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Giant Short-Faced Bear Reexamined

As the old saying goes, looks can be deceiving. That is the theme of a new paper on the Giant Short-Faced Bear (GSFB), Arctodus simus, recently published in the Journal of Vertebrate Paleontology (Figueirido et al., 2010).

We have explored this beast in other posts (see below), and will no doubt do so in the future, as it is one of my favorite animals because of the fascinating paradoxes that it presents. Bears as a group often do not do what we think they should do!

The GSFB is the largest mammalian carnivore known, fossil or recent. First discovered in Northern California and described by Cope in 1879, remains of this species have since been recognized from Alaska to Mexico, and from the west coast east to Pennsylvania in North America. It lived from about 1 million years to about 10,000 years ago. It is likely that they became extinct as an ultimate effect of climate change at the end of the Ice Age.

Kurten (1967) was one of the first to look at the GSFB in much detail, and he made a number of observations  that have come to define this bear: shortened face like a cat, and extremely long limbs compared to body length. Kurten argued that those adaptations show a hypercarnivore, a cat-like giant predatory bear, with long runner’s legs and a bite-style like the large cats.

There is something very appealing in this picture: a huge cat-like bear running down prey and dominating the Ice Age landscape. Alas, science cannot be based on drama or romantic notions, and this image of the GSFB gets reexamined from time to time, with other authors coming to different conclusions. Some have pointed out the ambiguity of the limb proportions, or compared the GSFB to its closest living relative, the South American spectacled bear, and concluded that it was primarily omnivorous with a diet rich in plants (Emslie and Czaplewski, 1985).

The question of what the GSFBs were eating, at least, seemed to have been dramatically concluded in a couple of papers during the mid-1990s (Bocherens et al., 1995; Matheus, 1995). Those authors explored the carbon and nitrogen stable isotopes preserved in skeletal material. You are what you eat as differing amounts of these elements are deposited in body tissues depending on their dietary sources, and the isotope data clearly show that the GSFB were eating mostly meat in their diet.

In the most recent paper, Figueirido and colleagues also re-examine Kurten’s cat-like interpretations of the GSFB. For example, they challenge the very notion that the GSFB was short-faced at all. While a casual observation of the skull seems to “bear” that out, they compared the skull and face length with other bears, and it seems that what makes the skull of the GSFB look short-faced is really the depth of the snout and the height of the skull overall, creating an illusion of short-facedness.

Snout lengths relative to skull length in living bears and in the GSFB.

They also ran a number of statistical analyses on the dimensions of the skulls of bears with other carnivores to see if differences in feeding behavior might be teased out this way. Feeding strategy, such as cat-like hypercarnivory or hyena-like bone-crushing, might be visible in the skull proportions. They concluded that the GSFB had a skull shape not like that of a cat, but more similar to modern brown bears (Ursus arctos). Brown bears are omnivorous and will certainly eat meat, but also have a significant amount of plant matter in their diet. So, those authors suggest the skull shape does not support a hypercarnivorous behavior.

Figueirido et al. also examined the claim that the GSFB had extremely long legs. They compared total limb length to overall body weight among modern bears and the GSFB. Their results suggest that the limb length is just what it should be for a bear of the overall size of the GSFB, and not especially long when compared to other bears.

Nothing in science is sacred and I applaud Figueirido et al. for critically looking at past interpretations. However, the answers to our questions continue to elude us. If they are right that the GSFB was not especially short-faced, and that the limbs were not especially long, and the skull was not especially cat-like, none of that really nails down the behavior of this giant species, as they point out. And bears in particular have a tremendous range of feeding adaptations and behaviors that do not fit the mold.

For example, modern bear behavior goes from one extreme represented by the polar bear, which lives on the arctic sea ice and eats almost nothing but seals, to the giant panda living in Asian forests and eats almost nothing but bamboo (but they too will eat meat if given the chance). And between those extremes is a lot of variation. There is really no reason to think that the GSFB was not also variable in its diet and behavior to some degree. But the isotope evidence is hard to argue with at the moment: they seem to have eaten a lot of meat.

The question remains though, how did they get their meat? Did they chase down their prey in long pursuits, or ambush them from short range, or act as the neighborhood bully and chase smaller carnivores from their kills? We don’t yet know but we will keep looking.

Related Posts:
GSFB, a North California Original
Denning Behavior in the GSFB
How Big was the GSFB?
Polar Bear Populations

BOCHERENS, H., S. D. EMSLIE, D. BILLIOU, AND A. MARIOTTI. 1995. Stable isotopes (C13, N15) and paleodiet of the giant short-faced bear (Arctodus simus). Comptes Rendus de l’Acadƒemie des Sciences Paris, 320, serie IIa:779-784.

EMSLIE, S. D., AND N. J. CZAPLEWSKI. 1985. A new record of giant short-faced bear, Arctodus simus, from western North America with a re-evaluation of its paleobiology. Contributions in Science, 371:1-12.

FIGUEIRIDO, B., J. A. PEREZ-CLAROS, V. TORREGROSA, A. MARTIN-SERRA, AND P. PALMQVIST. 2010. Demythologizing Arctodus simus, the ‘short-faced’ long-legged and predaceous bear that never was. Journal of Vertebrate Paleontology, 30(1):262-275.

KURTEN, B. 1967. Pleistocene bears of North America; 2. genus Arctodus, short-faced bears. Acta Zoologica Fennica, 117:1-60.

MATHEUS, P. E. 1995. Diet and co-ecology of Pleistocene short-faced bears and brown bears in eastern Beringia. Quaternary Research, 44:447-453.

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Giant Short-Faced Bear: a Northern California Original

In 1878, James D. Richardson explored Potter Creek Cave in Shasta County, California. He found the skull of a bear beneath several inches of cave dirt, and he sent the specimen to Edward D. Cope, who determined that it was the type specimen for a new species of American “cave bear” (Cope, 1879).


Reconstruction of the Giant Short-faced Bear, Arctodus

When a scientist studies an animal and determines that it is something new to science, they set up a name for it and designate a type specimen. The type specimen, or type, holds a special significance as the “name bearer” for the entire species, and subsequent investigations of that species make reference to the type. They are often kept in special collections within the museums that hold them, or at least given special protection over other specimens. For example, they often are not loaned out as other specimens in the museum collection might be, so there is less risk of damage. (For a description of geologic type sections, see formations).

All too often the type specimens of fossil species have been based on fragmentary material or poor descriptions, making a full understanding of the species more difficult. A famous example of this is the story of the dinosaur Apatosaurus.

Apatosaurus was named by Cope’s rival, O. C. Marsh (Marsh, 1877). Both Cope and Marsh were rushing to describe more fossil species than the other, and their famous rivalry led to shoddy work by both men on occasion. Marsh said the type specimen of Apatosaurus was a “nearly complete specimen in excellent preservation.” However, he only briefly described the vertebrae of this new animal in his haste to publish the new name.

Later, Marsh published the name Brontosaurus, with a few comments on the pelvis and vertebrae of that type (Marsh, 1879). Brontosaurus soon became widely known to the public, and to many, represented the quintessential dinosaur. However, by 1903 Elmer Riggs recognized that Apatosaurus and Brontosaurus were in fact the same species of dinosaur, and since Apatosaurus was named two years before Brontosaurus, that name had priority and was the name that should be used (Riggs, 1903). However, the old name Brontosaurus was in such popular usage that it took many decades for the public to catch on. Now, it seems that every young dinosaur buff knows of this name change and is comfortable with it.

Since the first Short-faced Bear fossil to be recognized in North America was from Northern California, the type specimen, and the name of the bear, Arctodus simus, will be forever linked to the region. This “American Cave Bear” is now known from over 100 localities from Alaska to Mexico, east coast to west (Richards et al., 1996). It was a wide-spread species of the late Pleistocene Ice Age.

What is perhaps most striking about this bear is its size. Arctodus is the largest mammalian carnivore ever discovered. It is larger than any of the modern bears, tigers, or lions by a significant degree. An estimate for the largest Arctodus found to date suggests that if the individual was “lean” it weighed from 1,300 to 1,400 pounds (Nelson and Madsen, 1983). In contrast, a male lion weighs about 450 pounds. (See How big was the GSFB?)

So this imposing carnivore of the Ice Age roamed across North America, and the North State can forever claim it as its own. A full skeletal mount of this beast can be seen in the new Gateway Science Museum at Chico State.

COPE, E. D. 1879. The cave bear of California. American Naturalist, 13:791.

MARSH, O. C. 1877. Notice of new dinosaurian reptiles from the Jurassic Formation. American Journal of Science, 14:514-516.

MARSH, O. C. 1879. Notice of new Jurassic reptiles. American Journal of Science, 18:501-505.

NELSON, M. E., AND J. H. MADSEN, JR. 1983. A giant short-faced bear (Arctodus simus) from the Pleistocene of northern Utah. Transactions of the Kansas Academy of Science, 86(1):1-9.

RICHARDS, R. L., C. S. CHURCHER, AND W. D. TURNBULL. 1996. Distribution and size variation in North American short-faced bears, Arctodus simus, p. 191-246. In K. M. Stewart and K. L. Seymour (eds.), Palaeoecology and Palaeoenvironments of Late Cenozoic Mammals: Tributes to the Career of C.S. Churcher. University of Toronto Press, Toronto.

RIGGS, E. S. 1903. Structure and relationships of opisthocoelian dinosaurs. Part
1: Apatosaurus Marsh. Field Columbian Museum, Geological Series, 2:165-196.

Related Posts:
How big was the GSFB?
Denning behavior
GSFB reexamined

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