What is a rectangular prisms missing vertex

Art by Bob Nicholls
Nowadays, when we envision the words “prey,” among modern mammalian fauna, few taxa come to mind as quickly as the hoofed mammals, better known as the ungulates. Indeed, for the better part of their entire evolutionary history, the ungulates have become entirely indistinguishable from the term “prey.” Across their two major modern branches, the artiodactyls (the “even-toed ungulates,” such as bovids, pigs, deer, hippos and giraffes) and the perissodactyls (the “odd-toed ungulates,” including horses, rhinos and tapir), the ungulates too have created an empire spanning nearly every continent, establishing themselves as the the dominant herbivores throughout their entire range. However, as a price for such success, their lot as herbivores have forced them into an unenviable position: being the food for the predators. Indeed, throughout the diets of most modern predators, ungulates make up the majority, if not the entirety, of their diet, becoming their counterparts in this evolutionary dance of theirs. They have become the lamb to their wolf, the zebra to their lion, the stag to their tiger. If there is a predator in need of lunch, chances are that there is an ungulate there to provide it. Of course, such a dynamic is not necessarily a recent innovation. For the last 15-20 million years, across much of the world, both new and old, the ungulates have served as prey for these predators through it all. Over the course of whole epochs, these two groups have played into these roles for millions of years, coevolving with each other in an eons-long game of cat-and-mouse. The shoes they fill are not new, but have existed for ages, and within their niches they have cultivated their roles to perfection. Indeed, with such a tenured history, it seems hardly surprising the ungulates are wholly inseparable from the terms “prey,” itself.
However, while this is the case now, as it has been for the last 15-20 million years, go back far enough, and we see that this dynamic is not as set in stone as we would think. Indeed, back during the Eocene and Oligocene, during the very earliest days of age of mammals, things were very different for the ungulates. While today they are considered little more than food for modern predators, during these olden days, the ungulates weren’t quite so benign. In fact, far from being fodder for top predators, the ungulates had turned the tables, instead becoming top predators themselves. Indeed, though nearly unheard of today, throughout much of the Eocene and Oligocene, carnivorous ungulates thrived in abundance, developing specializations for catching large prey and establishing themselves as top predators that competed alongside the more traditional carnivores, and even dominating them in some instances. Given such success, it’s no wonder that multiple such clades had arisen during this time. Such predators included the arctocyonids, a lineage of (ironically) hoof-less ungulates with large jaws and sharp teeth for capturing large prey. There were also the mesonychians, a lineage of dog-like ungulates with massive skulls and jaws that allowed them to reign as the top predator across much of the Eocene.
However, among these various lineages, one stands stands out among the rest, by far. Arising during the Eocene, this lineage, though superficially resembling modern pigs, hailed from one an ancient lineage of artiodactyls far removed from swine or most other ungulates in general, with few close relatives alive today. Through perhaps not the most predatory of the bunch, it was among the most formidable, as their superficially pig-like appearance came with giant predatory jaws and teeth unlike anything from the modern era. And of course, as if all of that wasn’t enough, this lineage also went on to earn arguably one of the most badass nicknames of any lineage of mammals, period. These predators, of course, were the entelodonts, a.k.a the “hell-pigs.” More so than any other predatory ungulate lineage, these formidable ungulates were the ones to turn the current paradigm upside down, becoming some of the largest and most dominant carnivores in their landscape, even with (and often in spite of) the presence of more traditional predators. Through impressive size, fearsome teeth and sheer tenacity, these animals became the top dogs of their time, ruling as behemoth-kings of their Paleogene kingdoms, domineering all comers, and throughout the ranks, one entelodont in particular demonstrated such dominance the best. Though not the largest or most powerful of their kind, it is one of the most iconic, being among the most well-known members of its lineage to date. Moreover, this enteledont also has some of the most complete life histories ever seen out of this clade, with its brutality and predatory prowess being displayed in the fossil record in a way seen in no other member of its kind. More than anything else, however, it was this predator that best turned the notion of “ungulates being prey” on its head, living in an environment that bore some of the largest carnivoran hypercarnivores to date and still reigning as the undisputed top predator of its domain. This fearsome beast was none other than Archaeotherium, icon of the entelodonts, terror of the Oligocene American west and undisputed king of the White River badlands.
The rise of Archaeotherium (and of entelodonts in general) is closely tied to the ascendancy of carnivorous ungulates as a whole, one of the earliest evolutionary success stories of the entire Cenozoic. Having become their own derived clade since the late Cretaceous, the ungulates were remarkably successful during the early Paleogene, as they were among the first mammalian clades to reach large sizes during those early days after the non-avian dinosaurs had gone extinct. As such, it was with incredible swiftness that, as the Paleogene progressed, the ungulates swooped upon the various niches left empty by the K-Pg mass extinction that killed the dinosaurs. This of course included the herbivorous niches we would know them for today, but this also included other, much more carnivore roles. Indeed, early on during the Paleogene, it was the ungulates that first seized the roles of large mammalian predators, becoming some the earliest large mammalian carnivores to ever live, well before even the carnivorans. Such predators included the arctocyonids, a lineage of vaguely dog-like, hoof-less ungulates with robust jaws and sharpened teeth that acted as some of earliest large carnivores of the Paleocene, with genera such as Arctocyon mumak getting up to the size of big cats. Even more prolific were the mesonychids. More so than what pretty much any other lineage of predator, it was the mesonychids that would stand out as the earliest dominant predators of the early Cenozoic. Growing up to the size of bears and with enormous, bone-crushing jaws, the mesonychids were among the most powerful and successful predators on the market at that time, with a near-global range and being capable of subjugating just about any other predator in their environments. Indeed, they, along with other carnivorous ungulates (as well as ungulates in general), were experiencing a golden age during this time, easily being the most prolific predators of the age. Given such prevalence, it should be no surprise that there would be yet another lineage of predatory ungulates would throw their hat into the ring, and by early Eocene, that contender would none other than the entelodonts.
The very first entelodonts had arisen from artiodactyl ancestors during the Eocene epoch, at a time when artiodactyls were far more diverse and bizarre than they are now. Through today known from their modern herbivorous representatives such as bovines, deer, and antelope, during the Paleocene and Eocene, the artiodacyls, as with most ungulates of that time, were stronger and far more predaceous, particularly when it came to one such clade of artiodactyls, the cetacodontamorphs. Only known today from hippos and another group of artiodactyls (one which will become relevant later), the cetacodantomorphs emerged out of Asia around 55 million years ago, at around the same time that artiodactyls themselves had made their debut. These animals included the first truly predatory artiodactyls, with many of them possessing large skulls with powerful jaws and sharp, predatory teeth. Among their ranks included animals as puny as Indohyus, a piscivorous artiodactyl the size of a cat, to as formidable as Andrewsarchus, a giant, bison-sized predator often touted as one of the largest predatory mammals to ever live. Given such a predatory disposition, it wouldn’t be long until this clade produced a lineage of truly diverse, truly successful predators, and by around 40 million years ago, that is exactly what they did, as it was at that time that the entelodonts themselves first emerged. From their Asian homeland, the entelodonts spread across the world, spreading through not only most of Eurasia but also colonizing North America as well, with genera such as Brachyhyops being found across both continents. Here, in this North American frontier, the entelodonts began to diversify further, turning into their most successful and formidable forms yet, and it was around the late Eocene and early Oligocene that Archaeotherium itself had entered the scene.
Just from a passing glance at Archaeotherium, it is clear how exactly it (as well as the other entelodonts) earned the nickname of “hell-pigs.” It was a bruiser for starters; its body bore a robust, pig-like physique, with prominent neural spines and their associated musculature forming a hump around the shoulder region, similar to the hump of a bison. With such a bulky physique came with it impressive size; the average A. mortoni had a head-body length of roughly 1.6-2.0 m (5.3-6.6 ft), a shoulder height of 1.2 m (4 ft) and a body mass of around 180 kg (396 lb) in weight (Boardman & Secord, 2013; Joeckel, 1990). At such sizes, an adult Archaeotherium the size of a large male black bear. However, they had the potential to get even bigger. While most Archaeotherium specimens were around the size described above, a select few specimens, labeled under the synonymous genus “Megachoerus,” are found to be much larger, with skulls getting up to 66% longer than average A. mortoni specimens (Foss, 2001; Joeckel, 1990). At such sizes and using isometric scaling, such massive Archaeotherium specimens would attained body lengths over 2.5 m (8.2 ft) and would have reached weighs well over 500 kg (1100 lb), or as big as a mature male polar bear. Indeed, at such sizes, it is already abundantly evident that Archaeotherium is a force to be recorded with.
However, there was more to these formidable animals than sheer size alone. Behind all that bulk was an astoundingly swift and graceful predator, especially in terms of locomotion. Indeed, the hoofed feet of Archaeotherium, along with other entelodonts, sported several adaptations that gave it incredible locomotive efficiency, essentially turning it into a speed demon of the badlands. Such adaptations include longer distal leg elements (e.g. the radius and tibia) than their proximal counterparts (e.g. the humerus and femur), fusion of the radius and ulna for increased running efficiency, the loss of the clavicle (collar-bone) to allow for greater leg length, the loss of the acromion to enhance leg movement along the fore-and-aft plane, the loss of digits to reduce the mass of the forelimb, the fusion of the ectocuneiform and the mesocuneiform wrist-bones, among many other such traits (Theodore, 1996) . Perhaps most significant of these adaptations is the evolution of the “double-pulley astragalus (ankle-bone),” a specialized modification of the ankle that, while restricting rotation and side-to-side movement at the ankle-joint, allows for greater rotation in the fore-and-aft direction, thus allowing for more more powerful propulsion from the limbs, faster extension and retraction of the limbs and overall greater locomotive efficiency (Foss, 2001). Of course, such a trait was not only found in entelodonts but in artiodactyls as a whole, likely being a response to predatory pressures from incumbent predatory clades arising at the same time as the artiodactyls (Foss, 2001). However, in the case of the entelodonts, such adaptations were not used for merely escaping predators. Rather, they were used to for another, much more lethal effect…
Such notions are further reinforced by the entelodonts most formidable aspect, none either than their fearsome jaws, and in this respect, Archaeotherium excelled. Both for its size and in general, the head of Archaeotherium was massive, measuring 40-50 cm (1.3-1.6 ft) in length among average A. mortoni specimens, to up to 78 cm (~2.6 ft) in the larger “Megachoerus” specimens (Joeckel, 1990). Such massive skulls were supported and supplemented by equally massive neck muscles and ligaments, which attached to massive neural spines on the anterior thoracic vertebrae akin to a bisons hump as well as to the sternum, allowing Archaeotherium to keep its head aloft despite the skulls massive size (Effinger, 1998). Of course, with such a massive skull, it should come as no surprise that such skulls housed exceptionally formidable jaws as well, and indeed, the bite of Archaeotherium was an especially deadly one. Its zygomatic arches (cheek-bones) and its temporal fossa were enlarged and expanded, indicative of massive temporalis muscles that afforded Archaeotherium astoundingly powerful bites (Joeckel, 1990). This is further augmented by Archaeotherium’s massive jugal flanges (bony projections of the cheek), which supported powerful masseter muscles which enhanced chewing and mastication, as well as an enlarged postorbital bar that reinforced the skull against torsional stresses (Foss, 2001). Last but not least, powerful jaws are supplemented by an enlarged gape, facilitated by a low coronoid process and enlarged posterior mandibular tubercles (bony projections originating from the lower jaw), which provided an insertion site for sternum-to-mandible jaw abduction muscles, allowing for a more forceful opening of the jaw (Foss, 2001). All together, such traits suggest a massive and incredibly fearsome bite, perhaps the most formidable of any animal in its environment.
Of course, none of such traits are especially indicative of a predatory lifestyle. Indeed, many modern non-predatory ungulates, like hippos, pigs and peccaries, also possess large, formidable skulls and jaws. However, in peeling back the layers, it is found there was more to the skull of Archaeotherium that lies in store. Indeed, when inspecting the animal closely, a unique mosaic of features is revealed; traits that make it out to be much more lethal than the average artiodactyl. On one hand, Archaeotherium possessed many traits similar to those of herbivores animals, as is expected of ungulates. For instance, its jaw musculature that allowed the lower jaw of Archaeotherium a full side-to-side chewing motion as in herbivores (whereas most carnivores can only move their lower jaw up and down)(Effinger, 1998). On the other hand, Archaeotherium wielded many other traits far more lethal in their morphology, less akin to a herbivore and far more akin to a bonafide predator. For instance, the aforementioned enlarged gape of Archaeotherium is a bizarre trait on a supposed herbivore, as such animals do not need large gapes to eat vegetation and thus have smaller, more restricted gapes. Conversely, many predatory lineages have comparatively large gapes, as larger gapes allow for the the jaws to grab on to more effectively larger objects, namely large prey animals (Joeckel, 1990).
Such a juxtaposition, however, is most evident when discussing the real killing instruments of Archaeotherium — the teeth. More so than any facet of this animal, the teeth of Archaeotherium are the real stars of the show, showing both how alike it was compared to its herbivores counterparts and more importantly, how it couldn’t be more different. For instance, the molars of Archaeotherium were quite similar to modern herbivores ungulates, in that they were robust, bunodont, and were designed for crushing and grinding, similar in form and function to modern ungulates like peccaries (Joeckel, 1990). However, while the molars give the impression that Archaeotherium was a herbivore, the other teeth tell a very different story. The incisors, for example, were enlarged, sharpened, and fully interlocked (as opposed to the flat-topped incisors seen in herbivores ungulates), creating an incisor array that was seemingly ill-suited for cropping vegetation and much more adept at for gripping, puncturing and cutting (Joeckel, 1990). Even more formidable were the canines. Like the modern pigs from which entelodonts derived their nicknames, the canines of Archaeotherium were sharp and enlarged to form prominent tusk-like teeth, but unlike pigs, they were rounded in cross-section (similar to modern carnivores like big cats, indicating more durable canines that can absorb and resist torsional forces, such as those from struggling prey) and were serrated to form a distinct cutting edge (Effinger, 1998; Joeckel, 1990; Ruff & Van Valkenburgh, 1987). These canines, along with the incisors, interlock to stabilize the jaws while biting and dismantling in a carnivore-like fashion. More strikingly, the canines also seem to act as “occlusal guides,” wherein the canines help align the movement and position of the rear teeth as they come together, allowing for a more efficient shearing action by the rear teeth. This function is seen most prevalently modern carnivorous mammals, and is evidenced by the canine tooth-wear, which is also analogous to modern predators like bears and canids (Joeckel, 1990). Indeed, going off such teeth alone, it is clear that Archaeotherium is far more predatory than expected of an ungulate. However, the real stars of the show, the teeth that truly betray the predatory nature of these ungulates, are the premolars. Perhaps the most carnivore-like teeth in the entelodont’s entire tooth row, the premolars of Archaeotherium, particularly the anterior premolars, are laterally compressed, somewhat conical in shape, and are weakly serrated to bear a cutting edge, giving them a somewhat carnivorous form and function of shearing and slicing (Effinger, 1998). Most strikingly of all, the premolars of Archaeotherium bear unique features similar not to modern herbivores, but to durophagous carnivores like hyenas, particularly apical wear patterns, highly thickened enamel, “zigzag-shaped” enamel prism layers (Hunter-Schraeger bands) on the premolars which is also seen in osteophagous animals like hyenas, and an interlocking premolar interface wherein linear objects (such as bones) inserted into jaws from the side would be pinned between the premolars and crushed (Foss, 2001). Taken together, these features do not suggest a diet of grass or vegetation like other ungulates. Rather, they suggest a far more violent diet, one including flesh as well as hard, durable foods, particularly bone. All in all, the evidence is clear. Archaeotherium and other entelodonts, unlike the rest of their artiodactyl kin, were not the passive herbivores as we envision ungulates today. Rather, they were willing, unrepentant meat-eaters that had a taste for flesh as well as foliage.
Of course, even with such lines of evidence, its hard to conclude that Archaeotherium was a true predator. After all, its wide gape and durophagous teeth could have just as easily been used for scavenging or even to eat tough plant matter such as seeds or nuts, as in peccaries and pigs, which themselves share many of the same adaptations as Archaeotherium, include the more carnivorous ones (e.g. the wide gape, using the canines as an occlusal guide, etc.). How exactly do we know that these things were veritable predators and not pretenders to the title. To this end, there is yet one last piece of evidence, one that puts on full display the predatory prowess of Archaeotherium —evidence of a kill itself. Found within oligocene-aged sediment in what is now Wyoming, a collection of various fossil remains was found, each belonging to the ancient sheep-sized camel Poebrotherium, with many of the skeletal remains being disarticulated and even missing whole hindlimbs or even entire rear halves of their body. Tellingly, many of the remains bear extensive bite marks and puncture wounds across their surface. Upon close examination, the spacing and size of the punctures leave only one culprit: Archaeotherium. Of course, such an event could still have been scavenging; the entelodonts were consuming the remains of already dead, decomposed camels, explaining the bite marks. What was far more telling, however, was where the bite marks were found. In addition bite marks being found on the torso and lumbar regions of the camels, various puncture wounds were found on the skull and neck, which were otherwise uneaten. Scavengers rarely feast on the head to begin with; there is very little worthwhile meat on it besides the brain, cheek-muscles and eyes, and even if they did feed on the skull and neck, they would still eat it wholesale, not merely bite it and then leave it otherwise untouched. Indeed, it was clear that this was no mere scavenging event. Rather than merely consuming these camels, Archaeotherium was actively preying upon and killing them, dispatching them via a crushing bite to the skull or neck before dismembering and even bisecting the hapless camels with their powerful jaws to preferentially feast on their hindquarters (likely by swallowing the hindquarters whole, as the pelvis of Poebrotherium was coincidentally the perfect width for Archaeotherium to devour whole), eventually discarding the leftovers in meat caches for later consumption (Sundell, 1999). With this finding, such a feat of brutality leaves no doubt in ones mind as to what the true nature of Archaeotherium was. This was no herbivore, nor was it a simple scavenger. This was an active, rapacious predator, the most powerful in its entire ecosystem.
Indeed, with such brutal evidence of predation frozen in time, combined with various dental, cranial, and post cranial adaptations of this formidable animal, it’s possible to paint a picture of how this formidable creature lived. Though an omnivore by trade, willing and able to feast on plant matter such as grass, roots and tubers, Archaeotherium was also a wanton predator that took just about any prey it wanted. Upon detecting its prey, it approached its vicim from ambush before launching itself at blazing speed. From there, its cursorial, hoofed legs, used by other ungulates for escape predation, were here employed to capture prey, carrying it at great speeds as it caught up to its quarry. Having closed the distance with its target, it was then that the entelodont brought its jaws to bear, grabbing hold of the victim with powerful jaws and gripping teeth to bring it to a screeching halt. If the victim is lucky, Archaeotherium will then kill it quickly with a crushing bite to the skull or neck, puncturing the brain or spinal cord and killing its target instantly. If not, the victim is eaten alive, torn apart while it’s still kicking, as modern boars will do today. In any case, incapacitated prey are subsequently dismantled, with the entelodont using its entire head and heavily-muscled necks to bite into and pull apart its victim in devastating “puncture-and pull’ bites (Foss, 2001). Prey would then finally be consumed starting at the hindquarters, with not even the bones of its prey being spared. Such brutality, though far from clean, drove home a singular truth: that during this time, ungulates were not just prey, that they were not the mere “predator-fodder” we know them as today. rather, they themselves were the predators themselves, dominating as superb hunters within their domain and even suppressing clades we know as predators today, least of all the carnivorans. Indeed, during this point in time, the age of the carnivorous ungulates had hit their stride, and more specifically, the age of entelodonts had begun.
Of course, more so than any other entelodont, Archaeotherium took to this new age with gusto. Archaeotherium lived from 35-28 million years ago during the late Eocene and early Oligocene in a locality known today as the White River Badlands, a fossil locality nestled along the Great Plains and Rocky Mountains. Though a chalky, barren landscape today, during the time of Archaeotherium, the White River Badlands was a swamp-like floodplain crisscrossed with rivers and interspersed with by a mosaic of forests concentrated around waterways, open woodlands and open plains. As with most ecosystems with such a lush disposition, this locale teemed with life, with ancient hornless rhinos, small horse-like hyracodonts and early camels roaming the open habitats while giant brontotheres, small early horses and strange, sheep-like ungulates called merycoidodonts (also known as “oreodonts”) dwelled within the dense forests. Within this locale, Archaeotherium stalked the open woodlands and riparian forests of its domain. Here, it acted as a dominant predator and scavenger across is territory, filling a niche similar to modern grizzly bears but far more predatory. Among its preferred food items would be plant matter such as roots, foliage and nuts, but also meat in the form of carrion or freshly caught prey. In this respect, smaller ungulates such as the fleet-footed camel Poebrotherium, a known prey item of Archaeotherium, would have made a for choice prey, as its small size would make it easy for Archaeotherium to dispatch with its powerful jaws, while the entelodonts swift legs gave it the speed necessary to keep pace with its agile prey.
However, the entelodont didn’t have such a feast all to itself. Just as the badlands teemed with herbivores, so too did it teem with rival predators. Among their ranks included fearsome predators such as Hyaenodon, a powerful, vaguely dog-like predator up to the size of wolves (as in H. horridus) or even lions (as in the Eocene-aged H. megaloides, which was replaced by H. horridus during the Oligocene). Armed with a massive head, fierce jaws and a set of knife-like teeth that could cut down even large prey in seconds, these were some of the most formidable predators on the landscape. There were also the nimravids, cat-like carnivorans that bore saber-teeth to kill large prey in seconds, and included the likes of the lynx-sized Dinictis, the leopard-sized Hoplophoneus and even the jaguar-sized Eusmilus. Furthermore, there were amphicyonids, better known as the bear-dogs. Though known from much larger forms later on in their existence, during the late Eocene and Oligocene, they were much smaller and acted as the “canid-analogues” of the ecosystem, filling a role similar to wolves or coyotes. Last but not least, there were the bathornithid birds, huge cariamiform birds related to modern seriemas but much larger, which filled a niche similar to modern seriemas or secretary birds, albeit on a much larger scale. Given such competition, it would seem that Archaeotherium would have its hands full. However, things are not as they appear. For starters, habitat differences would mitigate high amounts of competition, as both Hyaenodon and the various nimravids occupy more specialized ecological roles (being a plains-specialist and forest-specialist, respectively) than did Archaeotherium, providing a buffer to stave off competition: More importantly, however, none of the aforementioned predators were simply big enough to take Archaeotherium on. During the roughly 7 million years existence of Archaeotherium, the only carnivore that matched it in size was H. megaloides, and even that would have an only applied to average A. mortoni individuals, not to the much larger, bison-sized “Megachoerus” individuals. The next largest predator at that point would be the jaguars-sized Eusmilus (specifically E. adelos) which would have only been a bit more than half the size of even an average A. mortoni. Besides that, virtually every other predator on the landscape was simply outclassed by the much larger entelodont in terms of size and brute strength. As such, within its domain, Archaeotherium had total, unquestioned authority, dominating the other predators in the landscape and likely stealing their kills as well. In fact, just about the only threat Archaeotherium had was other Archaeotherium, as fossil bite marks suggest that this animal regularly and fraglantly engaged in intraspecific combat, usually through face-biting and possibly even jaw-wrestling (Effinger, 1998; Tanke & Currie, 1998). Nevertheless, it was clear that Archaeotherium was the undisputed king of the badlands; in a landscape of hyaenodonts and carnivorans galore, it was a hoofed ungulate that reigned supreme.
However, such a reign would not last. As the Eocene transitioned into the Eocene, the planet underwent an abrupt cooling and drying phase known as Eocene-Oligocene Transition or more simply the Grande Coupure. This change in climate would eliminate the sprawling wetlands and river systems that Archaeotherium had been depending on, gradually replacing it with drier and more open habitats. To its credit, Archaeotherium did manage to hang on, persisting well after the Grand-Coupure had taken place, but in the end the damage had been done; Archaeotherium was a dead-man-walking. Eventually, by around 28 million years ago, Archaeotherium would go extinct, perishing due to this change in global climate (Gillham, 2019). Entelodonts as a whole would persist into the Miocene, producing some of their largest forms ever known in the form of the bison-sized Daeodon (which was itself even more carnivorous than Archaeotherium), however they too would meet the same fate as their earlier cousins. By around 15-20 million years ago, entelodonts as a whole would go extinct. However, while the entelodonts may have perished, this was not the end of carnivorous ungulates as a whole. Recall that the cetacodontamorphs, the lineage of artiodactyls that produced the entelodonts, left behind two living descendants. The first among them were the hippos, themselves fairly frequent herbivores. The second of such lineage, however, was a different story. Emerging out of South Asia, this lineage of piscivorous cetacodontamorphs, in a an attempt to further specialize for the fish-hunting lifestyle, began to delve further and further into the water, becoming more and more aquatic and the millennia passed by. At a certain point, these carnivorous artiodactlys had become something completely unrecognizable from their original hoofed forms. Their skin became hairless and their bodies became streamlined for life in water. Their hoofed limbs grew into giant flippers for steering in the water and their previously tiny tails became massive and sported giant tail flukes for aquatic propulsion. Their noses even moved to the tip of their head, becoming a blowhole that would be signature to this clade as a whole. Indeed, this clade was none other than the modern whales, themselves derived, carnivorous ungulates that had specialized for a life in the water, and in doing so, became the some of the most dominant aquatic predators across the globe for millions of years. Indeed, though long gone, the legacy of the entelodonts and of predatory ungulates as a whole, a legacy Archaeotherium itself had helped foster, lives on in these paragons of predatory prowess, showing that the ungulates are more than just the mere “prey” that they are often made out to be. Moreover, given the success that carnivorous ungulates had enjoyed in the past and given how modern omnivorous ungulates like boar dabble in predation themselves, perhaps, in the distant future, this planet may see the rise of carnivorous ungulates once again, following in the footsteps left behind by Archaeotherium and the other predatory ungulates all those millions of years ago.

Art by Bob Nicholls
Nowadays, when we envision the words “prey,” among modern mammalian fauna, few taxa come to mind as quickly as the hoofed mammals, better known as the ungulates. Indeed, for the better part of their entire evolutionary history, the ungulates have become entirely indistinguishable from the term “prey.” Across their two major modern branches, the artiodactyls (the “even-toed ungulates,” such as bovids, pigs, deer, hippos and giraffes) and the perissodactyls (the “odd-toed ungulates,” including horses, rhinos and tapir), the ungulates too have created an empire spanning nearly every continent, establishing themselves as the the dominant herbivores throughout their entire range. However, as a price for such success, their lot as herbivores have forced them into an unenviable position: being the food for the predators. Indeed, throughout the diets of most modern predators, ungulates make up the majority, if not the entirety, of their diet, becoming their counterparts in this evolutionary dance of theirs. They have become the lamb to their wolf, the zebra to their lion, the stag to their tiger. If there is a predator in need of lunch, chances are that there is an ungulate there to provide it. Of course, such a dynamic is not necessarily a recent innovation. For the last 15-20 million years, across much of the world, both new and old, the ungulates have served as prey for these predators through it all. Over the course of whole epochs, these two groups have played into these roles for millions of years, coevolving with each other in an eons-long game of cat-and-mouse. The shoes they fill are not new, but have existed for ages, and within their niches they have cultivated their roles to perfection. Indeed, with such a tenured history, it seems hardly surprising the ungulates are wholly inseparable from the terms “prey,” itself.
However, while this is the case now, as it has been for the last 15-20 million years, go back far enough, and we see that this dynamic is not as set in stone as we would think. Indeed, back during the Eocene and Oligocene, during the very earliest days of age of mammals, things were very different for the ungulates. While today they are considered little more than food for modern predators, during these olden days, the ungulates weren’t quite so benign. In fact, far from being fodder for top predators, the ungulates had turned the tables, instead becoming top predators themselves. Indeed, though nearly unheard of today, throughout much of the Eocene and Oligocene, carnivorous ungulates thrived in abundance, developing specializations for catching large prey and establishing themselves as top predators that competed alongside the more traditional carnivores, and even dominating them in some instances. Given such success, it’s no wonder that multiple such clades had arisen during this time. Such predators included the arctocyonids, a lineage of (ironically) hoof-less ungulates with large jaws and sharp teeth for capturing large prey. There were also the mesonychians, a lineage of dog-like ungulates with massive skulls and jaws that allowed them to reign as the top predator across much of the Eocene.
However, among these various lineages, one stands stands out among the rest, by far. Arising during the Eocene, this lineage, though superficially resembling modern pigs, hailed from one an ancient lineage of artiodactyls far removed from swine or most other ungulates in general, with few close relatives alive today. Through perhaps not the most predatory of the bunch, it was among the most formidable, as their superficially pig-like appearance came with giant predatory jaws and teeth unlike anything from the modern era. And of course, as if all of that wasn’t enough, this lineage also went on to earn arguably one of the most badass nicknames of any lineage of mammals, period. These predators, of course, were the entelodonts, a.k.a the “hell-pigs.” More so than any other predatory ungulate lineage, these formidable ungulates were the ones to turn the current paradigm upside down, becoming some of the largest and most dominant carnivores in their landscape, even with (and often in spite of) the presence of more traditional predators. Through impressive size, fearsome teeth and sheer tenacity, these animals became the top dogs of their time, ruling as behemoth-kings of their Paleogene kingdoms, domineering all comers, and throughout the ranks, one entelodont in particular demonstrated such dominance the best. Though not the largest or most powerful of their kind, it is one of the most iconic, being among the most well-known members of its lineage to date. Moreover, this enteledont also has some of the most complete life histories ever seen out of this clade, with its brutality and predatory prowess being displayed in the fossil record in a way seen in no other member of its kind. More than anything else, however, it was this predator that best turned the notion of “ungulates being prey” on its head, living in an environment that bore some of the largest carnivoran hypercarnivores to date and still reigning as the undisputed top predator of its domain. This fearsome beast was none other than Archaeotherium, icon of the entelodonts, terror of the Oligocene American west and undisputed king of the White River badlands.
The rise of Archaeotherium (and of entelodonts in general) is closely tied to the ascendancy of carnivorous ungulates as a whole, one of the earliest evolutionary success stories of the entire Cenozoic. Having become their own derived clade since the late Cretaceous, the ungulates were remarkably successful during the early Paleogene, as they were among the first mammalian clades to reach large sizes during those early days after the non-avian dinosaurs had gone extinct. As such, it was with incredible swiftness that, as the Paleogene progressed, the ungulates swooped upon the various niches left empty by the K-Pg mass extinction that killed the dinosaurs. This of course included the herbivorous niches we would know them for today, but this also included other, much more carnivore roles. Indeed, early on during the Paleogene, it was the ungulates that first seized the roles of large mammalian predators, becoming some the earliest large mammalian carnivores to ever live, well before even the carnivorans. Such predators included the arctocyonids, a lineage of vaguely dog-like, hoof-less ungulates with robust jaws and sharpened teeth that acted as some of earliest large carnivores of the Paleocene, with genera such as Arctocyon mumak getting up to the size of big cats. Even more prolific were the mesonychids. More so than what pretty much any other lineage of predator, it was the mesonychids that would stand out as the earliest dominant predators of the early Cenozoic. Growing up to the size of bears and with enormous, bone-crushing jaws, the mesonychids were among the most powerful and successful predators on the market at that time, with a near-global range and being capable of subjugating just about any other predator in their environments. Indeed, they, along with other carnivorous ungulates (as well as ungulates in general), were experiencing a golden age during this time, easily being the most prolific predators of the age. Given such prevalence, it should be no surprise that there would be yet another lineage of predatory ungulates would throw their hat into the ring, and by early Eocene, that contender would none other than the entelodonts.
The very first entelodonts had arisen from artiodactyl ancestors during the Eocene epoch, at a time when artiodactyls were far more diverse and bizarre than they are now. Through today known from their modern herbivorous representatives such as bovines, deer, and antelope, during the Paleocene and Eocene, the artiodacyls, as with most ungulates of that time, were stronger and far more predaceous, particularly when it came to one such clade of artiodactyls, the cetacodontamorphs. Only known today from hippos and another group of artiodactyls (one which will become relevant later), the cetacodantomorphs emerged out of Asia around 55 million years ago, at around the same time that artiodactyls themselves had made their debut. These animals included the first truly predatory artiodactyls, with many of them possessing large skulls with powerful jaws and sharp, predatory teeth. Among their ranks included animals as puny as Indohyus, a piscivorous artiodactyl the size of a cat, to as formidable as Andrewsarchus, a giant, bison-sized predator often touted as one of the largest predatory mammals to ever live. Given such a predatory disposition, it wouldn’t be long until this clade produced a lineage of truly diverse, truly successful predators, and by around 40 million years ago, that is exactly what they did, as it was at that time that the entelodonts themselves first emerged. From their Asian homeland, the entelodonts spread across the world, spreading through not only most of Eurasia but also colonizing North America as well, with genera such as Brachyhyops being found across both continents. Here, in this North American frontier, the entelodonts began to diversify further, turning into their most successful and formidable forms yet, and it was around the late Eocene and early Oligocene that Archaeotherium itself had entered the scene.
Just from a passing glance at Archaeotherium, it is clear how exactly it (as well as the other entelodonts) earned the nickname of “hell-pigs.” It was a bruiser for starters; its body bore a robust, pig-like physique, with prominent neural spines and their associated musculature forming a hump around the shoulder region, similar to the hump of a bison. With such a bulky physique came with it impressive size; the average A. mortoni had a head-body length of roughly 1.6-2.0 m (5.3-6.6 ft), a shoulder height of 1.2 m (4 ft) and a body mass of around 180 kg (396 lb) in weight (Boardman & Secord, 2013; Joeckel, 1990). At such sizes, an adult Archaeotherium the size of a large male black bear. However, they had the potential to get even bigger. While most Archaeotherium specimens were around the size described above, a select few specimens, labeled under the synonymous genus “Megachoerus,” are found to be much larger, with skulls getting up to 66% longer than average A. mortoni specimens (Foss, 2001; Joeckel, 1990). At such sizes and using isometric scaling, such massive Archaeotherium specimens would attained body lengths over 2.5 m (8.2 ft) and would have reached weighs well over 500 kg (1100 lb), or as big as a mature male polar bear. Indeed, at such sizes, it is already abundantly evident that Archaeotherium is a force to be recorded with.
However, there was more to these formidable animals than sheer size alone. Behind all that bulk was an astoundingly swift and graceful predator, especially in terms of locomotion. Indeed, the hoofed feet of Archaeotherium, along with other entelodonts, sported several adaptations that gave it incredible locomotive efficiency, essentially turning it into a speed demon of the badlands. Such adaptations include longer distal leg elements (e.g. the radius and tibia) than their proximal counterparts (e.g. the humerus and femur), fusion of the radius and ulna for increased running efficiency, the loss of the clavicle (collar-bone) to allow for greater leg length, the loss of the acromion to enhance leg movement along the fore-and-aft plane, the loss of digits to reduce the mass of the forelimb, the fusion of the ectocuneiform and the mesocuneiform wrist-bones, among many other such traits (Theodore, 1996) . Perhaps most significant of these adaptations is the evolution of the “double-pulley astragalus (ankle-bone),” a specialized modification of the ankle that, while restricting rotation and side-to-side movement at the ankle-joint, allows for greater rotation in the fore-and-aft direction, thus allowing for more more powerful propulsion from the limbs, faster extension and retraction of the limbs and overall greater locomotive efficiency (Foss, 2001). Of course, such a trait was not only found in entelodonts but in artiodactyls as a whole, likely being a response to predatory pressures from incumbent predatory clades arising at the same time as the artiodactyls (Foss, 2001). However, in the case of the entelodonts, such adaptations were not used for merely escaping predators. Rather, they were used to for another, much more lethal effect…
Such notions are further reinforced by the entelodonts most formidable aspect, none either than their fearsome jaws, and in this respect, Archaeotherium excelled. Both for its size and in general, the head of Archaeotherium was massive, measuring 40-50 cm (1.3-1.6 ft) in length among average A. mortoni specimens, to up to 78 cm (~2.6 ft) in the larger “Megachoerus” specimens (Joeckel, 1990). Such massive skulls were supported and supplemented by equally massive neck muscles and ligaments, which attached to massive neural spines on the anterior thoracic vertebrae akin to a bisons hump as well as to the sternum, allowing Archaeotherium to keep its head aloft despite the skulls massive size (Effinger, 1998). Of course, with such a massive skull, it should come as no surprise that such skulls housed exceptionally formidable jaws as well, and indeed, the bite of Archaeotherium was an especially deadly one. Its zygomatic arches (cheek-bones) and its temporal fossa were enlarged and expanded, indicative of massive temporalis muscles that afforded Archaeotherium astoundingly powerful bites (Joeckel, 1990). This is further augmented by Archaeotherium’s massive jugal flanges (bony projections of the cheek), which supported powerful masseter muscles which enhanced chewing and mastication, as well as an enlarged postorbital bar that reinforced the skull against torsional stresses (Foss, 2001). Last but not least, powerful jaws are supplemented by an enlarged gape, facilitated by a low coronoid process and enlarged posterior mandibular tubercles (bony projections originating from the lower jaw), which provided an insertion site for sternum-to-mandible jaw abduction muscles, allowing for a more forceful opening of the jaw (Foss, 2001). All together, such traits suggest a massive and incredibly fearsome bite, perhaps the most formidable of any animal in its environment.
Of course, none of such traits are especially indicative of a predatory lifestyle. Indeed, many modern non-predatory ungulates, like hippos, pigs and peccaries, also possess large, formidable skulls and jaws. However, in peeling back the layers, it is found there was more to the skull of Archaeotherium that lies in store. Indeed, when inspecting the animal closely, a unique mosaic of features is revealed; traits that make it out to be much more lethal than the average artiodactyl. On one hand, Archaeotherium possessed many traits similar to those of herbivores animals, as is expected of ungulates. For instance, its jaw musculature that allowed the lower jaw of Archaeotherium a full side-to-side chewing motion as in herbivores (whereas most carnivores can only move their lower jaw up and down)(Effinger, 1998). On the other hand, Archaeotherium wielded many other traits far more lethal in their morphology, less akin to a herbivore and far more akin to a bonafide predator. For instance, the aforementioned enlarged gape of Archaeotherium is a bizarre trait on a supposed herbivore, as such animals do not need large gapes to eat vegetation and thus have smaller, more restricted gapes. Conversely, many predatory lineages have comparatively large gapes, as larger gapes allow for the the jaws to grab on to more effectively larger objects, namely large prey animals (Joeckel, 1990).
Such a juxtaposition, however, is most evident when discussing the real killing instruments of Archaeotherium — the teeth. More so than any facet of this animal, the teeth of Archaeotherium are the real stars of the show, showing both how alike it was compared to its herbivores counterparts and more importantly, how it couldn’t be more different. For instance, the molars of Archaeotherium were quite similar to modern herbivores ungulates, in that they were robust, bunodont, and were designed for crushing and grinding, similar in form and function to modern ungulates like peccaries (Joeckel, 1990). However, while the molars give the impression that Archaeotherium was a herbivore, the other teeth tell a very different story. The incisors, for example, were enlarged, sharpened, and fully interlocked (as opposed to the flat-topped incisors seen in herbivores ungulates), creating an incisor array that was seemingly ill-suited for cropping vegetation and much more adept at for gripping, puncturing and cutting (Joeckel, 1990). Even more formidable were the canines. Like the modern pigs from which entelodonts derived their nicknames, the canines of Archaeotherium were sharp and enlarged to form prominent tusk-like teeth, but unlike pigs, they were rounded in cross-section (similar to modern carnivores like big cats, indicating more durable canines that can absorb and resist torsional forces, such as those from struggling prey) and were serrated to form a distinct cutting edge (Effinger, 1998; Joeckel, 1990; Ruff & Van Valkenburgh, 1987). These canines, along with the incisors, interlock to stabilize the jaws while biting and dismantling in a carnivore-like fashion. More strikingly, the canines also seem to act as “occlusal guides,” wherein the canines help align the movement and position of the rear teeth as they come together, allowing for a more efficient shearing action by the rear teeth. This function is seen most prevalently modern carnivores mammals, and is evidenced by the canine tooth-wear, which is also analogous to modern predators like bears and canids (Joeckel, 1990). Indeed, going off such teeth alone, it is clear that Archaeotherium is far more predatory than expected of an ungulate. However, the real stars of the show, the teeth that truly betray the predatory nature of these ungulates, are the premolars. Perhaps the most carnivore-like teeth in the entelodont’s entire tooth row, the premolars of Archaeotherium, particularly the anterior premolars, are laterally compressed, somewhat conical in shape, and are weakly serrated to bear a cutting edge, giving them a somewhat carnivorous form and function of shearing and slicing (Effinger, 1998). Most strikingly of all, the premolars of Archaeotherium bear unique features similar not to modern herbivores, but to durophagous carnivores like hyenas, particularly apical wear patterns, highly thickened enamel, “zigzag-shaped” enamel prism layers (Hunter-Schraeger bands) on the premolars which is also seen in osteophagous animals like hyenas, and an interlocking premolar interface wherein linear objects (such as bones) inserted into jaws from the side would be pinned between the premolars and crushed (Foss, 2001). Taken together, these features do not suggest a diet of grass or vegetation like other ungulates. Rather, they suggest a far more violent diet, one including flesh as well as hard, durable foods, particularly bone. All in all, the evidence is clear. Archaeotherium and other entelodonts, unlike the rest of their artiodactyl kin, were not the passive herbivores as we envision ungulates today. Rather, they were willing, unrepentant meat-eaters that had a taste for flesh as well as foliage.
Of course, even with such lines of evidence, its hard to conclude that Archaeotherium was a true predator. After all, its wide gape and durophagous teeth could have just as easily been used for scavenging or even to eat tough plant matter such as seeds or nuts, as in peccaries and pigs, which themselves share many of the same adaptations as Archaeotherium, include the more carnivorous ones (e.g. the wide gape, using the canines as an occlusal guide, etc.). How exactly do we know that these things were veritable predators and not pretenders to the title. To this end, there is yet one last piece of evidence, one that puts on full display the predatory prowess of Archaeotherium —evidence of a kill itself. Found within oligocene-aged sediment in what is now Wyoming, a collection of various fossil remains was found, each belonging to the ancient sheep-sized camel Poebrotherium, with many of the skeletal remains being disarticulated and even missing whole hindlimbs or even entire rear halves of their body. Tellingly, many of the remains bear extensive bite marks and puncture wounds across their surface. Upon close examination, the spacing and size of the punctures leave only one culprit: Archaeotherium. Of course, such an event could still have been scavenging; the entelodonts were consuming the remains of already dead, decomposed camels, explaining the bite marks. What was far more telling, however, was where the bite marks were found. In addition bite marks being found on the torso and lumbar regions of the camels, various puncture wounds were found on the skull and neck, which were otherwise uneaten. Scavengers rarely feast on the head to begin with; there is very little worthwhile meat on it besides the brain, cheek-muscles and eyes, and even if they did feed on the skull and neck, they would still eat it wholesale, not merely bite it and then leave it otherwise untouched. Indeed, it was clear that this was no mere scavenging event. Rather than merely consuming these camels, Archaeotherium was actively preying upon and killing them, dispatching them via a crushing bite to the skull or neck before dismembering and even bisecting the hapless camels with their powerful jaws to preferentially feast on their hindquarters (likely by swallowing the hindquarters whole, as the pelvis of Poebrotherium was coincidentally the perfect width for Archaeotherium to devour whole), eventually discarding the leftovers in meat caches for later consumption (Sundell, 1999). With this finding, such a feat of brutality leaves no doubt in ones mind as to what the true nature of Archaeotherium was. This was no herbivore, nor was it a simple scavenger. This was an active, rapacious predator, the most powerful in its entire ecosystem.
Indeed, with such brutal evidence of predation frozen in time, combined with various dental, cranial, and post cranial adaptations of this formidable animal, it’s possible to paint a picture of how this formidable creature lived. Though an omnivore by trade, willing and able to feast on plant matter such as grass, roots and tubers, Archaeotherium was also a wanton predator that took just about any prey it wanted. Upon detecting its prey, it approached its vicim from ambush before launching itself at blazing speed. From there, its cursorial, hoofed legs, used by other ungulates for escape predation, were here employed to capture prey, carrying it at great speeds as it caught up to its quarry. Having closed the distance with its target, it was then that the entelodont brought its jaws to bear, grabbing hold of the victim with powerful jaws and gripping teeth to bring it to a screeching halt. If the victim is lucky, Archaeotherium will then kill it quickly with a crushing bite to the skull or neck, puncturing the brain or spinal cord and killing its target instantly. If not, the victim is eaten alive, torn apart while it’s still kicking, as modern boars will do today. In any case, incapacitated prey are subsequently dismantled, with the entelodont using its entire head and heavily-muscled necks to bite into and pull apart its victim in devastating “puncture-and pull’ bites (Foss, 2001). Prey would then finally be consumed starting at the hindquarters, with not even the bones of its prey being spared. Such brutality, though far from clean, drove home a singular truth: that during this time, ungulates were not just prey, that they were not the mere “predator-fodder” we know them as today. rather, they themselves were the predators themselves, dominating as superb hunters within their domain and even suppressing clades we know as predators today, least of all the carnivorans. Indeed, during this point in time, the age of the carnivorous ungulates had hit their stride, and more specifically, the age of entelodonts had begun.
Of course, more so than any other ettelodont, Archaeotherium took to this new age with gusto. Archaeotherium lived from 35-28 million years ago during the late Eocene and early Oligocene in a locality known today as the White River Badlands, a fossil locality nestled along the Great Plains and Rocky Mountains. Though a chalky, barren landscape today, during the time of Archaeotherium, the White River Badlands was a swamp-like floodplain crisscrossed with rivers and interspersed with by a mosaic of forests concentrated around waterways, open woodlands and open plains. As with most ecosystems with such a lush disposition, this locale teemed with life, with ancient hornless rhinos, small horse-like hyracodonts and early camels roaming the open habitats while giant brontotheres, small early horses and strange, sheep-like ungulates called merycoidodonts (also known as “oreodonts”) dwelled within the dense forests. Within this locale, Archaeotherium stalked the open woodlands and riparian forests of its domain. Here, it acted as a dominant predator and scavenger across is territory, filling a niche similar to modern grizzly bears but far more predatory. Among its preferred food items would be plant matter such as roots, foliage and nuts, but also meat in the form of carrion or freshly caught prey. In this respect, smaller ungulates such as the fleet-footed camel Poebrotherium, a known prey item of Archaeotherium, would have made a for choice prey, as its small size would make it easy for Archaeotherium to dispatch with its powerful jaws, while the entelodonts swift legs gave it the speed necessary to keep pace with its agile prey.
However, the entelodont didn’t have such a feast all to itself. Just as the badlands teemed with herbivores, so too did it teem with rival predators. Among their ranks included fearsome predators such as Hyaenodon, a powerful, vaguely dog-like predator up to the size of wolves (as in H. horridus) or even lions (as in the Eocene-aged H. megaloides, which was replaced by H. horridus during the Oligocene). Armed with a massive head, fierce jaws and a set of knife-like teeth that could cut down even large prey in seconds, these were some of the most formidable predators on the landscape. There were also the nimravids, cat-like carnivorans that bore saber-teeth to kill large prey in seconds, and included the likes of the lynx-sized Dinictis, the leopard-sized Hoplophoneus and even the jaguar-sized Eusmilus. Furthermore, there were amphicyonids, better known as the bear-dogs. Though known from much larger forms later on in their existence, during the late Eocene and Oligocene, they were much smaller and acted as the “canid-analogues” of the ecosystem, filling a role similar to wolves or coyotes. Last but not least, there were the bathornithid birds, huge cariamiform birds related to modern seriemas but much larger, which filled a niche similar to modern seriemas or secretary birds, albeit on a much larger scale. Given such competition, it would seem that Archaeotherium would have its hands full. However, things are not as they appear. For starters, habitat differences would mitigate high amounts of competition, as both Hyaenodon and the various nimravids occupy more specialized ecological roles (being a plains-specialist and forest-specialist, respectively) than did Archaeotherium, providing a buffer to stave off competition: More importantly, however, none of the aforementioned predators were simply big enough to take Archaeotherium on. During the roughly 7 million years existence of Archaeotherium, the only carnivore that matched it in size was H. megaloides, and even that would have an only applied to average A. mortoni individuals, not to the much larger, bison-sized “Megachoerus” individuals. The next largest predator at that point would be the jaguars-sized Eusmilus (specifically E. adelos) which would have only been a bit more than half the size of even an average A. mortoni. Besides that, virtually every other predator on the landscape was simply outclassed by the much larger entelodont in terms of size and brute strength. As such, within its domain, Archaeotherium had total, unquestioned authority, dominating the other predators in the landscape and likely stealing their kills as well. In fact, just about the only threat Archaeotherium had was other Archaeotherium, as fossil bite marks suggest that this animal regularly and fraglantly engaged in intraspecific combat, usually through face-biting and possibly even jaw-wrestling (Effinger, 1998; Tanke & Currie, 1998). Nevertheless, it was clear that Archaeotherium was the undisputed king of the badlands; in a landscape of hyaenodonts and carnivorans galore, it was a hoofed ungulate that reigned supreme.
However, such a reign would not last. As the Eocene transitioned into the Eocene, the planet underwent an abrupt cooling and drying phase known as Eocene-Oligocene Transition or more simply the Grande Coupure. This change in climate would eliminate the sprawling wetlands and river systems that Archaeotherium had been depending on, gradually replacing it with drier and more open habitats. To its credit, Archaeotherium did manage to hang on, persisting well after the Grand-Coupure had taken place, but in the end the damage had been done; Archaeotherium was a dead-man-walking. Eventually, by around 28 million years ago, Archaeotherium would go extinct, perishing due to this change in global climate (Gillham, 2019). Entelodonts as a whole would persist into the Miocene, producing some of their largest forms ever known in the form of the bison-sized Daeodon (which was itself even more carnivorous than Archaeotherium), however they too would meet the same fate as their earlier cousins. By around 15-20 million years ago, entelodonts as a whole would go extinct. However, while the entelodonts may have perished, this was not the end of carnivorous ungulates as a whole. Recall that the cetacodontamorphs, the lineage of artiodactyls that produced the entelodonts, left behind two living descendants. The first among them were the hippos, themselves fairly frequent herbivores. The second of such lineage, however, was a different story. Emerging out of South Asia, this lineage of piscivorous cetacodontamorphs, in a an attempt to further specialize for the fish-hunting lifestyle, began to delve further and further into the water, becoming more and more aquatic and the millennia passed by. At a certain point, these carnivorous artiodactlys had become something completely unrecognizable from their original hoofed forms. Their skin became hairless and their bodies became streamlined for life in water. Their hoofed limbs grew into giant flippers for steering in the water and their previously tiny tails became massive and sported giant tail flukes for aquatic propulsion. Their noses even moved to the tip of their head, becoming a blowhole that would be signature to this clade as a whole. Indeed, this clade was none other than the modern whales, themselves derived, carnivorous ungulates that had specialized for a life in the water, and in doing so, became the some of the most dominant aquatic predators across the globe for millions of years. Indeed, though long gone, the legacy of the entelodonts and of predatory ungulates as a whole, a legacy Archaeotherium itself had helped foster, lives on in these paragons of predatory prowess, showing that the ungulates are more than just the mere “prey” that they are often made out to be. Moreover, given the success that carnivorous ungulates had enjoyed in the past and given how modern omnivorous ungulates like boar dabble in predation themselves, perhaps, in the distant future, this planet may see the rise of carnivorous ungulates once again, following in the footsteps left behind by Archaeotherium and the other predatory ungulates all those millions of years ago.

In the intricate web of evidence and testimony woven by the prosecution in Steven Avery's case, one crucial element often overlooked is the curious case of item BZ. This collection of bone fragments and muscle tissue, deemed "unquestionably human" by forensic anthropologist Leslie Eisenberg, surfaced within a tarp filled with ash and debris on November 10th, 2005. This discovery was made by Rodney Pevytoe and Tom Sturdivant at the Calumet County Sheriff’s Department storage area, where evidence from the case was held. The tarp, allegedly originating from the sifting of Avery's burn pit on November 8th, assumes pivotal significance in linking Avery to the remains of Teresa Halbach.
At the heart of the matter lies a tissue sample from one of the bone fragments in item BZ, yielding a partial DNA profile matching Teresa Halbach's pap smear. This single piece of evidence provided the State with a crucial link, connecting the recovered remains to Steven Avery. Had the State not asserted that item BZ originated from the burn pit, the task of convicting Avery would have been considerably more arduous. However, by staking their claim on item BZ's origin, the State inadvertently constrained themselves, leaving no room for retreat.
In the following analysis, we embark on a detailed examination of why the State's assertion regarding item BZ is not merely dubious but downright implausible. While direct photographic evidence of the burn pit's contents is lacking, we delve into the intricacies of the sifting process conducted on November 8th. By dissecting the equipment utilized, the logistics involved, and the personnel present, we endeavor to paint a vivid picture of the circumstances surrounding the burn pit examination.
Subsequently, we scrutinize the dimensions and physical characteristics of the bone and tissue fragments comprising item BZ. Through this lens, we assess the feasibility and likelihood of these items being overlooked during the meticulous sifting process. A critical point of comparison emerges as we juxtapose the contents of item BZ with those of property tag number 8318—the infamous box of bones recovered from the burn pit on November 8th. Discrepancies in the condition and composition of these bone fragments offer valuable insights into the integrity of the State's narrative.
Furthermore, we confront the absence of cadaver dog alerts at Steven's burn pit—a glaring inconsistency considering the trained ability of these canines to detect human remains. We ponder the improbability of a relatively unburnt piece of muscle tissue evading detection in an area ripe for cadaver dog interest.
By the conclusion of the analysis, supported by comprehensive information and visual aids, the implausibility of item BZ's connection to the burn pit becomes irrefutable. The evidence points unequivocally to an alternative origin for item BZ, rendering the State's assertion untenable. Through a synthesis of logical deduction and empirical examination, we invite readers to embrace a perspective grounded in common sense—a perspective that unequivocally rejects the notion that item BZ emerged from Steven Avery's burn pit on November 8th, 2005.
On November 8, 2005, a team including John Ertl, Charles Cates, Guang Zhang from the Wisconsin State Crime Laboratory, Jason Jost from Manitowoc County Sheriff's Department, and Tom Sturdivant from DCI meticulously sifted through Steven Avery's burn pit. Let’s first give you a description and a visual of the equipment they were using to sift the burn pit that day. Ertl describes the equipment as follows:
"It's three aluminum poles that hook together to form a tripod, stands about 6 feet tall. There are chains coming down from the center top of the tripod to which we attach an aluminum frame, so it kind of can swing within the tripod. And on that aluminum frame, we can put different size mesh. You put the materials on top of the mesh and you can use a trowel, or a broom, or just shaking, whatever works best for the material. And then the particles or bits that won't fall through the screen, we put a tarp under there and saved those for later analysis, if needed."
Here’s a visual of what the sifting equipment they were using would have looked like:
Similar sifting equipment that was used at the burn pit on 11/8
Let’s hear how Ertl describes the process that took place that day:
Q: All right. And who participated in the processing of this burn pit? A: The three of us assisted, and, uh, the person in charge with that area was Tom Sturdivant, Special Agent, with the Division of Criminal Investigations.
Q: All right. And, urn, tell us how you proceeded to process that pit? A: There were also additional officers present who assisted in the sifting process. I was the one who shoveled the materials from the ground up to the sifting platform, and then there were probably four, five, or six of us standing around the sifter at any time collecting things and placing them in boxes. We sifted through all the ash and material that was in that area.
Q: Now, if you would, describe for us exactly how the shovel was used to remove debris and other materials from this pit and brought to the sifter. Tell us about how that was conducted? A: Okay. We set the sifter up, and just past the end of that frame from that car seat. The shovel we used was one that we carried with us for this purpose. The sifter we usually use is for exhuming gravesites. So we'll shovel out the material and sift through it looking for bones or bullets or whatever from a gravesite. In this case we had very hard ground and then on top of that was maybe around six inches of ashen material. It's a flat blade shovel, sort of like a garden spade, and that was used sort of like a dustpan to scoop up the ash, and then I stood up, turned around, and took a step, and set it on the screen. And then the people around the screen would pick through it. The smaller material would fall through the screen onto a tarp, and the larger materials they would collect and put in a box.
Q: What efforts did you undertake to ensure that you wouldn't damage or create any harm to any of the debris that was being recovered from the pit? A: Well, it was done carefully. I guess that's what I can say. We didn't look real hard at the materials we were collecting. My advice to the people around the sifter was, if you're not sure, just put it in the box. Someone else will figure out later what it is. So we didn't spend time picking at the things that we were collecting. The shovel - We had a hard surface. It's just pick up the ash with it. I mean, it wasn't like we had to dig and put your foot on it and push down and dig or anything. It wasn't necessary. So it was a pretty gentle process.
Q: Tell us about the sifting part of the process? A: It’s sort of like hardware cloth, and we carry it – three different grades of it. I think there’s a half-inch mesh, a quarter-inch mesh, and an eighth-inch mesh, and we put this material through the quarter-inch mesh. So one scoopful at a time is placed onto the mesh, and the mesh is probably, three-foot by three-and-a-half-foot rectangular area, and then the five people would, with their gloved hands, I believe some of them had a mason's trowel, it's about this big, triangular metal-shaped object with a handle, to move the ash on the screen, spread it out, and then you can sort of tap the screen and it sort of jiggles the material, and the finer particles fall through.
Q: All right. Did you, or any of your team who participated in this process, recognize any of the debris as human remains? A: We recognized it as remains for sure. There were things that looked like teeth. Things that looked like bone. Nothing bigger than the palm of my hand. But whether it was human remains or not, we weren't sure.
Q: Most of the items were very small? A: Yes, they were.
Q: All right, Approximately how long did this process last? A: Well, they had asked for the sifter at about 3pm and we worked until it got dark. It was just after 5pm. So about two hours.
Q: And what did you do at the scene as you wrapped up this, um, processing for that evening? A: Well, once we had sifted all the materials, then we had what was collected in boxes. We packaged that up. That was eventually turned over to Calumet County. The material that was fallen through the screen onto the tarp was also saved, and Tom Sturdivant took care of that. And we just cleaned up the sifter and put it away, and then we proceeded to our next task.
Q: How was the, um, material preserved that had fallen through the screen? A: It was fallen through onto a tarp, and it’s my understanding that Tom Sturdivant was going to keep that. How he did that, I don’t know.
Q: All right. In other words, you left that scene before the complete wrap-up as it were, had undertaken? A: Yes.
Now let’s keep in mind that this wasn’t a massive operation that had to take place on the 8th. The burn pit was a relatively small rectangular area with a couple inches of loose ash sitting on top of hard-packed soil – meaning, there really wasn’t a large scale of ash and debris they had to go through – which is why Ertl said they sifted through ALL of the ash and material that was in that area. Take a look for yourself – the first picture is taken on 11/6, two days before any sifting is done. The second picture is taken a few days after the 8th showing the missing loose ash and debris from the burn pit. Again, there wasn’t a ton to go through.
https://preview.redd.it/l3jh5am7780d1.png?width=975&format=png&auto=webp&s=b1a32e80819b9d176cb4d1e6f48ee23eeb3ad003
https://preview.redd.it/qhqeq1pb780d1.png?width=975&format=png&auto=webp&s=ab26f290963dbe8d6dd189e99b8bfebca38ced5a
Ertl tells us at trial that they didn’t even dig down into the hard-packed soil on the 8th, Ertl simply used his shovel like a dust pan to collect the loose ash and debris in the burn pit, place each shovel full on the sifting screens, the other people were all standing around the sifting screen shaking it, spreading out the ash with their hands, and even using some tools to get the finer material. They used a quarter-inch mesh sifting platform designed to catch larger pieces while letting smaller debris fall through onto a tarp. Given this setup, we can say with certainty that there's no conceivable way that several of the bones and tissue fragments in item BZ could have gone unnoticed.
Ertl's team spent about two hours carefully sifting through the burn pit, with 4-6 people examining each batch. The largest bone fragment in item BZ was 59.2 mm (about 2.3 inches), and the largest piece of muscle tissue was 61.3 mm by 30 mm (about 2.4 inches by 1.2 inches). These are significant pieces that would've stood out during the sifting process. Ertl's team was instructed to collect anything potentially significant, and Ertl himself testified that if there was any doubt about whether something was important, they should put it in the evidence box. So how on earth could these large, distinctive fragments have slipped through the sifting process without being noticed??
Item BZ
The notion that these large fragments could have passed through a quarter-inch mesh is not only absurd—it’s physically impossible. Additionally, both Jason Jost and Tom Sturdivant, who were involved in the initial search, claimed they could see bones in the burn pit from 8 feet away. If they could spot bones from that distance, there's no way they would miss the larger, more noticeable fragments in item BZ as they were sorting through the ash/debris with their hands. It simply doesn't make sense.
Let's talk about burn characteristics. The bones in box 8318—the initial collection from the burn pit—show signs of intense heat exposure, or calcination. Calcined bones are typically dry, rigid, and often white or black from the burning process. Have a look yourself.
Property tag #8318
In stark contrast, the bone fragments in item BZ are far less burned, with some of the tissue retaining a squishy consistency. Here’s an unedited picture again of all of item BZ.
Item BZ
If item BZ came from the same burn pit as the items you see in 8318, you'd expect there to be SOMETHING in that box of bones that looks like one of the unburned items in BZ – right? The fact that we are to believe that somehow every single fragment that is in item BZ (that looks nothing like any of the bones in 8318) were all coincidentally ‘missed’ on 11/8 is ridiculous. Clearly, item BZ was never mixed in with Steven's burn pit and the loose ash that was sifted from there on 11/8.
Finally, Cadaver dogs are specifically trained to detect human remains, even in trace amounts. If item BZ's muscle tissue had been in the burn pit, these dogs would have certainly been drawn to this area very early on in the investigation. Yet, during the entire time HRD dogs were present on the Avery Salvage yard (11/5 - 11/10), there were no alerts from cadaver dogs at Steven's burn pit. Think about that for a moment. These dogs are highly skilled, and if human tissue was in the burn pit, they would have found it. The lack of alerts strongly suggests that item BZ wasn't in the burn pit.
The state's excuse that Bear, Steven's German shepherd chained near the burn pit, prevented officers or cadaver dogs from accessing the burn pit is extremely weak. Professional handlers are trained to manage dog behavior. If a cadaver dog had detected the smell of human remains in Steven's burn pit, removing Bear would have been a simple task and would have been done immediately.
Here's the bottom line: item BZ could not have come from Steven Avery's burn pit. As we question its origins and implications, we're left to ponder: where did BZ truly come from?