Cambrian Explosion: very early sponges (Introduction)

by David Turell @, Wednesday, July 08, 2015, 18:50 (1725 days ago) @ David Turell

Still not very complex as compared to Cambrian animals, and this ability to find soft forms negates the argument that previously deeloped complex soft forms were never fossilized, making the Cambrian look like an explosion:

"'Fundamental traits in sponges were not suddenly appearing in the Cambrian Period, which is when many think these traits were evolving, but many million years earlier," Bottjer said. "To reveal these types of findings, you have to use pretty high-tech approaches and work with the best people around the world."

"Since 1999, Bottjer has worked with a team of researchers from the Nanjing Institute of Geology and Palaeontology (Chinese Academy of Sciences) and the California Institute of Technology, as well as the European Synchrotron Radiation Facility in Grenoble, France.

"Team members in China dissolved several 600 million-year-old rocks, which are regularly mined for Chinese agricultural fertilizer from the Doushantuo rock formation in southwestern China's Guizhou Province. They then used a gentle acid bath to reveal tiny fossils made of calcium phosphate and a Scanning Electron Microscope (SEM) to determine which of those fossils were preserved well enough to merit analysis with the synchrotron.

"'The preservation in these Doushantuo rocks is extremely fine—and you can even see individual cells with the SEM," Bottjer said. "Once a specimen worthy of further study is found, synchrotron microscopy is used to create very, very detailed images of the fossil in two and three dimensions. From these images we are then able to see what types of animals these fossils represent.'"

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