Tag Archives: giant short faced bear

What to call the giant cat from the Ice Age?

The Ice Age of the recent past was a fascinating time, full of superlative animals, especially the mammalian megafauna of North America. The Ice Age, also referred to as the Pleistocene epoch, lasted from 1.9 million years ago to 10,000 years ago, and was characterized by a series of glacial advances and retreats across much of the Northern Hemisphere. It was also a time of animal migrations between continents and of many species being exceptionally large.

Giant ground sloths, the giant short faced bear, saber-toothed cats, mammoths, and mastodons all tromped through what was to later become our backyards. Many people are surprised to learn that North America was also home to a very large cat, larger than the modern lion, given the scientific name Panthera atrox.

This big cat lived mostly across the western half of North America, and ranged into South America as far as Peru. Its remains are plentiful in the tar pits of Rancho La Brea. It is clear that this is a big animal. Estimates of body size suggest a weight of about 1,000 pounds, and that it stood 4 feet at the shoulder. For comparison, the modern African lion weighs in at about 375 pounds. This American cat would have been the second largest mammalian predator, right behind the giant short faced bear. (See How big was the Giant Short-faced bear?)

Panthera atrox

The giant American cat, Panthera atrox

However, understanding how this animal relates to other large cats has been difficult. Scientists have noticed similarities between P. atrox and the modern lion, tiger, and jaguar. For many years, P. atrox was thought to be a subspecies of the lion, and so it has popularly been called the American Lion, and even the American Cave Lion. If it is closely related to the African lion, it suggests that lions migrated out of Asia and into the New World during the Ice Age, expanding as far south as South America, and becoming extinct at the end of the age. Several other species are known to have done this, so that is not so unusual. But is it an accurate story?

In a recent paper on the subject (Christiansen and Harris 2009), researchers have come up with a different idea. They examined the skull and jaws of the big American cat and compared it with lions, tigers, and jaguars. They used a wide range of measurements to create a mathematical model of each species, and compared them to each other. The result? Panthera atrox does not seem to be a lion at all, but rather is closest to the modern jaguar.

Jaguars came into the New World from Asia during the early Pleistocene. It seems then that P. atrox and the modern jaguar species, P. onca, are derived from the early jaguar that came into North America, and that lions never made that long trek across. If these researchers are correct, we should not call this magnificent cat the American Lion.

Jaguar at Edinburgh Zoo

A jaguar, Panthera onca. By Pascal Blachier from Savoie, France.

So, what should we call it? Jaguars are native to the New World, so the word “American” seems a bit redundant in the name. And the simple scale and grandeur of the cat requires some adjective. “Mega Jaguar” seems a bit plain to me. What do you suggest?

Christiansen, P. and Harris, J. M. 2009. Craniomandibular morphology and phylogenetic affinities of Panthera atrox: implications for the evolution and paleobiology of the lion lineage. Journal of Vertebrate Paleontology 29(3):934-945.

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How big was the Giant Short-faced Bear?

The character of living things on land changed forever after the Cretaceous-Tertiary extinctions, 65 million years ago. The dinosaurs on land and the marine reptiles in the oceans went extinct, leaving way for mammals and birds to evolve into those niches once held by the “terrible lizards” (dinosaurs) and other giant reptiles.

Throughout the Cenozoic, sometimes “mammal-centrically” referred to as the Age of Mammals, these warm-blooded, fur-covered creatures diversified into a wide range of beasts, including humans. While many of the land mammals got very large, they never matched the recording-holding dinosaurs for superlative size on land.

The largest animals ever known to have lived actually evolved after the dinosaurs and are in fact alive today. An ancient lineage of mammals returned to the oceans and evolved into the modern whales. (See the note about the largest animals feeding upon the smallest).

People are always excited about the Carnivores, or meat-eating mammals. There is something about the dangerous and frightening that excites our primitive nerve centers, so the carnivores are among the most popular at the zoo. (Technical note here—the word carnivore is used in two ways. Carnivore (with a capital “C”) can refer to the class of mammals, the Carnivora, most of whom, but not all, are carnivores (with a lower case “c”), meaning they eat meat. So, not all carnivores are Carnivores, and not all Carnivores are carnivores. Got it? Good.) (Also, see the series on Dangerous Animals for additional exciting facts.)

For example, I recall a visit to the Cincinnati Zoo, and while watching the famed white tigers my young daughter was thrilled when one watched her intently and kept pace with her on the ground while she ran giggling high above on the wooden walkway. She thought that it was a special treat to have one of these magnificent animals take a special interest in her. She felt less special when we mentioned to her that the tiger may not have had cuddling on its mind.

Elsewhere (see related posts below) we have discussed the Giant Short-faced bear (GSFB), Arctodus simus, the great bear from the Ice Age that lived across North America. The GSFB is the largest mammalian Carnivore known, but just how big was it?

Recreation of the Giant Short-faced bear showing its size next to a human

Recreation of the Giant Short-faced bear showing its size next to a human

Many people have examined this question, and one study lays it out clearly (Christiansen 1999). Christiansen examined both the GSFB and its European cousin, the Cave Bear (Ursus spelaeus), another bear famous for its dimensions. Several skeletal measurements have been shown to correlate to overall body mass in mammals. It makes sense that large species have bones of greater relative diameter than small species, and the relationship is more or less linear. By making these measurements a very good estimate of body mass can be made for extinct mammals.

Christiansen used many skeletal measurements of modern carnivores with known body mass to create his linear equations and then plugged in both species of bears to see what the formulas suggested. The results of this study are clear—the GSFB far outweighed any of the modern bears and the cave bear.

These data suggested that a typical (average) GSFB would have weighed in at about 1,700 pounds. Given that there are exceptional individuals, it is estimated that a really large specimen could easily have weighed more than 2,200 pounds. In contrast, the cave bear seems to have a mean body mass of about 1,000 pounds, with exceptional individuals approaching the average for the GSFB.

To further help put this in context, below is a list of select modern and extinct animals and their average body masses. I threw in a couple of dinosaurs for good measure:


Body Mass (pounds)

Blue Whale


Brachiosaurus (extinct)


T. rex (extinct)


Giant Short-Faced Bear (extinct)


Kodiak Bear


North American Lion (extinct)


Cave Bear (extinct)


Polar Bear


African Lion


Indian Tiger


American Black Bear








Velociraptor (extinct)




Gray Wolf




Red Fox


No matter how you look at it, “Giant” is a good name for Arctodus!

Christiansen, P. 1999. What size were Arctodus simus and Ursus spelaeus (Carnivora: Ursidae)? Ann. Zool. Fennici 36(93-102).

Related posts:

GSFB, a Northern California Original

Denning behavior in the GSFB

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Denning behavior in the Giant Short-faced Bear

One of the most exciting things in paleontology to me is when we can begin to tease apart how extinct animals, animals that humans often never set eyes upon, lived their everyday lives. I am often amazed at how my colleagues can drill deep into questions that at first seem unanswerable; using creative ways to get answers from all the evidence that has survived, the bones, teeth, and sometimes trace fossils.

There are many examples of using the clues provided in the fossil record to come to better understand beasts from the past. In an earlier story, we looked at a disease process in Tyrannosaurus, and glimpsed how the mighty tyrant king could be brought down by a lowly protozoan. Here, we will explore some evidence for denning in the Giant Short-faced Bear (GSFB).

In a paper from several years ago Schubert and Kaufmann (2003) discussed the discovery of a GSFB in an Ozark cave. While incomplete, it is still one of the most complete specimens of the bear ever found. In addition to bones in partial articulation, they also found a thin layer of clay and minerals underneath the skeleton that preserves the remains of hair. Unfortunately, the hair is too deteriorated to tell us what color it was or exactly what its texture might have been, but its discovery is tantalizing.

This Ozark specimen is small compared to others of its species. There is a lot of evidence that there was a significant difference in size between male and female GSFBs. For example, at Rancho La Brea in southern California, both smaller and larger individuals have been found in contemporaneous deposits. It is easy to tell if the individuals are adult, so seeing large and small forms suggests two options: either there are two species, or there is one species with large and small individuals. It later is most likely. This is not surprising as all modern bears are sexually dimorphic.

Schubert and Kaufmann noted that over 1/3 of the known specimens of the GSFB come from caves, and that those specimens are smaller in general than the specimens found in open environments. (See the story about the type specimen, also found in a cave in northern California). It is logical to reason that the smaller individuals using the caves are predominately female.

Modern female bears are much more prone than males to den during periods of unfavorable conditions. And male bears are more likely to remain active throughout the year. It seems as if the GSFB followed a similar pattern—the females were using caves as denning sites, and were denning when they perished. In Cope’s original paper (1879), he called this new animal the cave bear of California—seems he was right.

From the accumulation of small bits of information we continuously piece together the lives of prehistoric beasts, slowly bringing them into sharper focus. That is the thrill of paleontology.

Cope, E. D. 1879. The cave bear of California. American Naturalist 13:791.
Schubert, B. W., and J. E. Kaufmann. 2003. A partial short-faced bear skeleton from an Ozark cave with comments on the paleobiology of the species. Journal of Cave and Karst Studies 65(2):101-110.

There are many other interesting facts here at Boneblogger. Just look around and enjoy.

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