THE ANCESTRY OF DOMESTICATED CATTLE. 
189 
fications which may be correlated with the incoming of grasses as a 
dominant feature of the landscape (Woodward, 1898). 
The even-toed Ungulata (Artiodactyla) had their chief develop- 
ment in Europe, and after the Eocene period there was a great variety 
of forms. The ruminating Artiodactyla became vastly expanded 
and diversified. They were plastic, adaptable, and eventually 
migrated to all the continents except Australia, but perhaps did not 
reach North America until the Miocene period, at which time they 
were far advanced toward the specialized forms found in the pres- 
ent era. In the Miocene of Europe and southern India remains have 
been found of deerlike antelopes that w^ere formerly thought to be 
the lineal descendants of earlier forms of the Tragulidse. Some 
paleontologists, however, do not think that the Tragulidse are in a 
direct line of bovide ancestry.^ The Miocene antelopes referred to 
above, in the opinion of some paleontologists, mark the first appear- 
ance of the Bovidse, which includes sheep, goats, musk oxen, and 
antelopes, as well as cattle. It is the youngest and most specialized 
family of hoofed animals, having reached their best development 
only during the present geological period. Members of the family 
have been found in all parts of the globe except South America and 
Australia. In North America it is represented by the bison, musk 
ox, mountain sheep, mountain goat, and a few allied fossil forms. 
Remains found in Alaska indicate that some of these species ma}^ 
have migrated from Asia in comparatively recent times. Africa 
appears to be the center of distribution, although their original home 
may have been in Asia. The Cervidse, or deer family, is closely 
allied to the Bovidse, but they have solid horns, which branch and 
are shed annually, Avhile the Bovi'dse have persistent, unbranched 
horns, with a body horn core which is surrounded by a horn sheath 
that grows continuously from the base. Antilocapra^ an antelope of 
western North America, known as the pronghorn, is a connecting 
link between the two families. Its horns are branched and the horn 
sheath, but not the horn core, is deciduous. Other characteristics 
of the family Bovidse are described by Lydekker as follows : 
No members of the family, either living or extinct, possess npper canine 
teeth, or tusks, which are frequently so strongly developed in the deer tribe 
(especially when antlers are wanting) ; and in this respect the hollow-horneil 
are clearly more specialized than the antlered ruminants. Very rarely do 
they show those tufts and glands on the lower part of the hind logs which 
form such a characteristic feature in many of the deer. 
Further evidence of the specialization or high grade of the family is afforded 
by the fact that the lower ends of the metacarpal and metatarsal bones, which 
persist in so many of the deer, have invariably disappeared. Then, again, the 
lateral toes are very generally represented merely by the lateral hoofs, although 
in certain cases some small nodules of bone within tliem represent the skeleton 
' For ii discussion of tliis subjoct s(>o (Jrej;ory. 
