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) Palaeolenus lantenoisi showing evidence of crop, digestive glands, alimentary canal along thorax, and excreted waste posterior to pygidium, GLF WLQ 228A. (B) Line drawing of (A). Cr = crop; cd = cephalic digestive glands; td = thoracic digestive glands. (C) Palaeolenus lantenoisi, showing crop cavity and antennae but no alimentary canal. (D) Palaeolenus lantenoisi, showing antennae, crop and alimentary canal but not preserving obvious digestive glands. (E) Line drawing of (D). Cr = crop; ac = alimentary canal. (F) Palaeolenus lantenoisi, showing crop cavity and only diffuse iron staining on thorax, GLF WLQ 174. (G) Palaeolenus lantenoisi, showing crop and no additional iron staining, GLF WLQ 214A. (H) Redlichia mansuyi showing cavity where crop would be located, GLF WLQ 216A. (I) Redlichia mansuyi showing crop and some additional iron staining, GLF WLQ 245A. Scale bar for (A), (H-I) = 5 mm; scale bar for all other = 1 mm.