Lull — Restoration of the Horned Dinosaur Diceratops. l 421 



supraorbital horns meeting the enemy at the same moment of 

 impact. The frill now becomes of greater protective value 

 instead of affording leverage merely for the muscles of the 

 neck. 



Diceratops exhibits the extreme of development of this style 

 of warfare, for the supraorbital horns are the sole aggressive 

 weapons while the widely expanded frill served admirably to 

 withstand the shock of the adversary's horns. "We have here 

 a precise analogy with the knight of old tilting with his spear 

 and shield. 



The skull of Diceratops shows the horns to be very erect, 

 much more so than in Triceratops, so that the head would have 

 to be carried much lower in charging than in the latter genus 

 and the horns through relatively short are extremely powerful. 

 I have indicated a callosity, the last vestige of a horn, over the 

 nasals, for they still remain very highly arched and evidently 

 bore some of the impact of the adversary's blow. The eyes 

 were set in deep thick-rimmed sockets which look directly out- 

 ward, evidently limiting the forward range of vision, but afford- 

 ing ample protection to these highly necessary organs. 



If one will turn to Hatcher's figure of the Diceratops skull 

 (Plate XIII, figures 1 and 2), he will notice in the frill several 

 apertures which Hatcher has called "fenestrae." Two of 

 these are through the squamosal portion of the frill, one on 

 either side, and one through the parietal.* They are irregular 

 in size and in position, and while the Judith River types and 

 Torosaurus among the Laramie forms have parietal fenestras, 

 they are large and symmetrical, and there is no instance of squa- 

 mosal fenestras in any known genus of Ceratopsia. If the 

 author's conception of the final function of the frill is correct, 

 there would be no reason for the development of apertures 

 through it, which would only tend to weaken it and mar its 

 usefulness. It seems vastly more -probable that these are " old 

 dints of deep wounds" received in combat. None of them, 

 not even the great one on the left, were necessarily fatal, as 

 they all seem to be through the free portion of the frill, 

 and, while the bone was destroyed, the horny or leathery integ- 

 ument may have grown again over the gap as indicated in 

 the model. The edge of the apertures are healed, showing 

 that the animal lived for some time after the injuries were 

 received. 



I have represented the gape of the mouth with much less 



* Mr. C. W. Gilmore, who prepared the type specimen of Diceratops, is by 

 no means sure of the "parietal fenestra." There was no bone adhering to 

 the matrix at that point so he left the opening through the frill for want of 

 evidence to the contrary. The bone forming the margin of the left squamosal 

 aperture is decidedly pathologic. 



