Fig. 1 in Comparative cranial osteology of subadult eucentrosauran ceratopsid dinosaurs from the Two Medicine Formation, Montana, indicates sequence of ornamentation development and complex supraorbital ontogenetic change

Fig. 1. Lateral views of articulated crania of subadult eucentrosaurans from the Campanian Two Medicine Formation, Montana, USA. A. Einiosaurus procurvicornis Sampson, 1995, MOR 456 8-8-87-1. B. Eucentrosauran (Einiosaurus procurvicornis or Achelousaurus horneri Sampson, 1995), MOR 591. Photographs (A1 and B1), osteological line drawings (A2, B2). Face of MOR 591 mirrored, with parietosquamosal frill superimposed. The contact outlines between the postorbital, jugal, and squamosal in A2 are estimated due to lack of externally visible sutures and may appear different from MOR 591 due to some breaks and gaps. P4–P7, parietal processes.