| Name | Arctodus | Diet | Omnivorous |
| Name Meaning | “Bear Tooth” | Height | 1.8–2.5 meters (6–8 feet) |
| Pronunciation | Ark-toe-dus | Length | 2.5–3.5 meters (8–11.5 feet) |
| Era | Cenozoic – Quaternary Period | Weight | 800 kg (1,760 lbs) – 1,000 kg (2,200 lbs) |
| Classification | Mammalia, Carnivora & Ursidae | Location | USA and Mexico (North America) |
Arctodus Pictures
The Arctodus
Commonly known as the short-faced bear, Arctodus was a prehistoric bear genus that lived during the Pleistocene Epoch from 2.5 million to 11,000 years ago.
It is often referred to as the largest land carnivore of the Pleistocene Epoch and one of the largest meat-eating mammals that have ever lived.
However, this remains controversial because some experts think it might have been an omnivore.
Two species have been identified in the genus so far based on differences in their size.
Arctodus pristinus (lesser short-faced bear) is smaller, while Arctodus simus (giant short-faced bear) is bigger and better known from fossil remains.
Arctodus was North America’s most common bear species during the Pleistocene Epoch.
It went extinct along with other megafauna of North America and was among the last to disappear.
Despite being known from several fossils, there still isn’t enough to piece together the entire story of the Arctodus, and a few aspects of this short-faced bear’s lifestyle remain controversial.
In this post, we’ll detail what we currently know about this massive bear, describing what it looked like and how it might have lived based on available scientific evidence.
Physical Characteristics
Arctodus was an incredibly large bear.
Although it wasn’t quite the biggest bear genus ever (the South American Arctotherium holds that record), it was clearly one of the biggest ursines from North America.
Arctodus had a long, powerful neck and a deep chest.
As its common name suggests, the short-faced bear had a broad skull with a disproportionately short snout compared to modern bear species.
This shortened face gave the species a more dog-like appearance compared to other bears.
In fact, A. simus is also commonly referred to as the bulldog bear due to its appearance.
In terms of their overall size, both species of Arctodus show significant variation.
They both had a robust and muscular build, but A. simus was bigger.
Like all bear species, the short-faced bear exhibited sexual dimorphism, which means male members of the genus were significantly bigger than the females.
The average mass of A. pristinus has been estimated to be about 133 kilograms (293 pounds).
The giant short-faced bear, on the other hand, may have weighed as much as 800 kilograms (1,700 pounds) on average.
They stood at a height of about 1.80 meters (5.9 feet) at the shoulders and up to four meters (13 feet) when standing upright.
The highest recorded mass for the species is 957 kilograms (2,110 pounds).
Based on these size estimates, A. simus was the largest carnivorous mammal known to have lived in North America.
However, it was still slightly smaller than the Arctotherium, which had a more robust build and weighed up to 3,000 pounds.
Habitat and Distribution
Arctodus lived during the Pleistocene Epoch and had a wide geographic range throughout North America.
Based on available fossil evidence, the short-faced bear was arguably the most common bear species in Pleistocene North America.
The two species occupied had distinct geographical distributions.
The giant short-faced bear was more common in the western part of North America, ranging from Alaska and the Yukon territory all the way down to Mexico.
The range of the lesser short-faced bear was restricted to the southern part of the continent, with fossils being discovered as far as Florida, Mexico, and Texas.
Both species were fully terrestrial, and their range covered diverse habitats, including grasslands, open woodlands, and forested areas.
The Pleistocene Epoch in North America was a time of significant climatic fluctuations.
The continent experienced a series of glacial and interglacial periods characterized by the expansion and contraction of massive ice sheets or glacials, which caused significant changes in sea levels and altered terrestrial habitats as well.
The glacial periods were characterized by a tundra-like landscape with sparse vegetation.
The ice sheets retreated during interglacial periods, giving rise to temperate forests and grasslands.
Behavior and Diet
Arctodus had strong limbs adapted for efficient locomotion on land.
Some experts think this bear genus had relatively long legs compared to other bears, which likely contributed to its exceptional speed and agility.
It moved at a moderate-speed pacing gait and had more specialized locomotion compared to modern bears.
A top speed of about 40 to 45 kilometers per hour (25–28 miles per hour) has been proposed for this bear, with an average pace speed of 13.7 kilometers per hour (8.5 miles per hour).
These estimates are often disputed by experts who think the length of the Arctodus’ legs may have been overestimated.
Another highly controversial aspect of the short-faced bear’s lifestyle is its diet.
Although it is commonly described as a carnivore, recent studies seem to dismiss the idea that this bear was an apex predator capable of hunting large prey.
The Arctodus was built for speed and may have been capable of comfortably matching most of the available prey species of North America in a chase.
However, the heavy weight of this bear would have made it difficult to keep up the chase for long on its relatively thin legs.
The bear’s skeleton also wasn’t built for sharp turns, which would have made it difficult to chase down agile prey.
Due to these limitations, a hypercarnivorous diet is unlikely for the short-faced bear.
Instead, experts have proposed that the Arctodus was either a scavenger or even an omnivore.
Their dentition suggests an adaptation to eating different types of prey, which is consistent for an animal that feeds on carcasses.
The immense size of this bear would have also made it easier to steal the kill of other more specialized predators.
Studies have also shown similarities in the dentition of the Arctodus and that of modern bear species like the cave bear.
This suggests that the short-faced bear may have eaten plants sometimes, depending on availability.
In terms of social behavior, Arctodus is believed to have been a solitary animal.
The differences in skeleton size across different locations suggest that males and females were dimorphic and did not live together for long.
However, individuals may have come together temporarily during certain times, such as mating seasons or when resources were particularly abundant.
Life Cycle
It’s safe to assume that the life cycle of the short-faced bear is similar to that of modern bears.
This means they reproduced sexually and gave birth to live young after mating.
Mating likely occurred during specific seasons or periods of the year when individuals came together temporarily.
Female Arctodus would have given birth to one to three cubs after a long gestation period.
No direct evidence for maternal denning has been found for the Arctodus, but it is likely they exhibited this behavior as it has been observed in other related bear species.
Their cubs would have been entirely dependent on their mother for survival.
The growth pattern and maturity of this bear species are often compared to that of the American bear.
Females most likely reached sexual maturity between four and six years of age, while males became mature around six to eight years.
Evolution and History
Arctodus belongs to the subfamily Tremarctinae, a group of bears known for their relatively short faces compared to other bear species.
The evolution of this bear lineage can be traced back to the Late Miocene Epoch, approximately 13 million years ago.
The period was a time of significant diversification and widespread distribution of various species of bears occupying different ecological niches.
The main bear species of Pleistocene America, namely Arctodus, Arctotherium, and Tremarctos, diverged from the same common ancestor (Plionarctos) around 4.8 million years ago.
The lesser short-faced bear evolved first during the Early Pleistocene Epoch.
The bigger A. simus evolved around 1.1 million years ago.
The evolution of this species is characterized by an increase in size and robustness.
Experts think the giant short-faced bear evolved into a bigger size as an adaptation to compete better and dominate other large predators that were present in the North American ecosystem.
In addition to being bigger, A. simus also had a shorter snout, more robust teeth, and longer limbs compared to the lesser short-faced bear.
The relative proportions of their molars and premolars were also different.
These adaptations likely conferred advantages in terms of increased bite force and efficiency during hunting or scavenging for the bigger bear species.
The short face may have allowed A. simus to open its jaws wider, delivering a more powerful bite, which would have been advantageous for capturing and subduing large prey.
Interactions With Other Species
Arctodus was a large carnivorous mammal.
The nature of its interaction with other species in its ecosystem depends on whether or not it was a top predator in its habitat or an opportunist scavenger.
As a predator, the powerful build and speed of the Arctodus would have allowed it to pursue and capture large herbivorous mammals of the Pleistocene Epoch, such as the wild horses, bison, deer, mastodons, pronghorns, and giant ground sloths
The Arctodus also coexisted with other formidable predators of the Pleistocene like the saber-toothed cat (Smilodon) and the American lion (Panthera leo atrox).
These predators likely competed for similar prey, territory, and other resources.
As a scavenger, the large size of the Arctodus would have given it a significant advantage against smaller-sized Pleistocene predators.
These predators probably didn’t put up much of a fight against the short-faced bear due to the risk of injury or death from such a large and powerful animal.
This sort of behavior is similar to the interaction between grizzly bears and other carnivores today, like gray wolves.
Arctodus also faced competition from other ursine bears.
There was no significant overlap in the habitats of the two Arctodus species, so they probably didn’t have to compete with each other.
However, other large bear species, such as the black bears and brown were present in North America during the Pleistocene Epoch.
These bear species may have interacted actively, with the A. simus typically dominating their competitive interactions.
However, the brown bears persisted beyond the Pleistocene, while the short-faced bears died off due to their inability to adapt to changing environmental conditions.
Cultural Significance
The Arctodus lived during a time of significant diversity in the North American ecosystem. The Pleistocene Epoch is renowned for a large population of giant mammals commonly referred to as megafauna.
The short-faced bear is one of the most remarkable megafaunas in North America.
While the genus name Arctodus is not very popular, the common name “Short-faced bear” is well-known.
The bear is commonly referenced in books, documentaries, and scientific literature about prehistoric times and is often depicted as a powerful predator.
The imposing size and distinctive appearance of this bear make it an intriguing prehistoric animal both to scientists and the general public.
In the past, the Arctodus was commonly confused with other Pleistocene bear species like the Arctotherium and Tremarctos floridanus.
The discovery of new fossils and in-depth research has helped to clear up the confusion in their respective identities.
However, many lingering questions still persist about the different aspects of the Arctodus’ lifestyle, especially its feeding habits.
Recent studies suggest that Arctodus was likely an omnivore or an opportunist predator at best instead of the fierce apex predator of Pleistocene North America.
These new findings have not in any way diminished the reputation of the short-faced bear as one of the fiercest bear species to have ever lived.
Conclusion
Arctodus is a genus of short-faced bears that was alive in North America during the Pleistocene Epoch.
The massive bear includes two distinct species differentiated by the differences in their sizes.
A. pristinus (lesser-short-faced bear) lived in southern North America, while the giant short-faced bear lived in the Northwestern part of the continent.
This bear species was one of the most common North American megafaunas.
It lived in the forests and open grasslands of North America between 2.5 million till about 11,000 years ago.
Once thought to be a hypercarnivore, new studies now show that the Arctodus was most likely an omnivore adapted to a varied diet that includes plants and animals.
FAQs
What does the name “Arctodus” mean?
“Arctodus” is derived from Greek words. “Arcto” means “bear,” and “odus” means “tooth.”
The genus name of the short-faced bear translates as “bear-tooth,” likely referencing the species’ formidable teeth.
Did Arctodus coexist with humans?
Yes, Arctodus lived alongside early human populations in North America during the Pleistocene Epoch.
However, the exact nature of their interactions and whether humans played a role in their extinction are still topics of scientific investigation.
Why did Arctodus go extinct?
Although they went extinct at different times, the disappearance of the two species of Arctodus can be linked to ecological collapse caused by climate change.
The warming climate led to the replacement of the vegetation and prey that the bear species relied on, leading to their eventual decline.
Sources:
- https://iceage.museum.state.il.us/mammals/short-faced-bear-0
- https://en.wikipedia.org/wiki/Arctodus
- https://en.wikipedia.org/wiki/Tremarctinae
- https://therevelator.org/short-faced-bear-extinct/
- https://ielc.libguides.com/sdzg/factsheets/extinctshort-facedbear
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