Fig. S. Upper Oligocene-Lower 

 Miocene Exposures of "Western 

 Nebraska. 



A Lower Miocene (Harrison, 

 Rosebud) of Western Nebraska 

 and South Dakota. 



B Lower Miocene, resting on Brule, 

 generalized section at Agate, west- 

 ern Nebraska. 



Id 



Z 

 Id 



O 

 O 



UJ 



o 

 _1 



Merycoch cerus 



Parahippus 

 Mo r opus 



Merycochcerus 

 (abundant and 



characteristic) 

 ? Merychyus 

 Bias torn eryx 

 Oxydacty/us 

 Testudo 

 Amphicyon 

 (primitive stage) 



LEVEL OF AGATE SPRING 



fossil _ quarry Diceratherium 

 Moropus 

 D/nohyus 



Deemonelix 



Zieds " ? Merychyus 



(primitive stage) 



Promerycochcerus 

 vantasse/ensis 



Parahippus 



Promerycochcerus 

 carriheri 



UJ 



Z 

 Id 



O 



o 



CD 

 _) 



o 



(C 

 Id 



CL 

 Q- 

 D 



Porcupine butte 

 Volcanic ash layer 



Meryeo ch cerus 

 zone 



Blastomeryx 

 Parahippus 

 Cynodesmus 

 Phlaocyon 

 Oligubunis 

 Megalictis 

 Oxydacty/us 

 Desmat.'yus 

 Protomeryx 

 Merycochcerus 

 Merychyus (abundant) 

 Aelurocyon 

 Arctoryctis 

 Entoptychus 

 Lepus 



Promerycochcerus 

 (very abundant 

 and characteristic) 

 Dicera theriurn 

 £iotherium 

 Steneofiber 

 Hypertragulus 

 Parahippus (small sp) 

 Leptauchenia 

 (near base) 



Nimravus 

 Moropus 

 Dinohyus 

 Mesoreodon 



Diceratherium 



Leptauchenia 

 ?Mesoreodon 



BRULE ~=-^^^^^^^=Jsep(xzucheriia. zone - 



C Lower Miocene (Rosebud) resting on Brule (Oligocene), 

 near Porcupine Butte, South Dakota. 



D Section of the Lower Miocene west of Harrison, Nebraska. 



Leptauchenia 



14 



