Monthly Archives: October 2015
The Transvaal Caves in South Africa, popularly known as “The Cradle of Humankind”, are justly famous as the source of some of the most important hominin fossils in existence, but they have also yielded a few remarkable fossils of sabretooths. One of these is the holotype skull of Dinofelis piveteaui. This beautiful fossil, found at the cave of Kromdraai, was described as early as 1955 by Rosalie Ewer, and she already noted its marked sabretooth features: the dentition included a pair of flattened, flesh-piercing uper canines, an impressive row of enlarged incisors, and huge, blade-like carnassials for processing meat with enormous efficiency. Coupled with a specialized mastoid zone for insertion of powerful neck muscles, these adaptations allowed D. piveteaui to dispatch large prey with a proper sabretooth killing bite, causing massive blood loss and a quick death.
Several years ago I had the privilege to study that magnificent fossil at the Transvaal Museum, and my first impression was contradictory: all the sabre-tooth adaptations were there to be clearly seen, but the nice preservation of the Kromdraai skull shows something else: in spite of these “machairodontine” adpatations, the general morphology of the skull was remarkably feline: The muzzle was short (due in large part to the short diastemata, or empty spaces between the canines and premolar teeth), the cranium was broad across the zygomatic arches, the orbits were large and forward-looking and the dorsal outline of the skull was gently convex.
All in all, the geometry of this animal’s skull resembled that of a jaguar more than that of a “classic” sabretooth like Megantereon or Homotherium, with their long muzzles, narrow faces and straight dorsal outlines.Also, and in spite of their flattened shape, the upper canines were so short that barely the very tips, if anything, would show when the cat closed its mouth (as in the case of the clouded leopard, which has longer canines than any other modern cat and still they are mostly hidden by the upper lips).
One consequence of this conservative, feline geometry of the skull, is that the life appearance of the head of D. piveteaui would also be quite cat-like, especially when seen from the front. When relaxed, its warm and fuzzy look would barely let us imagine what a killing machine we had in front of us.
If we could see the animal baring its teeth during a fight with a rival cat, or with a bloody muzzle while dispatching its victim, we would get a more balanced view of the so-called false sabretooth. But that is a different story…
I find it a bit annoying when any kind of animals are given the name “false-something”. It is as if such animals were somehow inferior or secondary to the “true” or “original” ones. Such an unfair treatment has been given to a group of sabretooth cats often called “false sabretooths”, and more properly known as the metailurins (technically a tribe within the felid subfamily machairodontinae). Among the metailurins, the genus Dinofelis was the latest to evolve, and they are most often referred to with that offending common name.
But there is nothing false about Dinofelis. As far as we know, these animals, like all metailurins, were true members of the subfamily Machairodontinae -that is, they were proper sabretooth cats. Back in the late Miocene, when no member of the feline subfamily had as yet grown any larger than a lynx, metailurins had reached full cougar size, and they had also evolved the flattened upper canines and enlarged carnassial teeth that are the hallmarks of machairodonts. Over the millions of years they gave rise to Dinofelis, which grew to full jaguar size, and the last species, called Dinofelis piveteaui, developed remarkably flattened sabres, huge carnassials, a set of protruding, impressive incisors, and a specialized mastoid area in the skull for the insertion of powerful neck muscles that aided in the specialized type of killing bite shared by all sabretooths.
In Eurasia, Dinofelis was the dominant big cat in the early Pliocene, when the climate was warm and humid and huge forests covered much of the continent, but the more open environments of the late Pliocene onwards gave the advantage to more specialized sabretooth cats: Megantereon and Homotherium.
In Africa, however, Dinofelis managed not only to stand its ground in the face of the other sabretooth cats, it actually thrived and evolved into a diversity of species. In fact, Dinofelis appears to have survived in that continent until a later date than the other machairodontines.
One of the key advantages of Dinofelis was the fact that, being less specialized than Homotherium or Megantereon, it was more flexible and better able to cope with changes in environmental conditions and prey availability. Even the relatively specialized Dinofelis piveteaui was a “jack of all trades” compared to its more extreme neighbours. It was larger than Megantereon and thus more powerful, but at the same time it retained better climbing capabilities than Homotherium. It could retreat into forests and survive on smaller prey, because its relatively short upper canines were less prone to breakage when hitting bone than in the case of the “classic” sabretooths.
So, rather than a “false sabretooth” what we see in Dinofelis is a true survivor.
Here we see Dinofelis piveteaui walking casually in a savannah envoronment, under the careful monitoring of a few horses. But, judging from its body proportions, this animal would be equally at home in the gallery woodlands and even in relatively dense forests.
There were other species of Dinofelis which evolved in a somewhat different direction, developing less “sabretoothed” dentitions than other metailurins and actually resembling our pantherine cats to a remarkable degree. We will look at those fascinating animals in upcoming posts.
If you want to know more about the metailurins, their diversity, and how they fit in the world of sabretooths, get my book, “Sabertooth”!
Long before the true sabretooth cats evolved, the strange nimravids ruled the stark plains of the Spanish Oligocene, and among the largest of the nimravids was Dinailurictis. One fossil site that provides an intriguing glimpse into that lost world is Carracosa, in Cuenca province.
Data from the fossil site indicate that the climate was dry and seasonal, and the animals that inhabited this region would have looked quite unfamiliar to us. Dinailurictis, with a body mass of around 130 kg, was clearly a top predator, and in this reconstruction we see it having just caught a pig-like ungulate, Methriotherium. Slightly larger ungulates, like Eggysodon (a lightly built relative of the rhinos, seen in the background) would also be among its potential prey, while the hare-sized Cainotherium would be in most cases too small and agile to be worth chasing. Crocodiles were common in Europe during these hot times, making it more dangerous for animals to quench their thirst.
The fossil record of late Oligocene mammalian faunas is extremely patchy in Spain, so a fossil site like Carrascosa is extremely valuable. The site was discovered decades ago during the works for the construction of a water transfer from the Tagus to the Segura river basin, and it remains virtually our only window into the environments and the strange animals that lived there and then.
Looking back at the feline encounters we had during this year’s edition of “Drawing the Big Cats”, perhaps the most endearing moment was to meet again our beloved Machaba leopard female in the Khwai River area of the Okavango, an to find that she had a new, incredibly cute cub.
Our little leopard family was resting in a secluded site, among shrubs and fallen branches, so that while trying to film and photograph them the vegetation made it annoyingly difficult to get a clean shot. But as a sketcher I find precisely those elements to be useful as suggestions of possible compositions. One day when I plan a scene for an illustration I may make tweaks and rearrange things here and there. But with only pencil and paper and a few minutes to make my sketch, I don´t judge what I see, just let the scene soak in.
There is a delightful disorder in nature that is always more rich and spontaneous than our efforts to create order. Of course I need to arrange things according to a plan when I design an illustration, but sketching quickly and faithfully is the best way to remain mentally flexible. Letting nature be our teacher is the best way to make sure that we learn something new everyday!
Here is the “finished” sketch. Just as the environment provides the necessary shelter for the cats in the wild, the apparently chaotic elements of the vegetation are no less important than the cats themselves in this quick drawing
In my previous post I commented on how it could take you months to make sense of what you observed during just a few days out in the African bush. Well, that was an understatement. It can be years before something you saw in the wild finally seems to click in your “scheme of things”. Or may be it is just that I am a slow learner.
A few years ago I was awed to watch a cheetah killing a gezelle in the Ndutu area of Tanzania. I had seen this drama many times in documentaries, but seeing it in front of my eyes not only was breathtaking: it confirmed the strange sensation that these cats are a bit awkward about handling their prey. Of course there was nothing awkward about the way this amazing cheetah mother caught the gazelle in the blink of an eye, dispatched it in a few minutes, and provided a most welcome meal for its hungry cubs. And yet…
Back home I compared the footage of the cheetah kill with that of a leopard kill I had witnessed the previous year in Samburu reserve, Kenya. Still something felt un-catlike in the way the cheetah killed, but what could it be? In fact, the cheetah’s killing bite is extremely efficient and takes the adaptation of felines for strength and precision one step further. A short muzzle and extremely powerful jaw-closing muscles imply that the cat can sustain its bite for many minutes until the prey dies of asphyxiation. Actually the leopard kill I saw was less orthodox in that the cat was biting at the muzzle, not the throat of its prey. And yet…
More recently I went through the footage again, and suddenly I realized what was bothering me. The way the cheetah was holding its prey made it look like it didn´t know what to do with its paws. In fact it was just resting its front paws on top of the prey, much as a dog will do when possessively chewing a large bone. In contrast, the leopard I filmed at Samburu held its prey’s head firmly between its paws, a fitting embrace for such a “kiss of death”. Actually, this difference made a lot of sense from an anatomical point of view -and gives me further insights into sabretooth behaviour.
“What do sabretooths have to do with this?”, you may ask. Let me explain. The key difference between the cheetah and the other big cats in terms of how they handle their prey is the morphology of their forelimb bones, especially the elbow and wrist. A few million years ago, the cheetah’s ancestors had paws more like those of a leopard or a cougar. But as the cheetah lineage became more adapted for speed, the elbow lost part of its ability to rotate the forearm, and the wrist and hand became more narrow and less flexible. The forelimb of the cheetah was becoming better adapted to move exclusively in the vertical plane, while losing extra weight in the form of muscles that rotate the paw… in other words, it was becoming more similar to that of a dog than to that of its own feline relatives. As a result, the cheetah can’t use its paws as efficiently as the leopard for holding its prey during the killing bite. That is one more reason why the cheetah sticks to relatively small prey. And that is one reason why the cheetah is a much poorer climber than the leopard is!
Concerning the sabretooths, there was also a diversity of forelimb morphologies among them. Robust smilodontins like Smilodon or Megantereon had powerful and well-muscled fore-paws with fearsome retractable claws, well able to rotate in any direction and to hold large prey immobilized in any position. But members of the genus Homotherium had lost part of those adaptations in order to become more efficient runners. The wrist of Homotherium was much narrower than those of smilodontins, more restricted to rotation in the vertical plane, and its claws were smaller and less fully retractable, except for the huge dewclaw -something not unlike what we see in the cheetah.
Of course Homotherium was no cheetah. It was a lion-sized sabretooth cat with enormously strong forelimbs, whose mere body weight could help it control prey animals the size of a horse. But still the way it handled its prey would be somehow different to how the hyperrobust Smilodon did. Careful observation of the behaviour of modern big cats can still throw new light on how to reconstruct their extinct relatives.
It’s been quite some time since my last post, and one reason has been the need to digest the experiences of our latest “Drawing the Big Cats” safari to Botswana. What you see in the African wilderness during just a few days can keep your mind busy for months, trying to make sense of your observations. Our friends at “Elephant Trails” have once more done an amazing job at taking us where the action is, and now it is my turn to share some bits. But before, a little flashback.
In earlier posts I discussed the way big cats use their teeth to feed, and what implications it has for the way the sabretooth cats would eat. Such apparently technical considerations are important not only for inferring behavior, but also to reconstruct the sabretooths’ life appearance. As I’ve mentioned before, some old hypotheses about the way sabretooths dealt with their food led to rather shocking reconstructions. Some experts claimed that the sabretooths would need very long mouths, in a sort of monstrous “ear to ear” smile, because if they had normal feline lips their huge upper canines would simply get in the way of food items. Watching a few wildlife documentaries made me suspect that such theories were likely wrong, then my colleagues and me went on to dissect some felines and make inferences with a more tangible biological basis. We published our results quite a few years ago, but there was still a lot to learn.
This year we have had plenty of opportunity to see the big cats gorging themselves. This may sound unremarkable but it is not. In wildlife films you see the predators hunting and eating all the time, but that is an effect of the way they “filter” hundreds of hours of observation. In real life when you drive through the savanna it is the herbivores that you see eating, munching leaves and grasses almost without pause (much as you would see if you could make a Pleistocene safari, I’m afraid!). But the predators you rarely meet, to start with, and when you come across them they are usually just resting or casually making their way from point A to point B. Hunting? Hardly ever. Eating? Only rarely so. Frustrating as this may be, it makes you appreciate even the briefest glimpse of the big cats. So, it is not every day that you see a group of adolescent lions gorging on the carcass of a hippo; or two male lions eating a young buffalo in one sitting right in front of your eyes, reducing the plump calf to little more than skin and bones; or a leopard consuming a huge catfish it just fished… as we did in this trip. It was a long and comprehensive lesson in big cat table manners, and we sat in front of the feline banquets long enough to see all the details that the wildlife documentaries consider too slow and boring to show. But we were not there just to be entertained: we intended to learn.
My preliminary conclusions: just like the tissues in their lips and mouth, the cats’ feeding behavior is flexible, more so than we imagine. Our tabby at home grabs its cat-chow rather mechanically; after all it’s just a mound of little biscuits. But dealing with the carcass of a large animal is a completely different matter.
Surprisingly, the first tool our Botswana lion used to attack his buffalo carcass was his rough tongue. The vigorous licking wets the fur and makes the skin more tender and ready for the biting. Then comes the first carnassial bite, when the cat uses its scissor-like cheek teeth to tear open the prey’s skin. Once the carcass is open, the cat bites at the different portions in different ways, as a butcher would use different knives for different cuts. Now it cuts straight with the incisors, then it applies the side of its mouth for another carnassial biting, then it just uses its whole mouth to detach and gulp a large piece of meat.
These observations enrich my previous concepts about how sabertooths would eat. Admittedly, some of the things lions do with their food the sabretooths probably could not do. Yes, their sabres would get in the way if they tried to bite in this or that particular way. But most of the biting styles deployed during the feline meals we saw were perfectly feasible even with the huge upper canines of a fully grown Smilodon. Such observations are not totally new. Blaire Van Valkenburgh made a careful field study of carcass consumption several years ago which accounted for many of these eating modalities (you can see her article here). But for me as a paleoartist, watching and recording these things first hand is like finding a treasure.
In fact, many sabertooth species had an advantage for this style of biting: their proportionally longer necks would allow them to pull even farther. One of these days I need to draw Smilodon fatalis doing just that on a bison carcass at Rancho la Brea… I am sure it happened many times!
Reality can provide the answers we need, but often they come from where we least expect them, and sabretooth feeding habits are no exception. Many readers may remember Jean-Jacques Annaud’s classic film “Quest for Fire”. Those interested in the making of the film will remember that the sabretooths appearing in a key sequence were in fact trained lions (the days of creating furry creatures with digital FX were still faaaar in the future), provided with a set of prosthetic upper canines. But there is one detail less widely known: unlike the elephants that were disguised as woolly mammoths for the film, who really hated their costumes, the lions were not too uncomfortable with their prosthetics, so the animals’ trainers decided not to remove them between filming sessions, thus saving the lions and themselves some uncomfortable handling. And the lions did eat quite normally while wearing their draculesque fake fangs. Not a problem for them! It is a pity that back when that film was made there were no such things as our DVD “making-of” specials. Otherwise, we might have some valuable footage of those lions demonstrating how real life is always more flexible than some scientist’s minds…