Above: painting reconstruction of Pleistocene San Francisco Bay.
From Wikipedia: Kleptoparasitism or cleptoparasitism (literally, parasitism by theft) is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food.
To what degree Arctodus Simus was a true carnivore has not been resolved, however, most researchers agree that this enormous bear was well suited for defending and scavenging large mammal carcasses.
Short-faced bears were primarily scavengers of widely dispersed large mammal carcasses and were simultaneously designed both for highly efficient locomotion and for intimidating other large carnivores. This allowed Arctodus to forage economically over a large home range and to seek out, procure, and defend carcasses from other large carnivores.
Matheus, Paul. 1995. Diet and co-ecology of Pleistocene short-faced bears and brown bears in eastern Beringia. Quaternary Research 44(3):447-453.
Despite these uncertainties we hypothesize that A. simus would have been more carnivorous than other southeastern bears and therefore filled a different ecological niche than did T. floridanus and U. americanus. Its primary competitors in the large carnivore guild of the southeast would have been dire wolf (Canis dirus Leidy, 1858) and large felids like Panthera atrox (Leidy, 1853), Panthera onca (Linnaeus, 1758) and Smilodon fatalis (Leidy, 1868). The much larger body size of A. simus would have provided an advantage in disputes over carcasses. The paleodiet and ecological relationships of late Pleistocene bears could be further analyzed with isotopic and microwear analyses.
BW Schubert, RC Hulbert Jr. 2010. Paleontological Soc, Giant short-faced bears (Arctodus simus) in Pleistocene Florida USA, a substantial range extension. Journal of Paleontology; 84: 79-87.
In short, we suggest that A. simus may be best envisaged as a colossal omnivore whose diet probably included varying amounts of meat according to food availability. Of course, we do not wish to imply that A. simus did not prey occasionally on bison, deer, or ground sloths, nor that it did not scavenge the carcasses left over by the hypercarnivores such as saber-tooth cats (Smilodon fatalis and Homotherium serum), giant lion (Panthera atrox), and dire wolf (Canis dirus). We simply affirm that A. simus did so in a similar manner as some North American populations of brown bears (e.g., Alaska and Yukon) currently do so.
We do agree with Matheus (1995) that the huge body size of this extinct bear probably facilitated kleptoparasitism of ungulate carcasses.
Figueirido, Borja, Pérez-Claros, Juan A., Torregrosa, Vanessa, Martín-Serra, Alberto and Palmqvist, Paul(2010) 'Demythologizing Arctodus simus, the 'Short-Faced' long-legged and predaceous bear that never was', Journal of Vertebrate Paleontology, 30: 1, 262 — 275.
The dental and skeletal morphologies of A. africanum and A. simus suggest that these extinct ursids were not active predators, but their diet did include a large amount of animal material, which was obtained by scavenging. The rest of their diet consisted of coarse foliage, which was obtained by unselective grazing.
Sorkin, B. (2006). Ecomorphology of the giant short-faced bears Agriotherium and Arctodus. Historical Biology: A Journal of Paleobiology 18: 1–20.
Post by grrraaahhh on Mar 24, 2011 13:09:00 GMT -9
Arctodus Simus as Scavenger/Key Text Extracts:
"Our interpretation is compatible with the proportions of the limbs. Arctodus simus was not adapted for speed, or for jumping (Emslie and Czaplewski 1985). These limbs and locomotion are satisfactory for a scavenger."
"The body size in Arctodus simus is also normal for scavengers."
"It may be that the corpses of Pleistocene megafauna (mammoths, and other large ungulates) fed this large Pleistocene bear."
"A plains and grasslands distribution negates the necessity (and probability) of long limbs as an adaptation to pulling down high grass, bushes and other vegetation. It may indicate an adaptation to travel in grasslands, plus an adaptive advantage in the dismemberment of the carcasses of megaherbivores. If it is advantageous for predatory carnivores to hide in high grass, it would have been necessary for a scavenging Arctodus simus to be able to see over the grass. Arctodus simus possibly ranged with the herds of mammoth, bison, and other large herbivores, looking for the converging of carrion-feeding birds (vultures, condors, teratorns) as a clue to carcass locations."
"Such a strategy probably required a wide home range in order to exploit a sufficient number of carcasses."
"If we suppose that Arctodus simus was a scavenger, it would be normal for it to have been sympatic with Ursus americanus and Ursus arctos. There may not have been competition for scavenging with the smaller bears, although the mighty Arctodus simus sometimes may have fed from the kills of the smaller bears or the big cats (Panthera, Smilodon)."
Baryshnikov, G., Agenbroad, L.D., Mead, I.J. 1994. Carnivores from the mammoth site, Hot Springs, South Dakota.
Recent video documentary (National Geographic: Prehistoric Predators GSFB) follow up to the South Dakota, 'Hot Springs' site featuring Larry Agenbroad, Paul Matheus, Greg McDonald and Chris Shaw.
Post by grrraaahhh on Mar 24, 2011 13:22:22 GMT -9
Conforming to the Hot Springs findings which supports the position of A.simus as a scavenger, there is the 1985 herbivorous model advanced by Steven D Emslie and Nicholas J Czaplewski to factor:
We prefer to believe that A.simus was primarliry herbivorous, as T.ornatus, but also may have been an opportunistic predator and scavenger with bone-crushing capabilities.
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 and Soibelzon (2009) proposed that A. angustidens had an omnivorous diet composed of a variety of components, but with a predominance of animal remains. This does not imply that active hunting was the unique strategy for feeding, since its large size and great power may have permitted the bear to fight for prey killed by the other large Pleistocene carnivores (e.g., the sabertooth cat Smilodon populator Lund, 1842). Scavenging megaherbivore carcasses was probably another frequent way of feeding for A. angustidens (Soibelzon, 2002a); a similar strategy has been invoked for Arctodus simus (see Schubert and Wallace, 2009 for discussion).
Leopoldo H. Soibelzon and Blaine W. Schubert (2011) The Largest Known Bear, Arctotherium angustidens, from the Early Pleistocene Pampean Region of Argentina: With a Discussion of Size and Diet Trends in Bears. Journal of Paleontology: January 2011, Vol. 85, No. 1, pp. 69-75.
As Schubert and Wallace report, however, there is now evidence that at least two large carnivores lived in the same area at the same time. The most direct evidence comes from a partial right lower jaw bone with a molar tooth still embedded in it. It belonged to a very large bear, and the details of the teeth and shortening of the jaw (indicating a short face) allowed the researchers to narrow down their list of candidates to Arctodus simus, popularly known as the "short-faced bear." In fact, compared to other skeletons from this species, this individual from Virginia appears to have been especially snub-nosed.
A mammoth heel bone (calcaneus) damaged by a predator's canine. The arrow indicates the puncture mark. From the Boreas paper.
The second line of evidence comes from mammoth bones found at the same site. The scientists describe several parts of a mammoth ankle and foot that were chewed on by carnivores. The question is, "What kind of carnivores did the damage?"
One of the bones, the calcaneus (or heel bone) was bitten completely through by a predator with a large canine tooth. Only two known Late Pleistocene carnivores were large enough to inflict this type of damage; the American lion (Panthera leo atrox) and the short-faced bear. As big cats typically avoid chewing on bones, however, the bear is the more likely culprit.* This is consistent with the results of radiocarbon dating carried out on the mammoth bones and the bear jaw. The two animals lived within about 340 years of each other, so it is likely that both coexisted in the same place at the same time.
*[The authors point out, however, that American lions are often found with broken teeth. This suggests that they more regularly bit through bone and chewed hard parts of carcasses than their modern relatives in Africa and India. Though no remains have been found of the American lion at the Saltville site, it cannot be ruled out as a suspect.]
Above: Painting reconstruction of Dirk-tooth cats (Homotherium serum) attacking a Colombian mammoth herd (Mammuthus Columbia), but a larger predator joins in: a Giant short-faced bear (Arctodus simus). Southern California Pleistocene. Note: additional artist artwork along with the artist's web page is provided in the Gallery section.
Whether or not the species maintained this carnivory across their range has not been resolved, but isotopic analyses are underway to test this. Although some debate exists on the carnivorous strategy of A.simus (Kurten, 1967; Matheus, 1995, 2003 ), most researchers agree that this enormous bear was well suited for defending and scavenging large mammal carcasses (Emslie and Czaplewski, 1985; Voorhies and Corner, 1986; Baryshnikov et al., 1994; Matheus, 1995, 2003; Sorkin, 2006; Schubert and Wallace, 2009).
Blaine W. Schubert (2010). Late Quaternary chronology and extinction of North American giant short-faced bears (Arctodus simus).
Why did Arctodus Simus attain such large body size? As it relates to scavenging or kleptoparasitism there is correlation - here, plans are to examine the relating position advanced by Paul E. Matheus (1995, 1997).
Kleptoparasite has a horrible sound to it. This brings up one of my pet peeves. Flesh eatting mammals are seperated as predator or scavenger, even though most are both. There is a difference between a scavenger and an usurper. Jackals and vultures are true scavengers. They eat the leftovers after the true predator has had his fill. An usurper takes the kill from the true predator; big difference.
Above: From the BBC Prehistoric America documentary, an adult (mature) Giant Short Faced Bear drives off two American lions from a mammoth carcass. While the debate over the GSFB diet continues, the scientific literature consensus is clear about the capacity of the GSFB (as illustrated in popular culture and documentary) to acquire and defend animal material from other predators for its dietary consumption.