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STL Science Center
14 August 2013
The Big Frill
Holotype designated by HF Osborn, 1923
Measuring approximately 10 feet from the anterior of the premaxilla to the posterior end of the parietosquamosal frill, Pentaceratops had a head about as long as the largest known adult male lions; the largest known measured 12 ft, but many have been recorded around 10ft long including their tails. The horns of Pentaceratops were rather large, as we have seen and discussed previously. Technically Pentaceratops, though being called a five horned dinosaur, has only three horns. The protuberances along the cheek are epijugal extensions and are actually only extensions of the cheeks of the dinosaur. Likewise, the "horns" at the top of the frill are epiparietal extensions of bone and are, themselves, also only protuberances of bone and not true horns. The remainder of the skull is fairly typical of a ceratopsian dinosaur with the exception of the overall size. The nasal horn swings forward and up to a point and then begins to angle posteriorly at the apex. The orbital horns also follow the gentle forward curving but instead curve extremely anteriorly at the tips rather than posteriorly. The teeth are pretty much what we expect to see in a ceratopsian dinosaur as is the "beak" that makes up the majority of the premaxilla.