Smilodon
Name: Smilodon
(Knife
Tooth).
Phonetic: Smie-lo-don.
Named By: Peter Wilhelm Lund - 1842.
Classification: Chordata, Mammalia, Carnivora,
Felidae, Machairodontinae.
Species: S. populator (type), S.
fatalis,
S. gracilis.
Type: Carnivore.
Size: The largest species, S. populator was
around 2.6 meters long.
Known locations: Throughout North and South America.
Time period: Throughout the Pleistocene, till the
very early Holocene.
Fossil representation: Hundreds of individual
specimens.
Whenever
you
hear someone mention a ‘Sabre Toothed Tiger’, what they are
really talking about, whether they realise it themselves or not, is
Smilodon. This is because Smilodon
does not belong to the same cat
family as Tigers, which belong to the Pantherinae group. As a
member of the Machairodontinae, a more acceptable generic name for
Smilodon is 'Sabre toothed cat'. This is not
to be pedantic;
it's just about being factually correct so that people do not learn
the wrong information.
Smilodon
has a very wide
expanse in the fossil record with the earliest species S.
gracilis
being known from the early Pleistocene till the Ionian stage about
five-hundred-thousand years ago. Not only is S. gracilis
the
earliest species of Smilodon, it is also the
smallest with weight
estimates between 55 to a 100Kg.
S.
fatalis
is more
intermediate in size with estimates of 160-280Kg. Its entry in the
fossil record incorporates the final three sixths of Smilodon's
temporal
range 1.6 million years ago near the start of Calabrian, till the
early Holocene ten-thousand years ago. This overlaps the existence of
S.gracilis by a little over one million years.
The
largest and last species
of Smilodon is S. populator,
known in the fossil record from the
upper part of the Calabrian till the early Holocene ten thousand years
ago. Study of Smilodon remains also indicates
that for a period of
five-hundred-thousand years between the Calabrian and Ionian stages,
all three species would have existed and been active at the same time
as one another.
One
interesting hunting
theory is that Smilodon would lurk in the tree
canopy waiting for a
prey animal to walk underneath. Smilodon would
then drop out of the
trees and onto the animals back, sinking its teeth into it is neck
before it even knew what had hit it. This is especially plausible for
S. gracilis, as if its size estimates of
55-100 Kg are
correct, it would be in roughly the same weight class as a modern
leopard, a big cat which is known to spend a lot of time in trees.
However,
S. populator was
a much larger species of Smilodon, and as such
would need either
larger or more prey. With maximum weight estimates approaching half a
metric ton , its large weight would also restrict its ability to
drop from the trees. Although it may still have been able to drop
from rocks which would be better able to support its weight, this
still may have been a too passive method of hunting to support itself
as a larger body would require more food to fuel it.
For this reason it is highly likely it would at least on occasion
switch to a different method of finding food.
Large
numbers of Smilodon
have been recovered from the La Brea tar pits in California. In fact
the recovered remains are in the hundreds, with an unknown number
still waiting to be found. Smilodon would have
been lured to this
predator trap on the false promise of free food as other animals had
become stuck and began struggling and calling out in distress. Many
carnivorous animals, not just Smilodon, ended
up getting stuck
themselves as indicated by the vast numbers and types of remains.
This
indicates that Smilodon
like other predators was not above scavenging, either at La Brea or
other locations. This does not mean that Smilodon
was just a
scavenger, in fact cats from the largest Tigers to the smallest
domestic house cats are all active predators, which is why even well
fed pets will still kill birds and bring them back to their owners.
While
direct fossil evidence
has not been found, Smilodon are sometimes
envisioned as being pack
hunters in a similar fashion to modern day lions. Although perhaps
not the fastest of runners, two or three Smilodon
jumping upon a
large prey item could have used their combined strength and body
weights to wrestle their prey to the ground. Once restrained, one
of the Smilodon would then be able to finish the
prey off with a bite
to the neck, severing the arteries and closing the windpipe.
Although
the large 'sabre
teeth' of Smilodon appear to be devastating
weapons, they were
actually very fragile for canine teeth. Just as you can use a lever
to magnify force to lift an object, the oversized teeth would also
have been susceptible to magnified forces. Smilodon
also had weaker
jaw muscles than many other large cats that had smaller teeth,
perhaps as an adaptation to reduce exposure to potentially teeth
breaking stresses. However, weaker muscles would also allow Smilodon
to open its mouth wider, and as we shall see, that is a vital
adaptation.
A
key feature of the jaws
is the enormously wide gape. Compared to one of today’s lion's that
can open their mouths to 60 degrees, Smilodon
could double this
by opening its mouth to 120 degrees. Although impressive on
paper, this is actually a very necessary adaption if it were to get
full use of its teeth without also being handicapped by them.
Considering that the teeth were up to 28centimetres long, the
lower jaw would barely clear the bottom of the teeth if it could only
open by 60 degrees.
Smilodon
may have also been a
delicate eater due to the two larger teeth getting in the way of the
smaller canine teeth. This would mean that Smilodon
had to take
smaller bites from a carcass as the large teeth were not suitable for
tearing off large chunks. They may however have helped to hold bones
in place while Smilodon chewed on them with its
rear teeth, although the weaker jaw muscles probably meant that Smilodon
did not spend much time trying to crack open bones.
Returning
to the above
proposal of pack hunting in Smilodon, there are
two areas of support
for this theory. The first is the paleopathology of Smilodon
remains. Many of these specimens show signs of injuries to bones and
the areas of muscle attachment that are so serious they would take
weeks, and even months to heal, and would be enough to prevent a
Smilodon from actively hunting. In solitary
creatures these wounds
would mean that the animal could not hunt and would actually starve to
death, but many of the Smilodon specimens show
that they healed.
This means that the injured Smilodon had to get
its food from
somewhere while it recovered, and one explanation is that it was
supported and fed by other members of the group. This behaviour can
be observed in prides of lions today.
A
second piece of support
references a study of African carnivore reactions to the sounds of
distressed animals. When the investigative team played back the
sounds, they noticed that social carnivores would approach the
sounds, whereas solitary ones would typically give them a wide
birth. This suggests that when smaller carnivores hear the distress
calls, they know that not only are larger carnivores coming to
investigate, they are coming in their numbers too. A smaller
carnivore is smart enough to know that if it goes to an area where
large predators are not just present but numerous, it will likely end
up being killed and eaten too.
This
scenario is quite
plausible for the La Brea Tar Pits and the parallels that can be drawn
between this study and the fossil evidence of la Brea, gives a very
good indication to the social interaction of not just Smilodon,
but
other ancient predators such as dire
wolves.
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