AET. 9 A NEW DINOSAUR FROM WYOMING GILMORE 



The ossification illustrated in Plate 4, Figure 1, is quite certainly 

 an ornamental dermal bone having a compressed upper extremity 

 whose edge is serrated with toothed denticles. That it was in con- 

 tact with another of perhaps similar shape is indicated by a sutural 

 surface at one end. The broken basal portion shows that the striation 

 of the bone radiates from a focal point near the lowermost pointed 

 end. Precisely the same type of structure is to be observed in the 

 bone filling the supratemporal opening of the T. vyyomingensis skull, 

 and for that reason I am of the opinion that this fragment represents 

 a dermal ornament of a Troodon skull. If these deductions are cor- 

 rect it shows the presence of a type of ornamentation unknown in the 

 earlier Troodonts. 



The second fragmentary piece, Plate 4, Figure 2, shows a similar 

 radiating structure, but as yet I am unable to hazard a guess as to 

 what part of the animal it may represent. The bone is especially 

 dense and heavy and the external side is peculiarly roughened. 



A fragment (pi. 5, fig. 1), U.S.N.M. No. 8795, included in a small 

 lot of miscellaneous dinosaur armor plates collected by Charles 

 H. Sternberg, in Niobrara County, Wyo., is quite certainly a portion 

 of the squamosal of a Troodont dinosaur. This is indicated not 

 only by the thick, rounded protuberances of the dorsal surface but 

 also by the deep suture at one end, a feature that is peculiarly char- 

 acteristic of the cranial elements of the Troodont skull. 



These fragmentary parts, briefly described, give evidence of at 

 least two individuals beside the type, and no doubt others will now 

 be recognized among the miscellaneous bones from this formation in 

 other collections. 



NOTE ON TROODON FORMOSUS LEIDY 



The above genus and species were established by Leidy,* on the 

 crown of a single tooth from the Judith Kiver formation of Mon- 

 tana. In the years that have elapsed since this first discovery 

 a few other detached teeth have been found in this same formation. 

 These constitute the only known materials referable to the present 

 species. Recently in looking over some fragmentary dinosaurian 

 specimens in the paleontological collections of the National Museum, 

 I came across a fragmentary portion of a skull that was at once 

 recognized as pertaining to the genus Troodon. (See pi. 5, fig. 2.) 

 This specimen was collected by J. B. Hatcher, July 7, 1888, from 

 the Judith River beds on Cow Island, Mont., a place not far 

 removed from the type locality. It would therefore seem fair to 

 infer that it belongs to the species T. formosus Leidy. If this assign- 

 ment is correct it furnishes the first information on this species 

 other than from teeth. 



* Proc. Acad. Nat. Sci. PhUadelphia, tx>1. 8. p. 72, 18.56. 



