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Chitin-Protein Residues Found in Paleozoic Scorpion Fossil Print
Wednesday, 02 March 2011 17:15

A big surprise is revealed in this soft x-ray absorption image of exoskeleton from a 310-million-year-old scorpion fossil. The brighter areas map the abundance of nitrogen from chitin, which scientists previously believed couldn't endure in extremely old fossils. For scale, the black bar is one-millionth of a meter. (Image courtesy of Carnegie Institution)

Scientists from Carnegie Institution of Washington and Berkeley Lab used the scanning transmission x-ray microscope on ALS Beamline 5.3.2 to detect remnants of protein and chitin in the exoskeleton of a 417-million-year-old fossil of an extinct mega-scorpion, a discovery that reveals organic material in fossils several hundred million years older than previously found chitin-containing fossils.

The images were analyzed using x-ray absorption near edge structure spectroscopy, which identifies atoms of individual elements, within their molecular framework, by probing their electrons at distinctive energies. This work upends the conventional view formed by previous studies, that organic material does not endure in extremely old fossils because it is readily broken down by microbes and other natural processes.

This study focused on fossil remains of two Paleozoic arthropods: a scorpion unearthed in a cave in northern Illinois, and a eurypterid plucked from a quarry in Ontario, Canada. In both fossils, analyses revealed that much of the carbon, nitrogen, and oxygen—elements which Beamline 5.3.2 is specially tuned to detect—in the exoskeleton are from chitin-protein complex.

“The microscope at the Advanced Light Source is the star in this research,” says the publication’s first author George Cody. “It opens up new ways of conducting molecular paleontology research.”

The preservation of chitin-protein residues in extremely old fossils likely depends on the build up of fatty acids on a scaffold of chitin-protein molecules. This layer saves the remaining matrix of chitin and proteins from degradation by microorganisms even after 500 million years.

 


 

Work performed on ALS Beamline 5.3.2

Citation: G.D. Cody, N.S. Gupta, D.E.G. Briggs, A.L.D. Kilcoyne, R.E. Summons, F. Kenig, R.E. Plotnick, and A.C. Scott, "Molecular signature of chitin-protein complex in Paleozoic arthropods," Geology 39 (3), 255-258 (2010).