H. F. OSBORN — MAMMALIAN PALÆONTOLOGY 93 
tohippus, which still apparently is most nearly ancestral to Æquus, we 
find as contemporaries, the browsing, forest-living Hypohippus (Plate X), 
and the grazing and highly cursorial Neohipparion (Plate XI). À com- 
parison of the phylogeny of the Camelidæ (Fig. 5) published by Worr- 
Modern Fauna, Higher Placental Radiation. 

 ARTIODACTYLA ci PERISSODACTILA  CARNIVORA RODE 
A 
OSCIDEA x _EDENT EE SA 
Bison nus /Antilo-/ Odocoileus 3 Gbcr Arvlcola | 
RECENT Oribos kpra/ Cervus Alces + p MUR Castor ec 
IPLEISTOGENE Es RUES 773 CORRE SE 
Palygs ygèuus Fa «7 fi Machacrodus Casorsides 7 
VE |° anis Félis 
CZ AA Te = Frhphoden f Es elurodon  Canis \Eucastor 
ele AN Pre Me et Amphicyon Ft 
VE ee c Machaerodus 

Hoploph éneus 
Daphaenus 
2. 
ic Dinictis 
S RS 
y Sinopa 
Vulpavus ,f a rrigfe lis 
f / Mesony 123 
Trigono- 
nl lesles 
Pantolambäa £ il 2 Chriacrs 
L enorycles Arclocyôn 
Peript tychus fioclaenus Meniscotherium Onychotectes Trüsodon 
Archaic RU Lower Placental Radiation. 

Fire. 2 
Extinction of the lower placental radiation of the Cretaceous, and sudden introduction 
of the higher placental radiation of the Tertiary. 
The orders Amblypoda, Condylarthra, Edentata, Creodonta, and earlier Primates 
disappear in North America. The comparatively modern Rodentia, Carnivora, Perisso- 
dactyla, Artiodactyla, and Proboscidea suddenly appear without known ancestors in the 
Lower Tertiary, No connections have thus far been traced between this older, archaic 
fauna and the newer fauna. 
MAN'in 1898onthemonophyletic basis with that published by MATTHEW? 
in 1904 on the polyphyletic basis, shows the rapid progress which has 
been made in the demonstration of the polyphyletic law. Similar results 
are apparent from our preliminary studies of the Proboscidea in Ame- 
1 The Extinct Camelidæ. Bull. Amer. Mus. Nat. Hist., Vol. x, 1898, pp. 93-142. 
? Notice of two New Oligocene Camels. Bull. Amer. Mus. Nat. Hist., Vol. xx, 1904, 
pp. 211-215. 
