Page 137 - Prehistoric Animals

Thy-La-Kos-Milus

Thylacosmilus

Thylacosmilus (pouch knife) is an extinct genus of sabre-toothed
metatherian* mammals that roamed the earth from the Late Miocene
to the Pliocene about 10 million to 3 million years ago. It was around
1.5 meters long and weighed in at an estimated 150kg. After he named
the species in 1933, Elmer S. Riggs, commented, after he’d studied and
named T. atrox and T. lentis, this is, ‘one of the most unique flesh-
eating mammals of all times’.

Thylacosmilus may have looked like a sabre-toothed cat but it
was not a cat; it was a marsupial. It had a pouch, similar to the modern
day Kangaroo, where it would nurture its young. However, it did have a
powerful cat-like body, with short muscular legs and a large head with
jaws lined with an array of teeth that have proven a bit controversial.
Its huge canine teeth were flat like a blade not rectangular like those of
the sabre-toothed cat. From its lower jaw hung a bony sheath where
these long canines would slip into when its jaws were closed. It had no
upper incisors; teeth essential for scraping and ripping flesh from the
bone. Its rows of flat molar teeth showed no signs of wear; wear being
an indication of a predator gnawing or crushing bone.

At first sight Thylacosmilus looks like your typical aggressive sa-
bre-tooth predator. Its teeth, however, tell a different story. Coupled
with jaws that lacked a strong bite, many believe its long flat canine
teeth were not strong enough to deliver that fatal blow and then help
drag its prey to the ground. They were more suited, they say, for just
slicing through and pulling off soft flesh. With the absence of upper in-
cisors, for scraping and removing flesh from the bone, and the pristine
condition of its molars, it’s generally accepted Thylacosmilus avoided
the bony parts of it prey and was strictly a soft flesh eater. In fact, some
think it was just an everyday scavenger.

No one knows what animals Thylacosmilus preyed on, or how it
pursued and caught its prey. Its short muscular legs suggest it was not a
fast mover; maybe, capable of only short bursts of speed. That would
make it a stalker; lying in wait for the opportunity to pounce. Whatever
the truth is, Thylacosmilus was around for a long time. Its demise how-
ever, many believe, started when the two continents of North and South
America eventually joined. This joining allowed more adapt and aggres-
sive predators into Thylacosmilus hunting grounds. So rather than a
sudden disappearance, caused by some cataclysmic event, Thylacosmi-
lus, deprived of its prey, simply faded into extinction.

* Metatheria (Wikipedia)
is a mammalian clade that includes all mammals more closely related
to marsupials than to placentals.