. Bulletin - American Museum of Natural History. Natural history; Science. 146 Bulletin American Museum of Natural History. [Vol. XXII, (Nos. 10851 and 10855). Other specimens in the 1903 collection referred to this species are a fragment of lower jaw containing teeth, p2 to m= (No. 10862), and two fragments of young jaws containing the milk molars (Nos. 10854 and 10860). The type tooth, with a few other isolated upper teeth, reported by Leidy from the Little White River locahty, have hitherto represented all that was known of this species. Cope considered it synonymous with Protohippus placid
. Bulletin - American Museum of Natural History. Natural history; Science. 146 Bulletin American Museum of Natural History. [Vol. XXII, (Nos. 10851 and 10855). Other specimens in the 1903 collection referred to this species are a fragment of lower jaw containing teeth, p2 to m= (No. 10862), and two fragments of young jaws containing the milk molars (Nos. 10854 and 10860). The type tooth, with a few other isolated upper teeth, reported by Leidy from the Little White River locahty, have hitherto represented all that was known of this species. Cope considered it synonymous with Protohippus placidus,' but, though the teeth are only slightly larger than those of P. placidus and have in common comparatively long and shghtly curved crowns, they cannot be referred, under the definition, to that genus. The protocone in N. gratum is free for the greater part of its length, while in P. placidus the protocone is joined to the protoconule for nearly its entire length. The new material shows other characters which make yet clearer distinctions between the two species. The protocones are usually small, and elliptical in cross-section. The enamel borders of the fossettes are a httle more deeply folded. Fig. II.—Neohipparion gratum Leidy. Upper jaw, inferior view, half natural size. No. 10863, from the Loup Fork formation. Little White River, S. Dakota. than in P. placidus. A marked difference is the presence of a single deep fold in the anterior border of the anterior fossette. This fold does not appear in any specimen of P. placidus or P. perditus, but seems to be always present in little or moderately worn teeth of all Neohipparion species. Further distinctions are shown in the skull and- lower jaws. Both the lachrymal and malar foss£e are present in skull No. 10863, but they are moderately deep and are hmited in extent. There is also a broad, shallow depression in the middle of the forehead. The palate is high-arched, especially in the anterior portion. The anterior palatal f
Size: 2841px × 879px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectscience
