page_title: Spiclypeus
section_title: Paleobiology
hierarchical_section_title: Spiclypeus / Paleobiology
caption_attribution_description: Teeth of Spiclypeus shipporum gen et sp. nov. (CMN 57081). (A) Left maxillary teeth in lateral view; (B) right dentary teeth in lateral view. (C) microwear on the 23rd right dentary tooth showing common dorsodistally-ventromesially oriented scratches; (D) microwear on the 13th right dentary tooth showing less common dorsomesially-ventrodistally oriented scratches.
context_page_description: Spiclypeus is an extinct genus of chasmosaurine ceratopsian dinosaur known from the Late Cretaceous Judith River Formation of Montana, United States.
context_section_description: The type specimen of Spiclypeus appears to have sustained a significant infection in its frill, hypothesized by the authors to have been due to an injury inflicted by a rival of its own species. However, more evidence is needed to determine the cause of the infection. Both the left and right squamosal had received longitudinal injuries. In itself it is not exceptional that adult individuals developed holes in their squamosals, due to bone resorption at an advanced age. However, the perforations in the shield of the Spiclypeus holotype are different in having a parallel orientation and being located close to the frill edge. It was concluded that they were probably the result of intraspecific combat, the brow horns of an opponent having pierced the shield bone.
   
  Another, much more serious, infection was present in the left humerus. The entire lower half of the bone was diseased. Most of the lower joint surface must have been dysfunctional, a large abscess having largely eaten away the condyles. The bone had been reworked in reaction, rotating the joint over 90° from its normal orientation. In the middle of the shaft a deep drainage canal had developed, through which the pus ran out. Extensive remodelling of the bone shows that the infection had not been immediately lethal and was perhaps the result of a less virulent tuberculosis or fungus. The upper part of the humerus also was pathological, showing a large arthritic bone mass.
  Examination of the specimen's bones also indicates that this specimen was a mature individual at least ten years of age as there were no signs of on-going rapid growth associated with juvenile ceratopsians.
  The calfbone was sawed to determine the number of "lines of arrested growth" that are usually interpreted as annual growth lines. Seven of these LAGs are present and probably a minimum number of three lines had been obfuscated by later growth processes, resulting in the minimum age estimate of ten years. That the holotype individual had reached a relatively advanced age despite the severe infections, reflects the generally robust ceratopsid build.
caption: Teeth and microwear
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