Search Results for Homotherium
Paleontologists are thoroughly familiar with the shape and disposition of the teeth of the sabretooth Homotherium, and could never confuse them with those of a modern big cat. But when the animal was alive, soft tissue covered the maxilla and teeth, and obscured the differences. Obviously the proportions of the head, with a massive muzzle and a straight dorsal outline, were clearly different from those of a lion.
But if we could see Homotherium performing the “flehmen” gesture, then the depth of the differences with any modern big cat would become truly evident. During “flehmen”, cats pull back the lips in a grimace and elevate the snout, in order to allow odoriferous particles in the air to reach the vomeronasal organ, located back in the palate. They often do it in reaction to finding the odour of another cat, and they can judge, for instance, if a female is in oestrus.
But for the casual observer, the Flehmen response is a wonderful way to see the shape of the cat’s dentition, and in the case of Homotherium, it would reveal that the animal was “all incisors”. Effectively, while the incisors of a lion are relatively small and arranged in a neat row closely in front of the canines, those of Homotherium were disproportionately large and projecting in an arch. So spectacular were the incisors that the canines themselves would not impress us too much, especially compared to those of dirktooth cats like Smilodon.
In this reconstruction of Homotherium doing “Flehmen” you can see the large size of the incisors and how they porject far in front of the upper canines. In the lower jaw, the the incisors are so large that there is little difference with the lower canines.
Another advantage of the Flehmen response is that the animals keep it for several seconds while slowly moving the head sideways, thus allowing us to observe the teeth at leaisure. Artists often prefer to depict the animals in aggresive situations, where bared teeth are part of a violent encounter and where, in real life, we would only see a brief flash of the creature’s weaponry. But if I were one of the hominids that shared the environments of Pleistocene Europe with Homotherium, I would far prefer that the animal I met was doing flehmen rather than snarling in aggression. That way there would be greater chances that the impressive array of Homotherium‘s teeth wasn´t the last thing I saw in this world!
It has long been clear that Homotherium was the sabertooth genus that lasted longest in Europe, and the one that had most relevance for hominins living in that continent during the middle Pleistocene. Fossil finds from Atapuerca, for instance, showed its presence at a time when Homo heidelbergensis was well established in Spain. But the most dramatic evidence of coexistence between hominins and Homotherium arrived recently in the form of an amazing discovery at an already famous site: Schöningen.
The fossil site of Schöningen is known to archaeologists worldwide because of the miraculously preserved wooden spears found there in the late 1990s. The site yielded massive amounts of ungulate, and particularly horse remains, many of which showed clear signs of having been butchered by hominins, and the shape of the wooded spears, clearly designed to be thrown at a distance, gave clear indications as to how those horses would be hunted.
Last year, a new discovery was announced at Schöningen: several fossils of the sabretooth Homotherium had been found at the very same level (Schöningen 13 II-4) that had yielded the spears. The finds included several teeth of a young adult cat in pristine condition, and an impressive humerus bone.
Last week I had the privilege to attend a workshop that took place at the beautiful Paläon museum at Schöningen to discuss the relevance of the Homotherium finds and to place them in a truly multidisciplinary context. I was able to observe the new fossils first-hand, and the diversity of the talks and presentations at the meeting provided a kaleidoscopic perspective, and plentiful food for thought.
At 300,000 years old, these are the youngest Homotherium fossils to be found in a well-studied, stratified fossil site in Europe, and impressive as the findings are, the implications are simply phenomenal. Detailed studies will be published before too long that will change the way we see the interaction between humans and Homotherium.
At Schöningen, our extinct relatives had plenty of occasions to meet this imposing predator. Dangerous as those encounters could be, I would gladly trade myself for one of those hominins for a few days, for the chance of being face to face with Homotherium. But please, let me take with me one of those wonderful wooden spears. Just in case.
The spectacular fangs of sabertooth cats have been often seen as possible adaptations to pierce the hide of giant, thick-skinned prey such as proboscideans. But living elephants are such formidable creatures that it is difficult to accept that they would be the main targets of any mammalian predator. And yet there are pieces of evidence which clearly show that, at least in some instances, sabertooths did hunt proboscideans.
At Friesenhahn cave in Texas ( a fossil deposit of late Pleistocene age) the bones of several sabertooths of the genus Homotherium, including individuals of different ages, were found in association with those of many mammoths and mastodons. The place was in all likelihood used as a den by the cats, and the proboscidean bones show clear tooth marks, proof that the sabertooths were eating from them at the site. The proboscidean bones corresponded to animals between 2 and 4 years of age, a time when they are still of “manageable” size for the predators, but less closely vigilated by the mothers who need to concentrate in protecting their younger, more vulnerable calves.
But even at such young age, elephants make rather inconvenient prey. Even with the long and flattened canines of Homotherium, the diameter of the elephant neck is just too big and the skin too thick for an efficient killing bite to take place, so the dispatching of prey is by necessity long as it gets slowly weakened through blood loss from relatively superficial wounds. On the other hand, the sheer size and strenght of even a calf of this age makes it very difficult for a single cat to keep it pinned down to the ground. This disadvantage is made more serious by the fact that Homotherium, unlike other sabertooths, had long forelimbs with narrow wrists and small, not fully retractable claws (except for the enormous dewclaw).
The scene below shows a group of Homotherium and a young mammoth in the early Pleistocene of Southern Spain.
So, if we look at the overall anatomy of Homotherium we see that it was not an ideally built “elephant killing machine”. In terms of the ability to single-handedly wrestle down a large prey, even a lion is better equipped, but then the sharp canines of Homotherium were a real advantage to inflict nasty, debilitating wounds.
For me, there are 2 conclusions to be gained from this overview of the evidence:
First, that in order to bring down young proboscideans as the Friensenhahn cave sabertooths obviously did, hunting in a group would be a distinct advantage, and in fact it was probably a necessary condition.
Second, that since the overall body build of Homotherium was not that of a “giant slayer”, the odds are that the systematic elephant predation we see at Friesenhahn was either a local phenomenon, or a seasonal one, or both. Elsewhere and at different times of the year, there was probably a variety of prey for Homotherium to take, but my guess would be that it most often concentrated on ungulates of horse to bison size, and whenever it had to hunt individually, it would certainly go for lighter animals like horses or antelope.
So, giant slayer? potentially yes, but only under the right circumstances.
To learn more, look for the book “Sabertooth” in late october!
Leafing through folders with old drawings I found a few rough sketches for two paintings I intended to include in “The Big Cats and their Fossil Relatives” (1997). Back in those days photo references were much harder to come by and I had to relay more heavily on my clay models, which I set in the pose of the planned painting and put under a lamp to mimic the desired lighting conditions.
During the late 1980s documentary viewers around the world were awed at the athletic feats of the tigers of Ranthambore, especially the formidable male nicknamed “Genghis”, who used to charge through the shallow water in pursuit of sambar deer. It was only natural that I wished to paint a similar scene with a different cast of characters, in particular the agile, tiger-sized sabertooth Machairodus catocopis and the strange artiodactyl Procranioceras, both from the late Miocene of North America.
In my earliest sketches for this scene I showed a different prey, Syntethoceras, which looked conveniently bizarre, but then I found that it apparently did not coexist with M. catocopis in the same fossil sites.
Another sensation for wildlife documentary lovers back in the 1980s was the revelation of the intimate life of the white wolves of Ellesmere island, then filmed and photographed for the first time. Those predators chased their prey, from hares to musk oxen, in the barren expanses of the high Arctic, and in my mind the connection was made with the lightly built Beringian sabertooths of the genus Homotherium. Paleontologist Bjorn Kurtén had hypothesized that those animals would be black to match the coat color of their main prey, the woolly mammoth, but I found at least as likely that they would be white to match the winter color of their environment, just like the arctic wolves.
So I set to paint a scene with white predator and white prey inspired in those breathtaking Ellesmere images. I wanted to show my subjects under the dramatic light of the low arctic sun, and once again I had to model my creatures in clay and light them. The horns of the Dall ram were especially complex objects and I would have been at a loss to paint them without the figurine.
In this case the final painting did find its way to “The Big Cats”!.
The early Pleistocene of Africa was a time when modern species of large mammals coexisted with others that are no longer with us, creating an exciting mosaic of animal diversity. Sabertooth cats like Homotherium were still at large, but many of the animals they preyed upon were of modern type, from horses to antelopes. But now and then they would come across an elephant-like creature that had long become extinct in Europe and Asia: Deinotherium.
Deinotheres are classified, like elephants, in the order proboscidea, but they belonged in a family of their own, the Deinotheriidae, which probably diverged from the lineage of elephants very early on.
Deinotheres had elephant-like body proportions but their tusks emerged from the mandible rather than from the maxilla, and they curved downwards.
If deinotheres had tight societies like those of modern elephants, it would be very hard for predators to catch a young individual -hard, but not impossible. Even lions manage to snatch a young elephant every now and then in spite of the adults’ almost constant vigilance.
But once the elephantine prey was down, the advantage of the sabertooths over the lions would become evident. With their long, flattened and coarsely serrated upper canines homotheres would be able to pierce their prey’s though skin and even reach the blood vessels underneath. That would be good for the predators, who saved a lot of time, effort and risk, and merciful for the deinothere, who would die from massive blood loss in a couple of minutes. Lions hunting elephants, on the other hand, can take ages to finally kill their prey, who in some occasions is virtually and slowly eaten alive. Bloody as the sabertooth kill was, it would be, in a way, much cleaner than that of its modern relatives, at least when it came to thick-skinned prey.
Today the cheetah, Acinonyx jubatus is the only cat with clear adaptations for extremely fast sprint running, but in the past there were other species, more or less closely related to it, which also developed that kind of specialisation. The American cats of the genus Miracinonyx (about which I wrote in some detail in an earlier post) lived during the Pleistocene and paralleled to a remarkable degree the cursorial features of the cheetah skeleton, although none of them was quite as specialised as the true cheetah. But in the Pliocene and Pleistocene of the Old World there was an early species of the true cheetah genus Acinonyx, what we could call a cheetah with a difference. Of course I am talking about Acinonyx pardinensis, the giant cheetah known from many fossil sites from Spain to China, and which is known to have been considerably taller than the modern species. It is tempting to imagine that, having comparable adaptations for running as the modern cheetah but with absolutely longer limbs, the giant cheetah could have reached higher peak speeds, but would it?
Many years ago I had the opportunity to study casts of a partial skeleton of A. pardinensis from Perrier (France) housed at the Paris Museum of Natural History, and I was impressed by the animal’s enormous size and advanced running adaptations. The animal probably weighted about 70 kg, but its limb bones were quite elongated and so were its lumbar vertebrae, betraying a long and flexible back just as in the modern cheetah. But a detailed examination reveals some features in which the giant cheetah appears to be intermediate between the advanced morphology of the modern cheetah and that of the more “normal”, slower cats. For instance, the femur is not as strongly bowed as in A. jubatus, and the fibula is relatively robust without signs of the incipient fusion with the tibia observed in living cheetahs. In the radius, the tuber for the biceps muscle occupies about 10% of the shaft length in A. pardinensis as in most felines, while in the modern cheetah it is only half that long (muscle force tends to concentrate in the proximal part of the limb in the cheetah, as in all cursorial mammals).
More recently, the bones of the forelimb of a giant cheetah were found at the Georgian site of Dmanisi, and their study has revealed some interesting facts. The authors estimate that the body mass of that individual would be in the vicinity of 100 kilos, quite larger than the individual from France that I examined and more than twice the average weight of extant cheetahs. The humerus bone is far more stout than in modern cheetahs, probably in relation with the animal’s great mass, but otherwise the proportions of the bones are remarkably elongate.
Here is a photo of the Dmanisi giant cheetah forelimb exhibited at the National Museum of Georgia in Tbilisi (by the way, the small round objects are not cheetah bones, they are actually hyena coprolites!)
Other fossil sites, including Saint Vallier in France and Pantalla in Italy, have yielded amazing fossil skulls of A. pardinensis, showing a considerable but not total similarity with modern cheetahs. The skull was proportionally somewhat longer and lower than in A. jubatus, thus resembling more “conventional” cats. But the dentition is very similar to that of the modern cheetah, especially in the fact that the upper carnassial was remarkably blade-like, lacking the inner cusp or protocone. This feature indicates that the animal consumed little if any bone, and, just like modern cheetahs, it would hurriedly eat the more meaty parts if its prey and leave the rest for more powerful competitors.
All in all , we get a complex picture of A. pardinensis. Undoubtedly it would be an extremely fast sprint runner, but its adaptations were a little less refined than in its modern relative, which, combined with a greater body mass, almost surely implied that it would not be a faster animal, in spite of its longer legs. Once A. pardinensis made a kill, its blade-like carnassials allowed it to cut and consume skin and meat very efficiently, but it would probably not stay at the kill site long enough to consume any significant proportion of bone. And it makes sense that, in a world populated by large jaguars, sabertooths like Homotherium, giant hyenas like Pachycrocuta and packs of wolves, the elegant giant cheetah would not risk injury in a fight over a carcass. Just as in the modern cheetah, there was a price to pay for extreme sprinting efficiency. And just like its modern relative, its hunting would have been a true spectacle of nature. Ah, to see such a scene!
A couple of the earliest posts in this blog were devoted to the scanty record of cat fossil footprints, and in one of them I regretted the absence of any recognizable tracks of Smilodon. That was indeed an important hole in our knowledge because some specialists have long hypothesized that Smilodon would be a plantigrade cat. In fact, several kinds of sabertooh cats had features in their limb anatomy that were interpreted at some point as indicative of a plantigrade posture. Such features were present, for instance, in the skeleton of Homotherium, and back in the 1960s the famous paleontologist Bjorn Kurtén hypothesized that this animal walked on plantigrade hindlimbs. But, what does that really mean in terms of the locomotion an appearance of the living animal? Well, if Homotherium were plantigrade then its rump would be much lower, since the hindlimbs lost a whole segment (the metapodials) in height, and the part of the leg that rested on the ground would be proportionally much longer. The animal’s stride would become much shorter, and its gait, ungainly. One of the clearest ways to show the implications of that hypohesis is to create a detailed skeletal reconstruction of the animal in such a posture and compare it with the digitigrade alternative. I did such an experiment some time ago, and I found the results quite striking.
At any rate, other specialists such as R. Ballesio and L. Ginsburg made quite detailed analysis of the functional anatomy of the feet in sabertooths and convincingly argued that Homotherium, and in fact all members of the family Felidae, extinct or extant, were perfectly digitigrade, with the possible exception of the earliest species comprised in he genus Proailurus. My own research in collaboration with paleontologists like Angel Galobart, Alan Turner and Manuel Salesa, added further evidence to confirm the digitigrade stance of Homotherium.
But while there seems to be a growing consensus about the posture of Homotherium, some specialists still think that heavier, shorter-limbed sabertooths such as Smilodon or Xenosmilus would have been plantigrade, and one of their arguments is the sheer mass of these robust animals. Such views imply some degree of confusion between the normal standing or walking posture of an animal and its running abilities. It is an observed fact that many digitigrade carnivores, such as dogs, are fast, lightly built runners, while heavy, robust animals like bears are plantigrade. But this does not imply a real correspondence between build and posture, and one must rememeber that among extant cats the hyper-robust jaguar, for instance, is perfectly digitigrade, just like the agile cheetah is. Whatever the case, we still see skeletal reconstructions that show those extinct cats with a bear-like, plantigrade stance.
The details of the limb osteology of these animals fit better with a digitigrade posture, but finding the creatures’ fossilized footprints would go very far in proving their actual gait and posture. And finally, earlier this year, Argentinan scientists M. Magnussen and D. Boh reported the discovery of two sets of carnivore footprints in a Pleistocene site near the coastal city of Miramar that belong, with all likelihood, to Smilodon populator, the largest and heaviest species of the genus. The tracks are the right age, the right size and the right morphology to correspond to Smilodon, whose fossils miraculously happen to be present in the same locality. And there has never been a cat-like carnivore in South America that even approached the size of Smilodon, so the attribution of the footprints looks pretty safe.
What about the cat’s gait and posture? The footprints leave no doubt that the animal was digitigrade, just like the much smaller modern jaguar is. The footprints also confirm that the animal’s claws were retracted during the walk, although there is one interesting detail in one of the prints, that corresponds to a forepaw: a small mark on the inner side of the footprint would correspond to the position of the dewclaw, which doesn´t normally touch the ground in modern cats. But, given the remarkably short metapodials of Smilodon combined with the enormous size of its dew claw, it would make sense that it would touch the ground at least occasionally, as it seems to have done in this case. Also, the footprints’ enormous width corresponds well with the immense size of the paws of this predator, whose trail has been finally found, more than a century after its fossils were recognized by paleontologists as those of perhaps the most powerful cat ever to walk the Earth.
In a few days we will be heading for Botswana for one more edition of our “Drawing the Big Cats Safari”. Our main goal is to observe the felines, but that is only part of what we get: we actually get a ticket to ancient Africa. The big predators are one key piece in the giant puzzle of living ecosystems, and a place that still can sustain its large carnivores is a place where the laws of nature remain healthily at work, and for that reason I experience every safari as a kind of time-travel.
On each trip, as I board the safari vehicle for the first game-drive, I feel as if I enter a different dimension. Pristine landscapes, untouched vegetation and the diversity of wildlife bring my senses to a state of natural alertness -not in vain human kind evolved in the African savannah! One unforgettable first-day game drive took place in Samburu, Kenya, in 1999. We had spent most of the day driving from Nairobi, and we had only time for a short evening drive through the reserve on our way to the camp for the night. As we drove through the scenic riverine woods along the margins of the Ewaso Nyro river, we found another vehicle that had stopped on the margin of the dirt track: they were watching a female leopard that had just killed an impala ram. Althought the high branches of the palm trees were still golden with the last rays of the sun, the deep bush where the big cat stood with its prey was already in deep shadow. Everyone on board of the vehicles was silent, aware of facing a high natural drama. It was almost as if we didn´t have the right to spy on this decisive moment of life and death, as if both predator and prey were emitting a sort of primeval energy that gave us the goosebumps. We just couldn´t take our eyes from the golden spotted cat and the athletic shape and powerful horns of the fallen antelope. We remained there in awe for many minutes as the cat started to feed and its tiny cubs emerged from the bush, as did an adult-sized young from the previous year, but then we had to hurry for camp.
In later trips I have seen leopards with their prey on several occasions, and each time the prey was an impala. It seems the fates of these two species are tightly linked, but the fact is the impala is an older inhabitant of the African woods and savannahs than the leopard. In Kenya there were impalas (genus Aepyceros) rather similar to the modern ones as early as the late Miocene, some 6 million years ago, while the earliest fossils of leopard ancestors (genus Panthera) are known from fossil deposits of Pliocene age, some 5 million years ago, from the Himalayas. Some time afternwards, leopard-like cats entered Africa, where they are first recorded some 3.8 million years ago, but the ancestral impalas had not been free of predation in the meantime, because several species of sabertooth cats shared their African habitats since the Miocene.
The impala is so well adapted to the ecotone between grassland and woodland, that it has barely changed in 6 million years. Its acrobatic leaps are among the most sublime, if sometimes underrated, spectacles of Africa. We saw this impressive ram in Chobe, Botswana, in 2014
Becuase of my professional bias, during my African trips I can’t help imagining how would those same places look in the distant past, and what animals would occupy the ecological niches of the modern species. If we could travel back to the early Pleistocene, about 1,6 million years ago, we might come across a predation scene where an impala nearly identical to the modern ones would fall prey to a sabertooth cat of the genus Megantereon. About the same size as a leopard, Megantereon would behave similarly to the spotted pantherine in many ways: it would hunt its prey through careful stalking, approaching to within just a few meters before launching an explosive attack. If the kill took place in the grass, the cat would drag its prey as soon as possible to an area with good cover to hide it among the bushes. After all, big hyenas and lion-sized sabertooths (Homotherium) roamed the plains and were always eager to steal the smaller cat’s kills.
But the shape of Megantereon‘s teeth implied some behavioral differences: on one hand, the sabertooth cat would be less able to haul complete large carcasses up the trees, because of its relatively fragile canines. Lighter, partly consumed kills would be easier to handle, although the cat itself was a good climber and at least could always save its own life by climbing to the higher branches.
But the most important difference concerned the killing bite, which implied a lot more bloodshed than in the case of modern cats, and thus if we could see Megantereon within the few minutes after a kill, it would be a rather gory sight.
Here is a reconstruction of Megantereon whitei from the early Pleistocene of Africa, taking a breath as it drags its impala prey to the bush for quiet consumption. Part of my book project “Big Cats of Africa, Past and Present”
Today we still have impalas in Africa, but Megantereon is long gone, a proof of the vulnerability of extreme specialists like the sabertooths and the resilience of adaptable species like the impala -and the leopard. But that doesn’t mean I don´t miss the possibility of seeing such a magnificent beast as Megantereon was!
More than 3 million years ago, somewhere in Northeastern Spain, a volcano exploded and created a large crater. With time the crater was occupied by a lake, known by geologists as a maar. Today, the lake is dry and the crater walls have been largely levelled by erosion, but an exceptional fossil site bears witness to the events that took place there. The site, called Camp dels Ninots, is close to the village of Caldas de Malavella in Girona.
Maar lakes often create remarkably beautiful scenery, with their encircling walls covered by forests, but some of them hide something more sinister. One example is lake Nyos in Cameroon, which in 1986 emitted a large cloud of carbon dioxide that killed thousands of people and animals. Such toxic gas emmissions occur because the pocket of magma beneath the lake leaks the carbon dioxide into the water, and perturbations such as those caused by a landslide can cause the gas to emerge with disastrous effects.
Three million years ago around the Camp dels Ninots maar lake, a rich fauna thrived in a subtropical environment, much warmer than today. Rhinos, tapirs and heavy antelopes crossed the forests and came down the crater walls for a drink at the lake margin. But several of those animals died mysteriously at the shore, and their bodies floated into the lake where they ultimately sank. Their skeletons, completely articulated, got exquisitely preserved as fossils, without any trace of having been disturbed by scavengers. A likely explanation is that the lake belched a cloud of toxic gas, instantly killing all the animals along the shore.
As often happens, the animals’ doom was the paleontologists’ blessing, since the death of so many creatures led to their pristine preservation. As the local authorities planned for an on-site exhibit, I was asked to create several reconstructions of the Pliocene environments and fauna of Camp dels Ninots, including a scene showing the hypothetical origin of the fossil accumulation.
And here is the finished painting that can be seen today at the fossil site
The scene shows antelopes of the genus Alephis and a rhinoceros of the genus Stephanorhinus on the shore, already showing signs of intoxication, while a tapir (Tapirus) lies on the ground, already dead. The bodies of other antelopes float in the lake while a pair of cormorants that happened to fly too low are already falling.
This and other reconstructions of the fauna and environments of Camp dels Ninots can be seen as part of the outdoors exhibit. Thanks to the findings made at the site, we now know a lot more about the anatomy of several species of Pliocene mammals, but, alas, no sabertooth skeleton has been found there as yet. But I don´t give up hope.
In central France, another Pliocene maar lake fossil site, a little younger in age than Camp dels Ninots, has been known for about a century, and it has yielded the most complete skeletons known to science of the typical sabertooth cats of the Pliocene: Homotherium and Megantereon. For several decades the French site, known as Senéze, was exploited without any serious excavation methodology, so we don´t know much about the taphonomy of those early finds. But since the 1990s, new field campaigns have yielded more accurate data, suggesting that the fossil mammal skeletons from Senéze accumulated as landslides coming down the crater walls trapped the animals and dragged their bodies to the lake.
I took this photo of the mounted skeleton of Megantereon from Senéze, exhibited at the Natural History Museum of Basel (Switzerland), back in 1990. All other findings of Megantereon fossils are more fragmentary, so it is only thanks to the exceptional conditions of the volcanic maar lake that we know nearly every bone of this sabertooth cat.
Only a portion of the ancient lake shore at Camp dels Ninots has been excavated this far. Sabertooths like Dinofelis diastemata, whose skeleton is mostly unknown, probably inhabited the area at the time, so it is not impossible that the next excavation will yield an amazingly preserved specimen…who knows?
Volcanic eruptions have provided the right conditions for the preservation of some of the best sabertooth fossils known to science, and not only beacuse of maar lake sites. If you want to know more about volcanoes and sabertooths, read my book “Sabertooth”! http://www.amazon.com/Sabertooth-Life-Past-Mauricio-Ant%C3%B3n/dp/025301042X/ref=sr_1_1?s=books&ie=UTF8&qid=1459250381&sr=1-1&keywords=sabertooth
Visit the on-site exhibition at Camp dels Ninots:
Hyenas have long been the victims of human prejudice and superstition, from ancient tribal tales to “The Lion King”. That is a pity because it gets in the way of our perception of a group of amazing animals with incredible adaptations for their ecological niches.
Lions sometimes have a hard time defending their rightful kills against large hyena clans, but quite often it is the hyenas who lose their own prey to opportunistic lions. Such dynamics are not new, and there is every likelihood that the woodlands and prairies of the Miocene, Pliocene and Pleistocene witnessed comparable conflicts quite often.
In the Old World Plio-Pleistocene, it was the lion-sized sabertooths of the genus Homotherium who had to deal with the challenges of living next to a most impressive hyena: Pachycrocuta brevirrostris. This animal was considerably larger in its linear dimensions than the living spotted hyena, but it was also more robust, so its body mass would have been much larger.
P. breviorrostris shared all the adaptations of modern hyenas for cracking bones (massive, blunt premolar teeth, robust skull with a domed forehead) and for carrying large pieces of carcasses over long distances (long, well muscled neck, large scapula with a flat articulation for weight transmission, shortened back and hind limbs for stability). But its massive size took those adaptations to a different scale, and certainly it made the giant hyena a rival to reckon with for any competing predator.
This illustration shows Pachycrocuta cracking a large ungulate bone, and a schematic view of the anatomical features involved in this action. The massive muscles of mastication (temporalis and masseter) provided the huge force necessary to crack the bone with the premolar teeth, and the domed forehead helped to dissipate the stresses generated during the bite
But, was P. brevirrostris a scavenger and a kleptoparasite of predators such as the sabertooths, or did it kill much of its own prey? This is a good question and one to which we may never get a final answer. On one hand, its skull and dentition were adapted to process bone at a phenomenal scale, so it was clearly very well adapted to scavenging. In fact, the cutting blade of its carnassial teeth was slightly shorter than in the highly predaceous modern spotted hyena, leaving more room for the crushing section of the dentition, a detail that suggests a more scavenging lifestyle.
On the other hand, the huge body mass of P. brevirrostris made it less efficient for this animal to forage through the enormous distances required in order to come across such a dispersed resource as carrion is. More purely scavenging species, such as the modern brown and striped hyenas, are much lighter, and actually weight considerably less than the more predatory spotted hyena. And while a large body mass can be a problem for long-distance foraging, it can be an advantage for active hunting, since one or several heavy hyenas can be more effective at subduing and bringing down a large prey animal.
Whether it killed or scavenged most of its food, the fact is that Pachycrocuta had the habit of bringing lots of it back to its den sites, a habit which apparently explains the origin of several remarkable fossil sites. If nothing else, paleontologists need to be grateful to this gigantic bone cracker for its efforts to collect hundreds of bones and gather them in the places where they eventually became preserved as fossils.
A family group of P. brevirrostris gather at the den site, where the cubs play with some old bones. Such dens, when placed near seasonal lakes or waterholes, could be buried by mud during floods and the bones would be preserved as fossils