The oldest known digestive system consisting of both paired digestive glands and a crop from exceptionally preserved trilobites of the Guanshan Biota (Early Cambrian, China)
(A) Photograph of entire specimen. (B) SEM image of crop outlined in (A). (C) SEM image overlain by elemental mapping: Ti, Al (fuchsia); N, K (red); C (dark blue); Cu (pink); S (violet); P (light blue); Ca (blue-green); Na (yellow-green); Mg (orange); Fe (yellow); Si (cyan); O (green). (D) Elemental map of just iron in area shown in B and C. (E) SEM image of area outlined in (B). (F) SEM image overlain by elemental mapping: Fe (yellow); Si (cyan). (G) Elemental map of iron in area shown in E and F. Scale bar for (A) = 5 mm; scale bar for (B-D) = 1 mm; scale bar for (E-G) = 500 microns. See Figs O-P in S1 File for additional elemental maps for this specimen.