Monthly Archives: June 2013

Deadline approaches for joining the Botswana Big Cat Adventure

If you want to join the safari “Drawing the Big Cats with Mauricio Anton”, it is about time to get in touch with my friends at Elephant trails!

This is going to be the experience of a lifetime. We get to Botswana at the best time of the year to observe the big game animals, including the felines, against the background of what is probably the most sublime savannah landscape in Africa. We visit the Okavango  Delta, the legendary Savuti Marsh, and the spectacular Chobe River front, ending with a visit to Victoria Falls and a close-up and personal experience with lions.

SavutiHorizonjpg

After and in between our game-drives, we will share sketching sessions back at camp, and exciting discussions about big cat action and anatomy. Besides, there is an exclusive surprise for all the participants, but that will be revealed in due course!

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The safari departs on September 12 and ends on September 22. Don’t miss the opportunity to join the creative event of the year!

You can contact Mauricio Anton (info@mauricioanton.com) or Elephant trails for information about prices and details.

See you in Botswana!

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OUCH, THAT HURTS! Human-Sabertooth interaction at Dmanisi

The early Pleistocene fossil site of Dmanisi is justly famous for the abundance of hominid remains, but it is also very rich in fossils of the sabertooth cat Megantereon.  Taphonomic studies suggest that the fossil site area corresponds to what was a small peninsula in the margin of a lake during the Pleistocene, making it a good place for predators to ambush their prey. Megantereon would often kill here, and hominids soon learned that there would regularly be carcasses to steal. A solitary, medium sized cat, Megantereon would normally retreat from an aggresive, organized band of hominids, leaving its kill behind.

But now and then the patience of the cat would reach its limit. Maybe the hominids were already busy butchering the carcass, chatting among them and oblivious to danger, when the angry cat dashed from its hiding place among the bushes and quickly killed one of the hominids with a painful bite to the skull…

How do we know this episode ever took place? Well, the fact is that one of the hominid skulls from Dmanisi, labelled as D2280, happens to have two punctures in the occipital area that correspond with amazing precision with the size and separation of the tips of Megantereon‘s upper canines. Too oval in shape to be the marks of a jaguar’s conical fangs, and too small and close together to correspond to the larger sabertooth Homotherium (both felids  also lived in the area), these punctures are very reasonable evidence that Megantereon did attack this hominid. And even if the wound may not have been deadly, the fact that the hominid skull was found at the site suggests that it died shortly after the encounter (from this or other wounds), beacause the Damnisi fossils hardly suffered any post-mortem transport and correspond to creatures that died right there in the area.

The shape and position of the puncture marks in the skull allow us to infer quite a few interesting things about the behavior of Megantereon:

1.- As seen in the schematic drawing below, the punctures could only be produced with the cat biting from the front and top of the head, thus forcing the cat to open its jaws in an angle well over 90 degrees. I spent some time manipulating the casts of the hominid and felid fossils from Dmanisi and there was no other possible way to position both skulls that would result in such wounds. We already knew from the anatomy of Megantereon that it was capable of such phenomenal gape, but this is striking evidence of it happening.

2.- The absence of visible puncture wounds in the frontal area of the skull where the lower canines would have hit the bone (see the drawing below) strongly suggests that the upper canines were striking with much greater force. This fits wonderfully with the “Canine Shear-Bite” hypothesis, where the intial penetration of the sabers into the body of prey is driven by a downward pull powered by the anterior neck muscles, rather than by the jaw closing musculature. A conventional bite powered by jaw-closing muscles would result in more forceful pull of the lower canines and, in this case, would likely cause additional punctures in the skull.

Dmanisi-homo-megantereon-skulls-low-res

3.- The very presence of these punctures seems to contradict the hypothesis that sabertooths were extra-careful not to hit bone when biting at their prey, and suggests unusual behaviour. But this example does add to a series of cases from the fossil record where there are unmistakable puncture marks caused by sabers in the bones of other animals. Can you guess what is it that most of these examples have in common? Well, in most of those cases it is the bones of other predators, not prey, that bear the mark of the saber. Coincidence? Not likely.

In fact, among modern large carnivores there is a clear difference between “proper” hunting and the aggression toward other predators which are perceived as competition. The big cats rarely eat the carcasses of other predators after killing them, and the sort of body languaje they use during such confrontations suggests that a different set of emotions is triggering the aggression. This is not the cold, almost “professional” approach they show when hunting prey, it looks rather like hatred, if we can indulge in some measure of “antropomorphism”…

In the context of that non-predatory violence, targeting competitors rather than prey, it is possible that indiscriminate biting becomes more common, and the cats are less careful about avoiding bone when biting. Hell, this is not hunting, this is WAR! We see skulls and bones of sabertooths and dire wolves in Rancho la Brea tha have been clearly pierced by sabers, and there is the famous skull of Nimravus punctured by an Eusmilus skull that I pictured in an earlier post in this blog…

But then there are examples of different situations also… To learn more, look for the book “Sabertooth” in October!

An now, a VERY rough sketch made as I tried to figure out how the actual attack may have happened. That surely hurted!

megantereon-bites-homo-dmanisi-low-res

The Sabertooth’s Terrible Hook: the case of Lothagam’s cat

Sabertooth cats are justly famous for their namesake upper canine teeth, but they had another remarkable weapon of trade: an enormous dewclaw which was quite appropriate for the tasks of catching prey and keeping it motionless while the cat applied its surgically precise killing bite.

There is plenty of evidence from the fossil record about the widespread presence of this feature in different species of sabertooth cats, but perhaps the most beautiful example is the holotype skeleton of Lokotunjailurus from the fossil site of Lothagam in Kenya. This sabertooth cat was an elegant,  lightly built animal, about as tall at the shoulder as a lioness but with more slender bones and a much smaller body weight. The preservation of this specimen was so exquisite that it included a complete articulated forepaw with all the bones in place, down to the claw phalanges.

Back in 1999 I visited the National Museums of Kenya in Nairobi in order to prepare reconstructions of several species of fossil verterates from Lothagam, which would illustrate a monograph about the site and its fauna. During my visit to the museum I worked with paleontologists Lars Werdelin and Meave Leakey in the study of the fossils.

One of the advantages of working in a place like the National Museums of Kenya is that you have access to the skeletons of modern animals from their anatomy collections in order to compare and put the anatomy of fossils in perspective. A most interesting exercise was to put on the same table the bones of the forepaw of the sabertooth Lokotunjailurus, a modern lion, and a modern leopard.  Of course the most striking feature of Lokotunjailurus was its dewclaw, which was larger than that of the lion, although the latter was clearly a larger and heavier animal. But the claws of the remaining digits of Lokotunjailurus were smaller than those of the lion, and in fact they were smaller than those of the leopard, although the latter animal was much smaller than either the lion or Lokotunjailurus.

What is the meaning of such distinctive claw proportions in the sabertooth? One interesting fact to consider is that among modern cats, the cheetah  resembles the sabertooths in having a proportionally large dewclaw and small claws in the other digits.  Another meaningful similarity is that in both the cheetah and the Lothagam sabertooth, the claws other than the dewclaw are less retractable than they are in more typical cats like lions and leopards. Does this mean that Lokotunjailurus was a sprint hunter like the cheetah? not likely, because its body porportions were not those of a sprinter, but it could certainly run at moderate speeds with more endurance than a modern lion.

It seems that in sabertooths, as in the cheetah, the dewclaw was especially important in catching and restraining prey, while the remaining claws had a greater role in locomotion, giving the cat a better traction on the terrain. This makes sense because sabertooths had a longer history as ground dwelling cats -they “came down from the trees” far earlier than their feline cousins did. A less advantageous aspect of the sabertooth’s claw anatomy was that the animals, especially the close relatives of Lokotunjailurus (including Homotherium and Amphimachairodus) were less than competent climbers, a price they had to pay for their efficient terrestrial locomotion. After all, evolution and adaptation are all about compromise.

You can see a discussion of the early evolution of the sabertooths’ dewclaw in this post about Promegantereon:

https://www.facebook.com/photo.php?fbid=570239433016890&set=a.561542060553294.1073741828.551797904861043&type=1&theater

And now a drawing of the skeleton of the forepaw in Lokotunjailurus (with some bones slightly rearranged to fit their anatomical life positions), together with a reconstruction (bottom) of the appearance of the same paw in life . I have shown the paw with all claws protracted, in the position they would be while handling live prey. Claw sheaths are not bone and thus were not preserved in the fossil, but I have shown their hook-like outlines at the end of each claw phalanx.

Lokotunjailurus-forepaw-low-res

And now a reconstruction of the life appearance of Lokotunjailurus based on the Lothagam skeleton. Here the claws are in a relaxed position as they would be during the normal walk, but even so their tips are visible. When the cat was running, the claws would protrude further and contact the ground, as they do in the cheetah.

Lokotunjailurus-Life

To learn more about Lokotunjailurus and its adaptations look for the book “Sabertooth” in October!

Our Ancestors’ Love-Hate for Sabertooths

Hominids have a long story in common with sabertooth cats. The earliest members of our own zoological family were vegetarians that fitted quite nicely with the role of sabertooth prey. Not a very important prey at that, because as a source of meat ungulates have always been more important, so our early ancestors such as Ardipithecus and Australopithecus would only occasionally figure in the menu of felids like Dinofelis, Megantereon or Homotherium. Even so, their life in the African forests of the Pliocene period would be always marked by the fear of the dagger-toothed felids.

But things changed in the Pleistocene. The appearance of our own genus, Homo, meant the entrance of hominids to the carnivore guild, probably as timid scavengers at first, but with an ever more assertive attitude as they developed a more sophisticated use of stone tools and a greater body size. By the time when the species Homo erectus (or Homo ergaster, as some specialists call the African populations) appears, hominids have become a force to reckon with among African predators. The leopard-sized sabertooth Megantereon was one of the most efficient hunters of the wooded savannahs, but as a solitary cat it had little chance to defend its kills against a well organized gang of the tall, aggressive and object-throwing hominids.

Did this relationship develop into a full-fledged kleptoparasitism? This term means that one species regularly steals the food from another without any benefit to the provider. Evidence is very complex to interpret, but current views tend to support this notion. In fact, if pressure from hominids got too heavy it might even contribute to the final extinction of this felid. There is interesting evidence, nonetheless, suggesting that now and then one hominid paid his bravery with dear life during such conflicts…

Even more complex is the possible relationship between species of Homo and the larger sabertooth cat Homotherium, which not only was as big as a lion but probably had some kind of social structure.

The possible implications of the uneasy coexistence between Dinofelis, MegantereonHomotherium and our own relatives are discussed at some length in my upcoming book, “Sabertooth”. For those more technically minded, here is a link to an academic paper where we discuss in depth the coexistence between Homotherium and hominids in the Pleistocene:

http://www.mediafire.com/?35c93nyk23u3lr8

Here is a hypothetical scene where the sabertooth Megantereon whitei tries to defend its kill (a waterbuck antelope) from a gang of Homo erectus. I am sorry to say it doesn´t look good for the cat…

anuncio-homo-ergaster-megantereon