STL Science Center

STL Science Center

24 December 2011

Looking at What May Not Exist

Monoclonius may not exist, we said as much yesterday. However, it is clear that the artist's conceptions, overall, would place this dinosaur almost solely into the Centrosaurus family and we know that there are those that feel that Monoclonius may be a female or juvenile Styracosaurus as much as it may have been its own animal.The name Monoclonius came from its tooth growth, having nothing to do with a single horn because the original type specimen did no even have a horn it was so incomplete. There is evidence for all of the cases that have been made for this animal being Styracosaurus and/or Centrosaurus specimens of different genders or ages. The evidence for Monoclonius being a sample of Chasmosaurus and/or Brachyceratops, to me, is not as straight forward, though that of course does not make it wrong, it just means I have more research to do for myself.

©Hal Robins
An alternative without the "tear" in the frill is equally viable
for the same reasons
 The case for a Centrosaurus line up of Monoclonius' remains makes sense based on the frills often found with Monoclonius which, coincidentally, are typically included in the artist renditions as they are here in this Hal Robins illustration. The markings on the frill are wonderful, but it is the top center portion of the frill which calls out as a Centrosaurus trait. The frill of Centrosaurus is just as large as any other Certaopsian dinosaur's frill, but at the top of the center of the frill on a Centrosaurus we see the remarkably torn appearance of the frill with horns facing into the torn area as well as down from the bottom of it pointing toward the face of the animal. This is what gives us the evidence that a Monoclonius, along with other evidence I assure you as I am being exceedingly simplistic in this analysis, is a younger Centrosaurus. There are other skeletal clues as well, though these clues are very important as the frill could certainly age from the above depiction to that of a Centrosaurus very easily.

 One person I am very anxious to get a hold of, and have been for quite a while now, has been Keiji Terakoshi. One of the reasons is to get official permission from him to use his artwork, the other being to congratulate him on his publications like this book sample below. While it is all in Japanese it puts all three of our questioned species, for today at least, together in one simple and easy place. Monoclonius is pictured at the top of the picture while Styracosaurus and Centrosaurus appear in the center and right on the bottom, respectively. Styracosaurus juvenile, we can see, is a little more of a stretch as it would require a considerable growth spurt in the frill. While not something that is not to be excluded from thought, it is not as probable as the growth of the Centrosaur frill. However, Peter Dodson has in the past put forth the idea that Monoclonius may have been a Styracosaurus gender role, being the female of the gender. This lack of ornamentation in females is seen all over the extant animal world in birds especially, but also in mammals and reptiles and fish as well. This is an interesting debate, and I hope to see some good evidence from the "professionals" as I continue to research so I can share it with you.
©Keiji Terakoshi

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