Troodon FORMOSUS

Leidy, J., 1860, Extinct vertebrata from the Judith River and Great Lignite formations of Nebraska., Transactions of the American Philosophical Society 11, pp. 139-154 : 147-148

Troodon FORMOSUS .

In association with the remains previously described from the Judith River, Dr. Hayden discovered the tooth of a large Monitor, to which the above name has been applied. Probably aquatic like many of the living Monitors, the voracious Troodon was most likely a troublesome enemy to the peaceful plant-eating Palaeoscincus .

The fossil tooth ( figs. 53-55, plate 9 ,) bears much resemblance to one of the lateral denticles of the teeth of the great extinct shark, Carcharodon angustidens , and under other circumstances might readily have been mistaken for such.

The specimen is black and shining, and is laterally compressed, conical, and curved backwards, as observed in the Monitor ornatus . The margins of the tooth are trenchant, and strongly denticulated; the denticles possessing the same form as the crown itself. On the convex border of the tooth there are eleven denticles, and on the concave border, seven; and on both borders the points of the denticles diverge upwardly.

The broken base of the crown is elliptically trapezoidal, and is hollowed on the interior. The crown is invested with enamel, which on one side of its summit is worn off by the attrition of an opposing tooth passing it like the blades of a pair of scissors. The length of the specimen is 3 lines; its antero-posterior diameter at base, 2 lines; and its transverse diameter, 1 1/2 lines.

I have no evidence that part of or all of the vertebrae supposed to belong to Palaeoscincus , do not really appertain to Troodon . This question must be left for future investigation to determine Explanation of Figures, Plate 9.

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Figures 53—55. Tooth of Troodon formosus ; magnified three diameters.

Figure 53. Outer view.

Figure 5t. Inner view, exhibiting the enamel worn from the summit.

Figure 55. Section at the base of the specimen CHELONIA.

Figures

1-20. Trachodon mirabilis 21-48. Deinodon horridus 49-52. Palaeoscincus costatus 53-55. Troodon formosus.