HRDLi(^KA] SKELETAL EEMAINS OF EARLY MAN 347 



until a new discovery at Monte Hermoso attracted to it the attention 

 of Ameghino. Through Lehmann-Nitsche Ameghino borrowed the 

 specimen, studied it in detail, and published a description of it in 

 his memoir on the Tetraprothomo, identifying the bone with that 

 particular hypothetic genus of man's precursors. 



At the same time a study of the atlas was undertaken and pub- 

 lished by Lehmann-Nitsche/ who in turn attributed it, to ''a Tertiary 

 primate of Monte Hermoso, the Homo neogseus." 



Sometime during the earl}^ years of the present century Carlos 

 Amegliino discovered in the same barranca of Monte Hermoso a 

 peculiar bone, which eventually was referred to a supposed ancient 

 parental form of man. It was a portion of the fossil femur of a being 

 which F. Amegliino identified as a very ancient forerunner of man, 

 the Tetraprothomo argentinus. 



It was this specimen which excited interest in the Monte Hermoso 

 atlas and which is responsible for the establishment of the new genus 

 of Tertiary (Miocene) Primates or " precursors." 



THE REPORTED FEATURES OF THE ATLAS 



"This bone," according to Ameghino,^ '^does not belong to the 

 genus Homo, but on the other hand it approximates so closely to the 

 atlas of man that it doubtless comes from a form wliich was man's 

 precursor, and this could have been no other than the Tetraprothomo." 



As to the relatively considerable size of the bone, "comparisons 

 have shown that other nonarboreal mammals which present a femur 

 of approximately the same dimensions as the Tetraprothomo, have 

 an atlas as large or even larger than the latter. It is also to be borne 

 in mind that the femur of the Tetraprothomo indicates a body pro- 

 portionately stouter than that of man, so that such a being had also 

 a proportionately larger atlas. To this it should be added that some 

 results of an examination of the bone demonstrate independently of 

 the preceding consideration that it must have supported a skull 

 proportionately larger than that of man, from which it is inferred 

 that the atlas also must have been of proportionately greater size. 

 Furthermore, if a correspondence in size is estabhshed between the 

 atlas of a young chimpanzee of only 56 cm. in height, the atlas which 

 I suppose to be that of Tetraprothomo — a being that accorchng to 

 the femur should have reached the stature of 1.05 to 1.10 m., and 

 the atlas of a man of medium stature, it will readily be seen that the 

 fossil atlas of Monte Hermoso corresponds perfectl}^ with the height 

 and corpulency of the Tetraprothomo argentinus. . . . 



"Of course, the possibility that the two pieces, the femur and the 

 atlas, may pertain to two animals specifically and even generically 



' Nouvelles recherches, etc., p. 386 et seq. 

 3 Tetraprothomo, etc. , p. 1 74 et seq. 



