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least 50 features unite the family Ceratopsidae as a monophyletic clade.
The large Neoceratopsians are only known from
|The heads of the post-Protoceratops ceratopsians are enormous. Even without the frill, the head is never less than 1/3 the length of the back (Tyrannosaurus is the only other dinosaur which approaches this ratio) and in Pentaceratops the head length is actually greater than the back length. Most had either two long brow horns and a short nose horn, or two short brow horns and a long nose horn. The horns were probably covered with keratin in life. The neck vertebrae were often fused to help support the weight of the head. There are two subfamilies: Chasmosaurinae and Centrosaurinae (Lambert, 1990, Fastovsky, 1996).|
|In the Chasmosaurinae, the squamosal bones were long. In Triceratops, “three horn face”, the skull was 1/3 body length. The humerus indicates that posture might have been slightly sprawling while footprints suggest that walked upright. Based on skull variations, there is disagreement regarding the number of Triceratops species that should be recognized. “Lumpers” feel that there were only 1 or 2 variable species while “splitters” may recognize as many as 16 different species.|
| In the Centrosaurinae, the squamosal bones
are short. Pachyrhinosaurus possessed a large, rough bone ridge from nose to
eye. This species lived in NW North