Systematic Catalogue of Vertebrata of the Eocene of New Mexico: Collected in 1874

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U.S. Government Printing Office, 1875 - 37 pages

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Page 7 - Artiodactyla, &c. The simplicity of structure resembles, on the other hand, that found in the opossum and various Insectivora, Rodentia, and Quadrumana, and in the Proboscidia, most of which have the generalized type of feet. The structure indicates that the carnivorous genera named were plantigrade — a conclusion which is in conformity with the belief already expressed, that the mammalia of the Eocene exhibit much less marked ordinal distinction than do those of the Miocene or the recent periods....
Page 6 - ... of the quadrituberculate molar but a single one, ie, the anterior external, remains. The same process may be observed in the successional modifications of the entire dentition of the jaws. The Eocene forms of carnivora frequently display more numerous sectorial teeth (such as they are) than any of the existing families.
Page 7 - ... performing the functions of life. These Eocene carnivores also (according to Cope) showed a primitive character in the tibioastragalar articulation, or " ankle-joint." " The astragalus is flat, and the applied surfaces are nearly a plane, and without the pulleyshaped character seen in existing carnivora, as dogs, cats, and, in a less degree in the bears and in other mammalia with specialized extremities, as Perissodactyla, Artiodactyla, &c. The simplicity of structure resembles, on the other...
Page 7 - In other words, the numerous types of digitigrade carnivora which have survived, are those developing but one sectorial tooth (whose earliest representative is Didymictis). The increased perfection of the sectorial has been associated with a reduction in the number of other molars, first posterior, then anterior to it. which reduction has been accompanied by an increased relative size of the sectorial. By this process concentration of the carnassial function has been gained, and increased robustness...
Page 6 - ... cutting blade. The posterior portion of the tooth does not share in this elevation, and its two tubercles are in some genera obsolete, and in others replaced by an elevation of one margin, which leans obliquely toward the middle of the crown. In Mesonyx this is represented by a median longitudinal crest. If the two tubercles of the posterior part of this tooth (which may be termed a tubercular sectorial) are elevated and acute, we have the molar of many recent and extinct Insectivora ; if the...
Page 6 - The development of the carnassial dentition has thus been accomplished, first, by an addition of an anterior cusp, and subsequently by the subtraction of the inner and posterior cusps, so that of the original tour of the quadrituberculate molar but a single one, ie, the anterior external, remains.
Page 3 - Newberry, the geologist who accompanied him, was then actively employed in his duties on the Sanitary Commission in the West. Colonel Macomb has recently transmitted to this Office Dr. Newberry's report, with its twenty-two illustrations; and I have respectfully to recommend that it be printed at the Government Printing-Office, and that 1,500 copies be furnished for the use of the Engineer Department upon the usual requisition; also, that this Office be authorized to procure the necessary copies...
Page 6 - The development of the carnassial dentitioit has thus been accomplished, first by an addition of anterior cusp, and subsequently by the subtraction of the inner and posterior cusps, so that of the original four of the quadrituberculate molar but a single one., ie, the anterior external, remains. The same process may be observed in...
Page 3 - UNITED STATES ENGINEER OFFICE, GEOGRAPHICAL EXPLORATIONS AND SURVEYS WEST OF THE ONE HUNDREDTH MERIDIAN, Washington^ DC, June 30, 1874.
Page 6 - Hymnodontidce, as is known, possess three carnassial teeth without inner tubercles. The history of this form is as yet uncertain, as it was evidently not derived from contemporary forms of the Eocene with tubercular sectorials. The development of...

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