Researchers Find Fossilized Embryos That Are Over 500 Million Years Old

Posted on April 10, 2014

Cambrian Embryo fossil

Researchers at the University of Missouri have found rare, fossilized embryos that are over 500 million years old. The fossils date back to the Cambrian Period, a time when most phyla of marine invertebrates first appeared in the fossil record. Most fossils show the organisms' skeletal structure. Finding preserved soft-tissue of organisms is very rare. An image of a Cambrian embryo fossil exposed by acid etching on the rock surface is pictured above. The scientists say the polygonal structure on the surface is indicative of the blastula stage of development.

James Schiffbauer, assistant professor of geological sciences in the MU College of Arts and Science, said in the announcement, "Before the Ediacaran and Cambrian Periods, organisms were unicellular and simple. The Cambrian Period, which occurred between 540 million and 485 million years ago, ushered in the advent of shells. Over time, shells and exoskeletons can be fossilized, giving scientists clues into how organisms existed millions of years ago. This adaptation provided protection and structural integrity for organisms. My work focuses on those harder-to-find, soft-tissue organisms that weren't preserved quite as easily and aren't quite as plentiful."

The fossilized embryos the researchers found were significantly smaller than other fossil embryos from the same time period, suggesting they represent an undescribed organism. The fossils were found in the lower Cambrian Shuijingtuo Formation, Hubei Province, South China. Schiffbauer and his team, including Jesse Broce, a Huggins Scholar doctoral student in the Department of Geological Sciences at MU, now are studying the fossilized embryos. Additional research will focus on identifying the parents of these embryos, and their evolutionary position.

Schiffbauer also says, "Something obviously went wrong in these fossils. Our Earth has a pretty good way of cleaning up after things die. Here, the cells' self-destructive mechanisms didn't happen, and these soft tissues could be preserved. While studying the fossils we collected, we found over 140 spherically shaped fossils, some of which include features that are reminiscent of division stage embryos, essentially frozen in time."

The researchers published their research in a special issue of the Journal of Paleontology.

Photo: Broce et al.

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