INTRODUCTION TO MAMMALIAN PALEONTOLOGY 



25 



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Figure 18. — Outlines of the body form of the perissodactyls, drawn to the same scale 



The largest known member o( each family is selected for comparison. The smallest known stem forms of each family are illustrated 



in Chapter X. The animals are grouped according to their natural relationships, as indicated especially by the pattern of the 



molar teeth, as follows: 

 Bhinocerotoid group: A, Mclamynodon; family Amynodontidae; graviportal; aquatic; lower Oligocene. B, Hyracodon, family 



Hyracodontidae; cursorial; middle Oligocene. C, Ceratotherium simum; living white rhinoceros; family Rhinocerotidae; 



graviportal. 

 Tapiroid group: D, Tapirus terresiris; existing tapir; family Tapiridae; mediportal. 

 Hippoid group: E, Palaeotherium; family Palaeotheriidae; lower Eocene; mediportal. F, Equus pTzewalskii; existing horse; family 



Equidae; cursorial. 

 Chalicotheroid group: (?, MoTopus; family Chalicotheriidae; clawed perissodactyl; lower Miocene. 

 Titanotheroid group: B, Brontotherium platyceras; family Brontotheriidae; graviportal; lower Oligocene. 



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