There are 5 orders of ungulates which are now
The early ungulates of the Palæocene and Eocene
epochs have for a long time been grouped together in the Order
Condylarthra. This consists of several families at least two of which
are known to have given rise to modern orders of ungulates.
first ungulate, was a condylarth.
Taken as a whole the condylarths were a widespread
group. Condylarths were found throughout Eurasia, North America,
South America and Africa. Ungulates also reached Antarctica, which
had a temperate climate in the early Tertiary. Most incredibly, a
recent find of dental material in early Eocene rocks of Queensland,
Australia suggests that condylarth placental mammals were present at
is known only from a single tooth, but analysis of its structure and
enamel ultrastructure place it with the condylarths.
For a long time this order contained the solitary
Arsinoitherium . This
early Oligocene African horned creature is fascinating for numerous
reasons - its apparent isolation in the fossil record and its
convergence with the rhinoceroses and brontotheres on other
continents. Other arsinoitheres are now known from Asia Minor and the
The Embrithopoda is now considered the 'stem group'
of the Proboscidea, that is to say the ancesors of the proboscids
The desmostylians are one of the most bizarre
ungulate groups. Skulls were discovered in marine sediments long
before the skeletons, leading to the conclusion that desmostylians
were aberrant sirenians.The tusks on both jaws were reminiscent of
early proboscids, while the teeth were apparently replaced from the
back of the jaw as in sirenians and proboscids. When skeletons were
found it became obvious that desmostylians were very different from
the sea cows - they were short-tailed and had fully-formed, robust
hind and fore-limbs.They could perhaps best be described as
small-headed, buck-toothed hippopotamuses. It has been suggested that
they may have 'poled' their way along the substrate at high tide,
much in the manner of a hippopotamus 'walking' along the bottom of a
river. They probably ate seaweed, or perhaps shellfish. Recent finds
in North America suggest that desmostylians may be closer to the
Proboscidea than the Sirenia.
All but one of the desmostylians are from the Pacific
coasts of Asia and North America, where they persisted to the late
Pliocene. A single fossil from Florida helps to connect them to a
likely origin by the shores of the ancient Tethys Sea.
ORDER NOTOUNGULATA AND ORDER LITOPTERNA.
Two orders of ungulates confined entirely to South
America, where they evolved in isolation from other ungulates for
nearly 60 million years, until the Panamanian landbridge formed 2.5
million years ago.
The notoungulates included a variety of forms, some
of which looked like rhinoceroses, others like rodents and
lagomorphs, others like the peculiar perissoadactyl chalicotheres and
some had skulls like horses.
The litopterns were even more unusual. Some were very
like camels, including a bizarre creature with a proboscis called
described as "a cross between a camel and a tapir".
Perhaps the most amazing of the South American
ungulates were the litopterns of the Family Prototheriidae. These
were very horse-like indeed, and evolved singl-toed limbs 20 million
years before they appeared in horses.