Pygidium (tail shield) of a large dechenellid trilobite attached to ventrally flexed articulated thorax + cephalon (out of view). Maximum width of pygidium ~24 mm. The specimen has been blackened with photo opaque and coated with sublimated ammonium chloride to accentuate topographical features, such as small elevated granules. The axial region shows severe distortion of individual "rings" with bifurcation, misalignment, and asymmetric development. The pleural fields are similarly disrupted, particularly in the posterior half. Specimen is in the Invertebrate Palaeontology collections of the Royal Ontario Museum. Figured by Rudkin 1985 (Canadian Journal of Earth Sciences, 22 (479-483).
#Palaeo metaphor for the times: an example of how things can go very wrong. Monodechenella macrocephala pygidium w #aberrant exoskeletal #development of axis & pleurae. Unknown how this might have been expressed in underlying somites, gut, limbs, etc. M. #Devonian (~387 MYA), NYS #TrilobiteTuesday