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Monoclonius recurvicornis..a new generic name



Monoclomius recurvicornis is one of the forgotten species named by Cope (based 
on 3 horn, a braincase, and an occipital condylum); however, the generic name 
is wrong: this animal was another kind of animal.
The "M." recurvicornis is often regarded as an indeterminate ceratopsid, but 
the fragmentary holotype have some truly intriguing character present in no 
other ceratopsid. Although the specimen is a subadult, the shape and dimension 
of the horns are totally different from any other centrosaurine or 
chasmosaurine. The suprahorbital horn are 210 mm high, completely erect, and 
slighty procurved, totally different from Chasmosaurus (the only chasmosaurine 
with short supraorbital horn), and only superficially similar to the new 
Montana centrosaurine. Moreover, the orbital horn appear to be born from a 
separate center of ossification (this feature would be unique in ceratopsian 
kingdom). The nasal horn is a small version to that of Einiosaurus, and like 
other subadult centrosaurine, the horn is split in two halves. In front of 
right eyes there is an unespected formation: a small procurved hornlet; the 
left side is no preserved, so one can?t tell if that horn was pathologic. 
Unfortunately the frill is no preserved.
This combination of character (moderately erect suprahorbital horn, medium 
sized, strongly procurved nasal horn and Maybe an extra pair of small hornlets 
in the frontal) are not comparable to any known ceratopsid taxa, and probably 
are diagnostic at generic level.
This animal should be renamed under another generic name, ?cause is totally 
different from Monoclonius sensu stricto (indeterminate centrosaurines based on 
subadult of Centrosaurus and Styracosaurus). However, the available material is 
scrappy, and his relation with other ceratopsid remain unclear (without a 
parietal or squamosal anyone can tell if this critter was a basal centrosaurine 
or was member of the clade Chasmosaurus + Pentaceratops).

Lukas Panzarin





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