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Homotherium
Homotherium
serum & cubs by Paleoartist Mark Hallet
Homotherium was
about the size of a lion, but some of its physical characteristics are rather unusual. The forelegs were elongated, while
the hind quarters were rather squat with feet perhaps partially plantigrade, causing the back to slope towards the short tail.
This gave the Homotherium a hyena-like appearance.
Certain features of the hindlimbs indicate that this cat was moderately capable of leaping. The pelvic region, including the
sacral vertebrae, were bear-like, as was the short tail composed of 13 vertebrae — about half the number in long-tailed
cats.
Compared to some other machairodonts, like Smilodon or Megantereon, Homotherium had relatively shorter
upper canines, but they were flat, serrated and longer than those of any living cat. The incisors and lower canines formed
a powerful puncturing and gripping device. Among living cats, only the tiger has such large incisors, which aid in lifting
and carrying prey. The molars of Homotherium were rather weak and not adapted for bone crushing.
The skull was longer than in Smilodon and had a well-developed crest, where muscles
were attached to power the lower jaw. This jaw had down-turned forward flanges to protect the scimitars. Its large canine
teeth were crenulated and designed for slashing rather than purely stabbing. It also have an elongated neck, giving
it great flexibilty in turning its head for slashing its prey.
The unusually large, square nasal
opening, like that of the cheetah (Acinonyx jubatus), presumably allowed quicker oxygen intake, which aided in rapid
running and in cooling the brain. As in the cheetah, too, the brain's visual cortex
was large and complex, emphasizing the scimitar cat's ability to see well and function in the day, rather than the night,
as in most cats. There is also some evidence that it had a reduced ability to retract its claws. All these cheetah-like
qualities suggest that Homotherium hunted open areas, probably in a pack or pride structure, and was a good runner.
It was heavy, so it probably couldn't reach the speed of a modern cheetah.
During oil prospecting
activities SE of Caracus, Venezuela, the first fossils of homotherium were
discovered. The 1.8 million year old fossils were found along with those of panthers, wolves, camels, condors, ducks,
and horses. Best of all, about six homotherium remains were excavated along with a complete skull. This animal
has never before been seen in South America and proves that homotherium and
larger saber-tooth cats shared the same habitat.
Previously, the range included only Africa, North America, and Eurasia.
Homotherium shared its range with true sabertoothed cats, panthers, horses, mammoths, rhinoceros, elephants,
and dire wolves.
Enough elephant, mammoth, and rhino fossils have been found along with Homotherium to suggest that they fed on these
tough-skinned animals. The end of the megafauna possibly | |
Megantereon
model by Paleocraft
Megantereon
Megantereon was built long the lines of a heavy modern jaguar. It had stocky forelimbs with the lower half
of these forelimbs lion-sized. It had large neck muscles designed to power a devastating bite. The elongated upper canines
were protected by flanges at the mandible.
There has been quite a debate over the number of subspecies
due to the size differences of Megantereon throughout the world. The largest specimens with an estimated body weight
of 198 - 330 lbs. (average 260 lbs) are known from India. Medium sized forms of Megantereon are known from
other parts of Eurasia and the Pliocene of North America. The smallest forms from Africa
und the lower Pleistocene of Europe have been estimated to only 132-154 lbs.
However, other sources estimated Megantereon from the European lower Pleistocene at 220-352 lbs.
The animal has been described as having a heavy jaguar-type build but the size of a leopard. Because ony one complete
skeleton has been found (France), not much can be said about how Megantereon lived.
Megantereon probably first appeared in the early Pliocene roughly 4.5 million years ago in North America. About 3-3.5
Million years ago it is firmly recorded also from Africa and Eurasia. At the end of the Pliocene it evolved into the larger
Smilodon in
North America, while it survived in the Old World until the middle Pleistocene. The youngest remains from east Africa are about 1.5 million years old. In southern
Africa the genus is recorded from Elandsfontein, a site dated to around 700,000-400,000 years old. Remains from Untermaßfeld
show that Megantereon lived until 900,000 years ago in Europe. In Asia it may have survived until 500,000 years ago,
as it is recorded together with Homo erectus at the famous site of
Zho-Khou-Dien in China. The only full skeleton was found in Senéze, France. So far, the fossil fragments have been found
only in Africa, North America, and Eurasia.
Megantereon could
not simply bit its prey as the long, sabre-teeth are not strong enough to leave buried inside a struggling prey animal.
The teeth would break off. It is possible that Megantereon bit their prey and then allowed it to bleed to death,
but then they would have to protect that animal from other predators. Those predators would have included Homotherium, hyenas, dire wolves,
and saber-toothed cats. It is now generally thought that Megantereon,
like other saber-toothed cats, used its long saber teeth to deliver a killing throat bite, severing most of the major nerves
and blood vessels. While the teeth would still risk damage, the prey animal would be killed quickly enough that any struggles
would be feeble at best. Chances are they dined on Homo erectus (soft and chewy!) and other human
species.
Xenosmilus
hunting pair by paleoartist Mark Hallett
Xenosmilus
In 1983, a strange new sabertooth cat was discovered in the Haile limestone quarries of Alachua County, Florida by amateur fossil
hunters. Named xenosmilus hodsonae, the find had several surprises. The partial skeletons were found to
have the short, broad upper canines of the scimitar cats (like homotherium) and the short legged build of the larger dirk
toothed cats (like smilodon). Furthermore, all 24 teeth - including the 3 1/2 inch fangs -on are serrated.
The cat had a mouth full of steak knives! In fact, xenosmilus means "strange knife." (I thought I'd throw
that in because I had one person ask me if it was named after Xena: Warrior Princess!)
Roughly lion-sized, xenosmilus was more robust and muscular than the average smilodon species. It was a massive, stocky animal,
though not as large as smilodon populator. Several skeletons of peccaries were found in the cave deposits along
with a cat, possibly the xenosmilus' prey. The cave where the two specimens were found is considered to be the cats'
possible lair.
It is unusual to find a new species of Pleistocene predator like this and so far no one knows how widespread xenosmilus
were. Other North American sabertooths such as smilodon fatalis and smilodon californicus have left
many fossils - at least enough to give us an idea of range, dna lineage, and possible population. More information
about this powerful predator may be published soon. Virginia Naples of Northern Illinois University is studying the
million year old fossils. It is not yet known how long the species lasted. It could be that xenosmilus hodsonae
died off around a million years ago, allowing the rise of the other smilodon species.
I
saw a great replica of a xenosmilus hodsonae skull on the Bone Clones site. The teeth aren't as long as a smilodon's,
but they're massive! I would not be surprised to learn that xenosmilus hunted larger game than peccaries. Scientists
now favor the theory that the sabertooth cats used their impressive dental cutlery to slice
up prey rather than stab them. The stresses from the muscles left on the skulls support this theory. Xenosmilus
and other smilodons most likely held down their prey and slashed throats and bellies to kill. The prey would very quickly
die from blood loss or having its wind pipe severed.
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