. Bulletin of the Department of Geology. Geology. 1917] Stock: Skull and Dentition of Nothrotherium 143 Planops, according to Scott, "the premaxillae were evidently large, the facets for them upon the maxillaries being of uncommon size, while the median notch for the spines is a characteristically deep and narrow ;18 In Megalonyx jeffersoni Leidy describes1" the pre- maxillaries as "simple, oblong, quadrilateral plates, a little more than two inches in depth, and three quarters of an inch in ; Owing to the slenderness of the muzzle, the anterior aspect of the
. Bulletin of the Department of Geology. Geology. 1917] Stock: Skull and Dentition of Nothrotherium 143 Planops, according to Scott, "the premaxillae were evidently large, the facets for them upon the maxillaries being of uncommon size, while the median notch for the spines is a characteristically deep and narrow ;18 In Megalonyx jeffersoni Leidy describes1" the pre- maxillaries as "simple, oblong, quadrilateral plates, a little more than two inches in depth, and three quarters of an inch in ; Owing to the slenderness of the muzzle, the anterior aspect of the skull of Nothrotherium is decidedly unlike that in Megalonyx. In M. jeffersoni, according to Leidy, "The end of the face is relatively narrower and higher than in Mylodon; and in outline is more ver- tically oblong quadrilateral, with the upper margin convex and the sides nearly ;-0 In Nothrotherium where the first or canini-. Fijr. 3. Nothrotherium shastense Sinclair. Cranium, no. 208 M. H. S. A., inferior view, X %. Raneho La Brea Beds, California. form tooth is absent, the anterior end of the skull is nearly round or oval. The external narial opening is relatively wide transversely as contrasted with the height. The lateral walls show no indication of notching as in Megatherium. With the disappearance of the canini- form tooth in Nothrotherium the depression of the lateral wall of the maxillary anterior to 1VP becomes nearly obsolete. This depression is better developed in Hapalops and is very pronounced in Megalonyx. The palate (fig. 3) anterior to may be approximately twice as wide as between the tooth-rows. The lateral borders of the eden- tulous portion of the palate may be nearly straight as in no. 632 or is Scott, W. B., Kept. Prin. Univ. Exp. Patag., 1896-1899, vol. 5, p. 322, 1904. io Leidy, J., op. cit., p. 11, 1855. 20 Leidy, J., Please note that these images are extracted from scanned page images that may have been digitally enhanced for
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