Dec. 5, 2006 — The first fossils of half-billion-year-old clusters of soft-shelled eggs have been found preserved in a strange new way in south China — some of the eggs were even caught in the act of dividing.
The three-dimensional clusters of petrified eggs from invertebrate animals that lived in a sea 501 million to 510 million years ago are preserved in silica — glass essentially. Jih-Pai Lin, an Ohio State University paleontologist, explained this is a totally unexpected way for soft eggs to fossilize and survive for eons.
Lin is the lead author of a report on the egg clusters published in the December issue of the journal Geology.
The discovery means there are probably even more early eggs and embryos fossilized in ancient rocks. Fossil hunters just need to keep in mind the different ways they might be preserved, and therefore the different types of rocks in which they might be found.
"This is by far the oldest known intact egg cluster reported," Lin told Discovery News. Other eggs have been found of a similar age, but they are more dispersed, which is far less revealing about the animal that laid the eggs, he explained.
The egg cluster was likely preserved in the very spot it was laid on the sea floor, which tells us something about the strategy the unknown early animal used to reproduce, Lin said. It could also hint at how much energy the animal had for making eggs, and therefore how much food was available on the ancient sea floor at that very distant time, he said.
"(The clusters) provide a little bit more detail on the picture of Cambrian ecology," said Lin, referring to the geologic era when life first exploded, starting some 543 million years ago.
That said, other paleontologists are more impressed by the fact that eggs, and possibly even embryos, of ancient organisms can now be sought in silica-based rocks.
