Name:
Archaeotherium
(Ancient beast).
Phonetic: Ar-kee-o-fee-re-um.
Named By: Joseph Leidy - 1850.
Synonyms: Megachoerus.
Classification: Chordata, Mammalia,
Artiodactyla, Entelodontidae.
Species: A. mortoni (type),
A.
altidens, A. coarctatum, A. lemleyi, A. marshi, A.
minimus, A. palustris, A. potens, A. ramosus, A.
trippensis.
Diet: Carnivore/Possibly omnivore.
Size: 2 meters long, 1.2 meters tall at the
shoulder.
Known locations: Canada & USA.
Time period: Bartonian of the Eocene through to the
Chattian of the Oligocene.
Fossil representation: Multiple specimens.
Fist
named
in 1850, Archaeotherium remains one of the best
represented
entelodonts
in the fossil record. Archaeotherium
is one of the
earlier entelodonts and lived in North America at a time when the
landscape was occupied by primitive horses, camels and rhinos and
the only real predatory competition it faced were creodonts like
Hyaenodon.
As
with other entelodonts,
Archaeotherium had enlarged neural spines on its
forward dorsal
vertebrae that allowed support for more powerful neck muscles, which
in turn supported the oversized skull. This made Archaeotherium
tallest and bulkiest at its fore quarters where its centre of balance
would have been. This also would have made Archaeotherium
surprisingly nimble on its feet as it would be able to pivot around on
the spot rather than having to step forwards or back out to move.
As
with other entelodonts,
the skull of Archaeotherium was long with wide
cheek bones. The jaws
could open incredibly wide which suggests that Archaeotherium
may have
frequently closed them around other animals, perhaps even other
members of its species in things like dominance contests. The large
canines at the front of the mouth would have been potent weapons that
could have quite easily punctured a cranium. It is also likely that
the forward canine teeth were used as tools for tearing off and picking
up pieces of food that were then tossed to the back teeth with a flick
of the head. Here the sharper premolars could cut and crush food into
smaller pieces that allowed for more efficient digestion.
Reconstructions
and studies
of the brain have indicated that while Archaeotherium
did not have a
high level of reasoning (meaning it would have followed set patterns
of behaviour regardless of the situation), it did have a strongly
developed olfactory area. Combined with long nasal passages from the
longer skull, this would have allowed Archaeotherium
to conduct much
more detailed sampling of the air to detect scents of things that were
both far off and perhaps obscured from view. This is similar to
modern pigs which are considered to have some of the most sophisticated
olfactory abilities in the animal kingdom.
While
smell was the primary
sense that Archaeotherium relied upon, it would
have also had good
eye sight. Forward facing eyes would have granted Archaeotherium
stereoscopic vision that would have allowed it to gauge distances
between itself and where it wanted to be. This would have been of
vital importance when Archaeotherium had to deal
with another animal,
as it would allow it judge when and how far to move to time its
strikes.
Archaeotherium
has done a lot
to increase our understanding of the entelodonts, but here it is not
its bones but its foot prints that have revealed clues. At the
Toadstool Geologic Park in Nebraska there are several sets of
fossil footprints from many different animals. One set is of an
ancient rhinoceros that shows that the living animal suddenly went from
casually walking to running at what appears to tie in with the onset of
the detection of an incoming predator. Another set of tracks that run
parallel to the rhinoceros tracks suggests that a creodont like
Hyaenodon was stalking the rhino. A third set of
tracks from an
entelodont are also present, but these have a different approach in
that they maintain a zigzag pattern across the ground in the direction
of the rhinoceros prints. Obviously the shortest and fastest route
between two locations is the most direct, and zigzagging towards
something is the antithesis to this principal.
However
no one ever said that
the entelodonts was the one chasing this rhino. The zigzag pattern of
footprints strongly suggests that the entelodonts was not chasing
anything, but was simply going through the motions of a search
pattern. By constantly changing direction the entelodont would pick
up scents on the wind for everything from the animals, to fresh
droppings, to even the smell of blood from a fresh kill. As such
the entelodont was probably waiting for another predator to expend
its energy upon making a kill and then zeroing in on the source of the
smell of blood so that it could then use its large body and immensely
powerful jaws to intimidate the other predator into giving up its
kill. We cannot of course be certain if Archaeotherium
was the exact
genus of entelodont that left the footprints, but the location and
age of the trackway does fit in within the range of Archaeotherium.
At
up to two metres long and
over a meter tall at the shoulder Archaeotherium
would have been a
powerful animal, certainly capable of incapacitating a human had the
two lived in the same time period. Despite this however,
Archaeotherium was tiny when compared to genera
like Entelodon
and Daeodon.