NO. 7 EARLY CENOZOIC VERTEBRATES FRIES ET AL. 23 



any other described sciuravine. This is the structure of the paracone- 

 protocone crest, which is continuous rather than composed of a short, 

 oblique inner crest, and a largely independent paracone." 



Order Perissodactyla 

 Superfamily Tapirotdea 



In August 1950, John D. Edwards found, associated with the ro- 

 dent fragments, part of the right carpal and metacarpal of a right 

 forelimb, I.G.M. No. 52-4. These were sent by Fries to the U. S. 

 Geological Survey and the following report was made by G. Edward 

 Lewis : "The tapirid specimens consist of fragments, probably asso- 

 ciated and even articulated originally. The right unciform, magnum, 

 trapezoid, and fragments of metacarpals 2, 3, 4, and 5 are present. 

 They represent an animal perhaps less than a third the size of the 

 living tapir, with a relatively less splayed out, more slender, and prob- 

 ably longer forefoot. With respect to proportions, this same rela- 

 tion is also applicable between this animal and Miota pirns [Miocene 

 of North America] and Protapirus [Eocene and Oligocene of Eu- 

 rope, Oligocene of North America]. It is about 60 percent as large 

 as these two genera. In proportions and size it resembles and is 

 about 85 percent as large as Colodon [Oligocene of North America] 

 but does not show the latter's tendency toward monodactyly in the 

 third metacarpal." 



Ing. A. R. V. Arellano (1952, p. 63) sent these specimens to R. A. 

 Stirton, of the University of California, who considered the foot 

 bones very similar to those of the oreodonts of the family Merycoido- 

 dontidae. The bones were later studied by Dr. C. Lewis Gazin, of 

 the \J. S. National Museum, who spent considerable time studying 

 the specimen and stated: 'T confirm Lewis's determination of it as 

 a tapiroid foot." 



Age of fossils. — The exact geological age of the specimens is un- 

 known. The lack of any knowledge concerning the early and middle 

 Cenozoic vertebrate life of Mexico leaves the age assignment of the 

 vertebrate fossils open to question. It is not known whether the 

 vertebrate faunas of Mexico during the early and middle Cenozoic 

 were noticeably different from the faunas to the north, and espe- 

 cially whether or not some generalized forms hold on longer in Mex- 

 ico than in the north. This can be determined only by future study 

 of the deposit and its contained fossils. Wilson (1949. P- 97) makes 

 the following statement in regard to the geologic range of this sub- 

 family: "In time, the Sciuravinae are known to have ranged from 



