Fig. 3.

Detector count distributions assigned to individual anatomical categories for eight elements: Fe, Mn, Zn, Cu, Ca, Si, P, and S. The frequency of pixels giving a detector intensity response is plotted as a function of counts. “Bone” refers to combined areas of postcranial skeleton. (Further method details are in SI Text in Synchrotron Rapid Scanning X-ray Fluorescence.) For all elements besides Mn, the histolines for Archaeopteryx bone, claws, teeth, and skull are clearly different from the embedding sediment slab, showing that a chemical fossil indeed endures. The feather is far less distinct from the sediment, consistent with diminished preservation of soft tissue relative to bone.