Suppose and Assume

©Nobu Tamura

Taking after Paul, who made the estimates of body length and size, we can assume that the specimen he used, NMC 8547 (Canadian Museum of Nature), represents a postcranial skeleton of Anchiceratops. Assuming it does, we have a vertebral column of 74 bones. The neck is short in comparison to many other dinosaurs, but is considered long for a ceratopsian, containing 10 vertebrae. There are 13 dorsal and 12 sacral vertebrae composing the trunk and pelvis of the animal. The tail is also considered short at 39 individual elements, some of these are also found in the pelvic region though and are not dedicated tail bones. The average known chasmosaur (the family of Anchiceratops) is built different with 12 dorsal and 10 sacral forming the trunk and pelvis and up to 46 caudal vertebrae forming the end of the pelvis and tail. Ceratopsians, like many other animals, have fused vertebrae in the pelvis (known as the synsacrum) as well. It has been suggested the synsacrum of this specimen was oriented posteriorly compared to other chasmosaurs and that the trunk was not necessarily of a different length, just arranged differently. The pelvis is actually considered to be elongate also. The forelimbs are robust, another trait we consider normal for ceratopsians. It can probably assumed that the hindlimbs are also rather robust.

The frill we briefly mentioned already. The frill is covered with "epi" bones that are named for the bones from which they originate (or that they sit on, if that is more accurate) and include episquamosal, epiparietal, and epoccipital. To be completely accurate in describing them, these are osteoderms, meaning that they developed from bony deposits of the skin and not in the same manner as the squamosal, parietal, and occipital that they are all attached to. Anchiceratops also possessed bony knobs medially located on the parietosquamosal frill. These are varied in size and shape on individual animals. They are probably entirely unique to each individual rather than being an artifact of imperfect preservation.