>is that what appears to be multicellular embryos date from a period
>when no life at all was thought to exist, much less multicellular
>stuff. Anyone on the list hear of this news item?

The volume of Nature with this item in it has finally arrived at the
Geology Library here. "No life at all" is wrong (though quite possibly
part of a news report). Multicellular algae were previously reported from
this deposit, as well as from much older deposits (about half a billion to
a billion years older), and bacteria go back about 3 billion years before
these. A similar article in Science (which won't be in our library for a
while, but which was mentioned in the summary in Nature) reported
multicellular animals, namely sponges. However, the embryos appear to
represent more complex animals than sponges. There are two possible
reasons why the animals have not been found. First, there has not been
much looking done. Secondly, the preservation (phosphatization) of the
embryos typically acts on a very small scale and may not have been as good
at preserving larvae or adults.
There are reports of older trace fossils (burrows, etc.), but no
definite body fossils of multicellular animals had been found in rocks this

David C.