Photographie Atlas of Styracosaurus albertensis 



Introduction 



Ceratopsids were large bodied (4-8 m long), vaguely rhinoceros-like quadrupedal dinosaurs. They 

 were among the most common herbivorous dinosaurs of the Late Cretaceous, comprising 12 genera 

 distributed equally between the subfamilies Centrosaurinae and Chasmosaurinae (Dodson et al. 

 2004). Some genera, such as Triceratops (Ostrom and Wellnhofer 1986) and Centrosaurus (Brown 

 1917, Lull 1933) are represented by numerous skulls and postcranial skeletons, but most taxa are 

 incompletely known. Until recently, one of the rarest ceratopsids was Styracosaurus albertensis, a 

 modest sized centrosaurine of about 5.5 m total length. Two of us (MR and RH) are preparing a 

 detailed description of the postcranial skeleton of Styracosaurus albertensis as well as a 

 redescription of the type skull for future publication. 



Here we provide, in as detailed a format as practical, a photographic atlas of the postcranial skeleton 

 of the holotype (CMN 344), as well as of a number of previously unpublished images of isolated 

 cranial material from bone beds in Dinosaur Park, Alberta. The atlas is arranged by anatomical 

 "unit" (vertebral column, ribs, pectoral girdle and limb, pelvic girdle and limb, manus and pes, and 

 fragmentary skull material). The extent to which elements have been restored is indicated when it is 

 not evident from the photographs. 



The type skull of Styracosaurus albertensis was collected by C. H. Sternberg during the summer of 

 1913 and described later the same year (Lambe 1913). In 1935, a field crew from the Royal Ontario 

 Museum (ROM) returned to the same quarry, and recovered a mandible, and a well preserved, 

 largely complete postcranial skeleton that clearly belongs to the same individual. After some 

 negotiation, the ROM agreed to an exchange in 1955, permitting this material to be reunited with the 

 type skull. A skeletal mount was quickly assembled. As was customary at the time, the skeleton was 

 supported on a heavy steel armature, and missing bones were fabricated in plaster painted to match 

 the real bones. The skeleton has served well as a display piece, but the mounting technique has made 

 an accurate, detailed description impractical. In 2003, the skeleton was disassembled in preparation 

 for remounting as part of a new exhibit. This has provided a unique opportunity to describe the 

 postcranial skeleton of Styracosaurus albertensis. 



Considerable damage to the specimen occurred during the original mounting process. The vertebral 

 centra were drilled out and the entire ventral portions of the eleventh thoracic and second caudal 

 centra were destroyed to accommodate the armature. Some welds were done with the bones in place, 

 seriously scorching several bones. It was necessary to break some vertebrae to free them from the 

 original armature. The bones were consolidated with Acryloid (B 72), and missing portions 

 reconstructed conservatively in plaster. The plaster was then painted in a colour that contrasts 

 sufficiently with that of the bone to permit the reconstructed areas to be identified easily. 



Styracosaurus albertensis is restricted to the upper portion of the Dinosaur Park Formation of Alberta, 

 Canada (Ryan and Evans 2005). With the exception of a single subadult-sized skeleton (TMP 89.97.1) 

 from southern Alberta, all known material has been collected in Dinosaur Provincial Park (DPP). In 

 addition to the holotype (CMN 344), this taxon is represented by numerous elements collected from 

 one multigeneric bone bed (BB 42) that is composed of approximately 40% Styracosaurus material, 

 and isolated parietal spikes collected from throughout the park. Despite a number of anecdotal reports 

 of other Styracosaurus bone beds in DPP, none are known at the time of this writing. Numerous 

 individual elements and at least one partial skeleton (AMNH 5372, originally described as S. parksi' 

 Brown and Schlaikjer 1937), have been collected from DPP but unless the material includes a 

 diagnostic parietal spike it can not be unequivocally referred to Styracosaurus. 



