Once feared on the plains of North America, Archaeotherium, nicknamed “hell pigs”, today intrigue paleontologists with their unexpected diet. These massive creatures, close to hippos and cetaceans rather than modern-day pigs, have long been considered simple scavengers or clumsy herbivores. But a study led by Brynn Wooten and Larisa DeSantis of Vanderbilt University (Tennessee) rekindles the debate.
Presented at the 2025 meeting of the Society of Vertebrate Paleontology, this research is based on dental wear analyzes carried out on fossils from several American states. The results reveal a marked difference between large and small individuals. Some would have been capable of crushing bones, like hyenas. A discovery that requires us to rethink their ecological role within prehistoric ecosystems.
An unexpected portrait ofArchaeotherium
L'Archaeotheriumlong perceived as a simple prehistoric pig, turns out to be a much more complex animal than its nickname “” hell pig “. These mammals lived between the end of the Eocene and the beginning of the Miocene. That is around 30 million years ago, on the North American continent. Contrary to their porcine appearance, they belong to the entelodont family. They are an extinct group of suiforms more closely related to modern-day hippos and cetaceans than to domestic pigs. Their imposing morphology, with a skull occupying up to 30% of the body length, betrayed a particular adaptation to their environment.
According to data from fossils, certain species could exceed 2,000 kg, a mass equivalent to that of a bison. Their sturdy limbs, combined with a massive head with powerful jaws, suggest a capacity for active interaction with their environment. Whether in hunting, defense or consumption of hard resources. However, their brain remained particularly small in relation to the size of the body. Their brain/body ratio is comparable to that of reptiles. Brynn Wooten, a doctoral student at Vanderbilt University, points out that this characteristic indicates limited intelligence. She specifies LiveScience“ an intelligence much lower than that of modern carnivorous mammals “.
Scientific interest inArchaeotherium is based precisely on this contrast between advanced physical abilities and reduced cognitive skills. This unique combination raises questions about their ecological and social behaviors. And above all how did these animals interact with other species in their habitat.
Tooth wear as a window into diet
To understand the eating behaviors of
Archaeotheriumthe researchers relied on a method called tooth wear texture analysis (dental microwear texture analysis). It is used to study the microscopic surfaces of fossilized teeth. This technique is based on the three-dimensional examination of the enamel. Traces left by different types of food can be identified, without requiring digestive remains or direct behavioral observations.
The team analyzed teeth from various fossil sites across the United States — including Nebraska, Oregon, Colorado and South Dakota. The results reveal a significant divergence between large and small individuals of the genus
Archaeotherium. The larger ones show abrasion marks similar to those of lions and hyenas, species known to consume bones. These marks indicate that these animals exerted strong chewing pressure, enough to fracture the bones of other vertebrates.
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Conversely, the smallest individuals show tooth surfaces more marked by shearing. This type of wear characterizes animals feeding on vegetation or soft flesh. These results suggest that body size strongly influenced diet. The big ones Archaeotherium
would have had access to food resources that were more difficult to exploit — bones, woody tubers, bulky prey. While the smallest would have specialized in softer foods.
Ecological competition and differentiated food niche
The identification of distinct diets according to the size of the Archaeotherium sheds new light on their place in ancient food webs. We imagined uniform behavior within a species. However, this differentiation suggests that large and small individuals occupied complementary ecological niches. This thus reduced intraspecific competition. In other words, they coexisted by exploiting different resources.
This hypothesis is consistent with patterns observed in some modern species. For example, in crocodiles or bears, differences in size between individuals lead to varied diets. According to Larisa DeSantis, this strategy would have allowed several species or subpopulations to
Archaeotherium to survive in unstable environments. Like those of the Eocene-Miocene transition, characterized by climatic changes and plant disturbances.
The use of their powerful jaws by the big ones
Archaeotherium would also have had a social function. Namely: access the carcasses first, repel competitors, or impose a hierarchy of access to food. Their ability to crush bones could have constituted an advantage in consuming what other predators neglected. Concretely, by extracting bone marrow rich in calories, as modern hyenas do.
Conversely, small individuals would have optimized their survival by turning to a more plant-based or opportunistic diet. And above all less risky, with easier prey to capture or less competitive vegetation. This distribution of feeding behaviors, determined in part by morphology, sheds light on a form of ecological plasticity that is valuable for understanding the evolutionary dynamics of these species.
New perspectives on Paleogene ecosystems
The results of this study on dental wear of
Archaeotherium are not limited to a rereading of the behavior of these giant mammals. They enrich the understanding of Paleogene ecosystemspost-dinosaur period marked by rapid diversification of land mammals. At this time, North America saw the emergence of a varied fauna of carnivores, herbivores, and omnivores, in a changing and often competitive environment.
The coexistence of individuals of different sizes, with specialized diets, makes it possible to reconstruct a more finely structured food network than previously assumed. Far from a simplistic model where a taxon occupies a single role, the
Archaeotherium demonstrate that dietary strategies could vary even within a taxonomic group, according to physiological and ecological criteria.
Researchers are now considering using other techniques, such as analyzing calcium isotopes in teeth, to confirm actual bone consumption. This type of analysis could determine whether the isotopic signatures correspond to regular ingestion of bone material, reinforcing the idea of opportunistic scavenging or predatory behavior in large individuals.
This work is part of a broader approach aimed at reconstructing the relationships between species, the modes of competition and the resulting morphological adaptations. They show that even species extinct for millions of years can provide, through the careful study of their fossils, valuable lessons on the evolution of terrestrial life. THE
Archaeotherium thus become key witnesses of ecological adjustments during periods of climatic and environmental transition.
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