EARLY SOUTH AMERICANS 291 
low tide. In sinking the additional pit, the fragment 
of a human skull was found by a workman. The 
fragment was given to Mr Junor, who was in charge of 
the works, and by him it was presented to the National 
Museum, Buenos Aires. Thirteen years later, Dr 
Ameghino published an account of this fragment. The 
deep stratum of the Pampean formation from which it 
was extracted he regarded as early Pliocene in date of 
formation, and the fragment he conceived to be part of 
a small and peculiar skull of an ancient and extinct 
genus of humanity, which he named Diprothomo. 
There is no reason why the specimen should be rejected 
as worthless because of its defective history. On the 
other hand, there are the very soundest grounds for 
rejecting Ameghino's conclusions as regards the age of 
the stratum and the nature of the cranial fragment. 
Geologists refuse to regard the stratum in which the 
fragment was fdlind as older than Pleistocene, and 
anatomists are unanimous in regarding the cranial 
fragment as representing the frontal bone and part of 
the parietals of a human skull which in size and shape 
must have been very similar to skulls of American 
Indians.^ From what has been shown in this and in 
the previous chapter, there is no reason for being 
surprised at the discovery of a fossil skull, showing 
American-Indian features, in a deposit of Pleistocene age. 
Ameghino's Diprothomo thus represents a man of the 
American-Indian type living in the Argentine during 
Pleistocene times. 
Ameghino's Miocene form of man — Tetraprothomo — 
had also to go by the board. Only the atlas and the 
thigh bone of this strange evolutionary form were dis- 
covered. The thigh bone proved to be that of an extinct 
carnivorous animal of the cat genus, and as large as a 
puma ; but the atlas was human. Unfortunately, the 
antiquity of the atlas may very well be called in question. 
1 See Professor Schwalbe's " Studien zur Morphologie der siid- 
amerikanischen Primatenformen," Zeitsch. fiir Morph. und Anthrop.^ 
1910, vol. xiii. pp. 209-258. 
