Fig. 1.
 MACN A52-617, holotype oi Archaeohyrax patagonicus, left side of skull, viewed as right (adapted from
 Ameghino, 1897…
       
          
        typotheres) were members of the endemic South
 American group Notoungulata. George Gaylord
 Simpson's views on the…
       
          
        present within the lateral depressions on the sym-
 physis, almost directly beneath the canine.
 The premolars are all heavily…
       
          
        nation of the members (e.g., Archaeohegetotheria,
 Hegetoarchaeohyracoidea) could also be used.
 Some combination of these…
       
          
        mostly late Oligocene Deseadan SALMA. Filling
 a niche that presumably was similar to that of the
 hypsodont archaeohyracids,…