Fig. 2.

False color SRS-XRF map of Archaeopteryx. Color code is calcium, red; Zn, green; and Mn, blue. Higher intensities correspond to higher concentrations; see Table 1 for concentrations. Host rock is limestone, and hence high calcium surrounds the fossil. Blue flecks on the surface result from the presence of tiny precipitates of Mn(IV) oxide minerals that are ubiquitous along bedding planes and within fractures. There is some zinc associated with the mineral precipitates, but almost all of the Zn inventory in this image is associated with the Archaeopteryx bone material. Zinc apparently was present in appreciable concentrations in the original bone (as in many extant organisms) and has been well sequestered within the bone over 150 million years of burial.