Friday, July 9, 2010

The Atlas Bear (Ursus crowtheri), a Closer Look at Africa's Only Bear


Let us travel to the Maghreb, north of the Sahara Desert, to the high Atlas Mountains of Morocco. In many places, these austere, celestial heights still remain relatively unblemished and pristine, and contain a wealth of superb natural treasures.

The climate of North Africa is varied but more or less parallels the natural conditions found on the other side of the Mediterranean Sea – a stark, rocky, and arid wilderness of high, dry plains, open, mixed woodlands, and alpine expanses. Remarkably, at the narrowest point in the Strait of Gibraltar, North Africa is separated from Spain by only 7.7 nautical miles of seawater (14.24 km). And thus, to no marginal extent –and perhaps expectedly- North Africa’s biological composition is characterized by an exceptional mixture of both African and European floras and faunas.

This place was once the haunt of the outstanding Barbary Lion (Panthera leo leo), a great cat of superlative splendor and form, which disappeared from the continent sometime during the course of the early to mid 20th century. A smaller pantherine counterpart of this region –the secretive Barbary Leopard (Panthera pardus panthera) - managed to cling precariously to existence for some decades longer than the lion, and has itself disappeared perhaps only within this last ten years or so. There is still some hope that these incredible cats lurk like ghosts in the far reaches of the mountains, but they have not been seen or otherwise detected for a discouraging number of years. Many people fear that the Atlas Mountains have finally lost two living jewels that may never be obtained again.
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But there was another living jewel, a very unusual creature –and seemingly out of place for its kind- which disappeared from northern African probably about one century before the lion and the leopard. The creature was unusual for several reasons, the first reason was that it was a bear –the only native kind naturally present on the vast African continent within recent history, and the second, that it may have in fact been a distinct species apart from the ones we are now familiar with.


Megafaunal Maghrebi Carnivores The three greatest carnivores of the Maghreb are now extinct. The Barbary Lion (Panthera leo leo) was the greatest among them and the greatest among all lions, the male manifested an impressively developed mane which grew black and thick and extended all the way down the length of his belly; such lions would have hunted the Red Deer of the Atlas as well as wild boar, Barbary Sheep, Mouflon and gazelle. It would appear as though many captive lions today are descended from the Barbary race; be that as it may, the race remains functionally extinct. The Atlas Bear (Ursus arctos crowtheri), without a doubt unique among Ursines, cannot be resurrected to its former condition. The Barbary Leopard (Panthera pardus panthera) on the other hand, may still lurk like a shadow in the mountains, though verified sightings have not been made in over a decade. It appears as though the great cat was not substantially different enough genetically from its abundant counterparts south of the Sahara to be considered a distinct subspecies -though it possessed certain physical traits unique among leopards of the region.
To this day, not much is known about the Atlas Bear, as it is rumored that the very last among them were hunted to extinction sometime during the course of the late 19th century. No skeletal remains or pelts were ever preserved for study while the living animals were apparently kept by European zoos, and most of what is known about its physical appearance and morphology is derived from scant observations recorded by French scientists in the early 1800s (though, as later discussed, Brown Bear subfossils have been found at various sites in North Africa in recent decades). Its Latin name –though sometimes disputed- is Ursus arctos crowtheri, owing to the reasonable presumption that it was a race of Brown Bear, Ursus arctos.

Just how modern bears ended up in Africa is a riddle in itself. It is known that primitive bears, such as the large predatory Agriotherium, were present in the African ecosystems during the Pliocene–Pleistocene epochs ~6-2.5 million years ago, evidently of Eurasian origin.2 Yet Agriotherium belonged to a branch of bear evolution quite apart from modern bears, which are comprised of about 3-4 recognized genera: Helarctos, Tremarctos, Ursus, and sometimes Melursus respectively.

Since the Atlas Bear was certainly a species of the genus Ursus, the question of its origin must be traced back to a time within the last 5 million years or so and probably more realistically during the course of the late Pleistocene, when Ursus arctos (its suspected forerunner) radiated into it’s many splendid forms and gave rise to Ursus maritimus (the Polar Bear).

Because there is very little doubt about the closeness in relation between the Brown Bear and the Atlas Bear (regardless of whether or not they are different species), and because the genus Ursus most certainly arrived in northern Africa sometime during the late Pleistocene, it can be fairly concluded that the Atlas Bear’s ancestors arrived from either one of two –or a combination of both- major geographical regions: 1) by way of a southward expansion from Mediterranean Europe or 2) by way of a westward expansion from the Levant and the greater part of the Middle East (what is now present-day Israel).Today, the nearest population of living Brown Bears within proximity to the former range of the Atlas Bear lies in the Pyrenees Mountains of northern Spain.3 East, in Syria and Lebanon (the other probable geographical source of African bears), there is a very unique and special race of Brown Bear known as the Syrian Brown Bear (Ursus arctos syriacus) that also inhabits certain regions of the former Soviet Union.

With all that being said however, and in light of North Africa’s rather significant proximity to the southern tip of the Iberian Peninsula, it is tempting and perhaps more reasonable to assume that the Atlas Bear had its immediate origins in Europe. It is also tempting to believe that sea levels dropped and regularly exposed land-bridges between Europe and Africa at the Strait of Gibraltar during the successive ice ages –essentially creating a walk in the park for the transcontinental migrations of large terrestrial mammals. But is it a safe assumption -strictly from a geological point of view?

The Mediterranean Sea, notwithstanding Atlas Bears, is a scientific enigma in itself, and while the Strait of Gibraltar is narrow, it substantially deep enough to have never been a land bridge during the recent ice ages. It is otherwise believed that North Africa and Europe haven’t been connected for at least 5 million years.

Yet there is another quite obvious possibility to explain the origins of the Atlas Bear regardless of land bridges or dried up seas...

Within the Atlas Mountains and the greater part of the Maghreb there live a considerable number of other terrestrial mammals that are more characteristically Eurasian (not to mention the great abundance of Ibero-North African flora). The first is the Red Deer (Cervus elaphus barbarus) –Africa’s only native deer- followed by the Wild Boar (Sus scrofa algira), the Mouflon (Ovis aires orientalis or sometimes Ovis orientalis), the now extinct North African Aurochs (Bos primigenius mauretanicus), the Red Fox (Vulpes vulpes), the Wildcat (Felis silvestris lybica), the Least Weasel (Mustela nivalis), and the European River Otter (Lutra lutra). Most of these animals, though they are racially distinct from their counterparts in Europe and Asia, doubtless were descended from migrants of Europe or the Middle East during the Pleistocene or recent Holocene epochs. Correspondingly, there are also a number of terrestrial mammals present on the Iberian Peninsula which are more characteristically Maghrebi, such as the Algerian Hedgehog (Atelerix algiris), the Common Genet (Genetta genetta), and the Egyptian Mongoose (Herpestes ichneumon). It is also worth mentioning that the Barbary Macaque (Macaca sylvanus), native to North Africa and the Atlas Mountains, is also native to the Rock of Gibraltar on the southernmost tip of Spain –it is the only European primate aside from human beings.


Possible Geographic Origins of the Atlas Bear The Iberian Peninsula via the Strait of Gibraltar, or the Middle East via the Levant and Egypt.
So, how might all of these animals have arrived to North Africa if not by land? By sea of course! It is also completely within the realm of possibility that such populations of animals were established (or genetically augmented) by a successive colonization of dispersing individuals who swam across the strait’s 7.7 miles of seawater. This is especially not hard to believe when considering the aquatic versatility of Brown Bears in other parts of the world. Some insular Brown Bears, such as those once found in Britain, Ireland, and Japan, most certainly populated those landmasses when they were connected to the continent by way of exposed land bridges during the Ice Ages.

In any case, bears –and a score of other more characteristically Eurasian animals- ended up in North Africa, whether by land bridges in the Ice Age, dried up seas, the comparatively simpler route of migration from the Levant to North Africa, human introduction, or swimming. But what can be said about the bear itself besides its mysterious origin? Was it truly a Brown Bear? Or was it another species in its own right? And if it was, could its origin still be traced back to Pleistocene Europe? Pleistocene Europe, while home to Ursus arctos, was also home to the famous Cave Bear (Ursus speleaus) as well as the Etruscan Bear (Ursus etruscus), which is thought to be the ancestor of all bears classified within the genus Ursus and which persisted amongst its evolutionary descendants up until 11,000 years ago.4

Recent studies have indicated that there was a surprising size range in Maghrebi Bears. However, it is generally accepted that they were relatively small -being roughly the size of the American Black Bear. The Atlas Bear was certainly not descended from the Cave Bear therefore, but more likely from the Brown Bear, the Etruscan Bear, or an intermediate form. The two subspecies of Brown Bears that have been uncovered from Pleistocene fossil deposits of northern Africa have been named and identified as Ursus arctos faidherbi and Ursus arctos larteti. The recent presence of these bears in African ecosystems seems to strongly indicate that the Atlas Bear was, in all likelihood, descended from Ursus arctos after all, but other clues as to its true origin can be further derived from methods of modern science.

Recent genetic studies which have traced the mitochondrial DNA of Atlas Bear specimens have revealed quite a lot of interesting information, both in regards to the proper classification of the bear as well as its likely ancestry and geographical origin. Yet the implications of some of these finds are just as inconclusive and mysterious as ever, perhaps invoking more questions than answers.

To begin with, modern Brown Bears are divided into five mitochondrial lineages or clades, which are listed in the box below. These lineages correlate fairly consistently with the geographical distributions of all of the major subspecies of extant Brown Bears now recognized in the modern world.

Interestingly, these studies have concluded that the Brown Bears of the Maghreb were not a genetically homogeneous population and that there were at least two mitochondrial lineages of Brown Bears coexisting in North Africa up until the beginning of the first millennia AD. “…two of the most recent Brown Bear remains ever found in Africa (those found in the Akouker Cave in Algeria, dating to ~326 AD and ~456 AD respectively), shows the presence of the already recognized Clade V haplotype on the continent” (Calvignac, 1967), further suggesting that –however possible- there was indeed a genetic flow into Africa from Europe by way of the Strait of Gibraltar (the Akouker bears revealed mitochondrial sequences almost identical to that of the living Iberian bears of Cantabria). Yet, the specimens which were collected from the Takouatz Cave of Algeria and the El Ksiba Cave of Morocco (3 samples dating ~5,339-7,614 BC from Takouatz and one sample dating ~726 AD from El Ksiba) revealed a very different composition, and appeared to be of a strongly divergent lineage previously unrecognized among the Brown Bear clades. All five mitochondrial lineages of extant Brown Bears can be classified into one large haplogroup, but this sixth clade appears to be different enough to be categorized as an ancient offshoot –a basal clade whose origins were either developed uniquely in Africa or simply lost everywhere but North Africa due to lineage sorting during the late Pleistocene.

Perhaps what is most remarkable about the revelation of Clade VI apart from the fact that it is now extinct is that its degree of genetic deviation –evidently ancient- is substantial enough to perpetuate the debate of the proper classification for Maghrebi Brown Bears. “It’s divergence from all other living Brown Bears is striking: at the maximum 11.3% for the mtCR sequences and 5.9% for the cyt b ones, values which are to compare to the minimum values of divergence between the Brown Bear and its now-extinct sister species (the Cave Bear), respectively, 9% for the mtCR and 5.7% for the cyt b sequences” (Calvignac, 1968).

Thus, it may be fairly surmised that with at least two very different Brown Bear populations living contemporaneously in North Africa up until the early part of the first millennia AD, the animal generically labeled as the Atlas Bear may have in fact been a genetic fusion of mixed ancestry and geographical origin (coming from both the Iberian Peninsula and the Middle East at varying stages and to varying degrees throughout the ages). Therefore, the extant though critically endangered Syrian Brown Bear (U. arctos syriacus) which still exists in the Levant5, as well as the few remaining Pyrenean Brown Bears left in northern Spain, may share close relations with the now extinct Atlas Bear.6

Aside from new and compelling genetic studies, there are certain known anatomical differences in the morphology of at least some of the Maghrebi bears, which further elicit the understandable suspicion that they were in fact a separate species apart from Ursus arctos. Yet it may be stated that modern specimens of Atlas Bears are very few and consist entirely of fragmented subfossils found in caves –the most recent of which dates to ~726 AD.

A general appearance of the bear has been pieced together from numerous sources, though how standard the following description was for the whole population is largely guesswork.

As previously mentioned, the Atlas Bear –short-faced, shaggy, and small- was generally about the size of the American Black Bear (Ursus americanus), although more heavily muscled. This would have probably placed its typical weight range anywhere between 200-500 lbs. for males, and 100-300 lbs. for females (also assuming they were as dimorphic as other living species of bears). Their fur was wooly and thick, dark brown to blackish in coloration, with belly fur and undersides lighter and of a rufuous-orange complexion. The claws of the Atlas Bear were apparently quite short, which seems to indicate that –given its smaller size- it may have been capable of climbing trees.

Some might claim that further clues to the physical appearance of the bear can be partly derived from mosaic images in Roman art, which some researchers have identified as probable ‘Atlas Bears’ (though how valid these claims are can really only be verified if the images are truly North African).7 From these few published images, it appears as though the animal retained some characteristics that are very unique to Brown Bears –such as the defining shoulder hump, the upturned, concave nose, and the smaller, rounded ears.

It is believed that Atlas Bears probably fed mostly on ripe acorns (such as those belonging to the Algerian Oak), nuts, fruits, succulent roots, edible foliage, and occasional animal protein (a typical bear diet). A fairly accurate blueprint of the Atlas Bear’s diet could be derived from study of dental tooth-wear patterns as well as trace chemicals found within the bone tissue, but it appears that no such work has been either conducted or extensively published.

Ursus arctos crowtheri –once present in the vast territory spanning the region from Morocco to Libya- has all but vanished, and Berber country has no more bears.

What happened to this superb and unique animal? What or whom is responsible for its disappearance? It was likely a combination of several known factors which led to its extinction.

The depletion of the Atlas Bear (as well as the extinction of the Carthaginian Elephant Loxodonta africana pharaoensis and the European Lion Panthera leo tartarica) began with the expansion of the Roman Empire, which captured bears and other animals to be used as battle fodder for the savage entertainment of its gladiatorial arenas. Over the centuries, thousands upon thousands of bears (from Europe, North Africa, and the Middle East) were seized from the wilderness and pitted against gladiators, lions, tigers, and other animals –all of them routinely starved to induce desperation and increase natural aggression. It was a brutal and perhaps unfair end for an animal, which, in all truth, would have otherwise spent its comparatively less violent life eating acorns and honey in the mountains.

It has been speculated that at least some Atlas Bears may have in fact been ‘feral’ bears exported from Europe, and that the presence of bears in Africa may be partially if not entirely explained by an accidental or purposeful introduction by the Romans and Carthaginians who used the bears in battle arenas. This could at least be one possible explanation for the presence of the Clade V haplotype in some specimens, however, with the recent and profound discovery of Clade VI, and with the earlier presence of Ursus arctos faidherbi and Ursus arctos larteti in the Maghreb during the late Pleistocene, it may be fairly stated that the majority of these bears had become native to North Africa due to the natural dispersion of the species in ancient times (further verified by 14 C tests of the Takouatz bears, which predated the Romans by 5-7 millennia).8

After Roman cultural-political influence diminished and eventually faded out of northern Africa and Morocco, the Atlas Bears were further reduced by natural environmental changes which dried up their natural woodland habitats and expanded the desert. Continued over-hunting and over-harvesting by Berber tribesmen, Arabs, and finally pressure from European zoo collectors in the centuries that followed pushed the bear to the brink of extinction. The last known Atlas Bear was probably killed in the Tétouan Mountain Range in the late 19th century.

If indeed human beings were the greatest catalysts in the extinction of the Atlas Bear, what more can or should be said, but that our generation has been impoverished by the unnecessary loss of this very unique and very mysterious animal.

BROWN BEAR SUBSPECIES (Ursus arctos)
1. Common English Name (Latin Name) NATURAL RANGE PRIOR TO 1800, notes
Extinct
•Several dozen suggestions have been made for the number of Brown Bear subspecies, for simplicity’s sake, and in light of their uniqueness, 15 are listed here.
1. Eurasian Brown Bear (Ursus arctos arctos) EUROPE AND ASIA
2. Atlas Bear (Ursus arctos crowtheri) NORTH AFRICA, U. crowtheri by some authors
3. Syrian Brown Bear (Ursus arctos syriacus) MIDDLE EAST, SW ASIA
4. Himalayan Brown Bear (Ursus arctos isabellinus) HIMALAYAS, CENTRAL ASIA
5. Tibetan Blue Bear (Ursus arctos pruinosus) HIGH TIBETAN PLATEAU
6. Gobi Bear (Ursus arctos gobiensis) MONGOLIA, similar to the Grizzly Bear, inhabiting the Gobi Desert
7. East Siberian Brown Bear (Ursus arctos collaris) EASTERN SIBERIA
8. Ussuri Brown Bear (Ursus arctos lasiotus) USSURILAND
9. Kamchatka Bear (Ursus arctos beringianus) KAMCHATKA PENINSULA, paralleling the Kodiak Brown Bear and other coastal Alaskan Brown Bears in size and behavior, the two populations are genetically very closely related and are separated by only a marginal distance across the Bering Sea.
10. Hokkaido Brown Bear (Ursus arctos yesoensis) JAPAN
11. Kodiak Bear (Ursus arctos middendorffi) COASTAL ALASKA, on average, this is the largest bear in the world, only exceeded in size by exceptionally large male polar bears, which are also longer and taller by comparison.
12. Baranof Island Bear (Ursus arctos sitkensis or U. a. dalli) ADMIRALTY, BARANOF, and CHICHIGOF ISLANDS ALASKA, curiously, genetic tests have indicated that these bears are more related to Polar Bears (Ursus maritimus) than to other Brown Bears (though they are superficially more similar to the latter). Baranof Island is home to one of the highest densities of Brown Bears in North America.
13. Grizzly Bear (Ursus arctos horriblis) NORTH AMERICA WEST OF THE MISSISSIPPI RIVER, the grizzly bear –once a common animal- has been exterminated from most of its former range in the continental United States, save certain wilderness areas in Wyoming, Montana, and Idaho (and of course, Alaska). Most grizzlies now live in western Canada and Alaska.
14. California Grizzly (Ursus arctos californicus) PACIFIC COAST NORTH AMERICA, CALIFORNIA
15. Mexican Grizzly (Ursus arctos nelsoni) MEXICO, SW UNITED STATES, Once inhabiting northern Mexico, New Mexico, and Arizona, this bear went extinct sometime during the course of the late 1960’s, it’s last strongholds were in the states of Chihuahua and Sonora

FOOTNOTES

1. It is suspected that the Barbary Lion’s irreplaceable racial composition remains in tact and pure in some captive lions, which are believed to be descended from lions caught generations before in northern Africa. Many of these male individuals also manifest a marked degree of extensive mane development –a defining characteristic of mature male Barbary Lions, which grew very dark manes that frequently extended all the way down the length of the belly. There has been some talk of initiating a selective breeding program which ‘breeds back’ the Barbary Lion from captive individuals that exhibit favorable traits. A subsequent reintroduction program has also been discussed. The Barbary Leopard’s extinction is not absolute; it may still survive in small numbers in Morocco, Algeria, and possibly Egypt. The Barbary Leopard had thicker, darker fur than its living counterparts in Subsaharic Africa.

2. Agriotherium –existing from the Miocene-Pleistocene epochs of North America, Eurasia, and Africa ~13.6-2.5 million years ago- was similar in size and form to the later Arctodus (the giant Short-faced Bear) and possessed powerful jaws that had the capacity to crush bone. Agriotherium also retained some very primitive, dog-like characteristics that distinguished it from other bears which existed and evolved during the same time period.

3. Unfortunately, these Pyrenean bears are only a remnant population of Eurasian Brown Bears which once existed in strong numbers throughout the Iberian Peninsula and the rest of Europe, they are believed to number only a paltry 14-18 bears, with a lack of breeding females.

4. The Cave Bear (Ursus speleaus) and the Brown Bear (Ursus arctos) are thought to have diverged 1.4-1.2 million years ago, much longer before the divergence of Ursus arctos and Ursus maritimus.

5. It is worth mentioning that the Syrian Brown Bear’s natural range once extended into the northeastern-most corner of modern day Egypt (they have been exterminated throughout most of their historical range but exist in small numbers in Iran, Iraq, and Turkey); thus, the Atlas Bear was not technically Africa’s ‘only’ bear in recent millennia. It is worth mentioning that none of the haplotypes unique to North African bears were found in the living population of Middle Eastern bears –according to a recent study. Still, this does not entirely rule out the likelihood that the Atlas Bears had ancestral origins in the Middle East during the Pleistocene, as the living sample population of Middle Eastern bears are comprised of very few –though genetically diverse- individuals. This could also further support the possibility that the Clade VI haplotype was developed solely in Africa, where it evidently never left.

6. These findings reveal that the evolutionary origin of North African Brown Bears is complicated and puzzling. It may also be stated that with the strong genetic divergence of the bears which exhibited the previously unknown Clade VI haplotype, it can also be reasonably speculated that some Maghrebi bears could be justly regarded as a unique species apart from Ursus arctos. Whether these two populations interbred and mixed genes successfully is not yet known, and it throws the classification of the Atlas Bear into further confusion. Were North African Brown Bears one subspecies, two subspecies, one species, or two different species? For now, all that can be safely surmised is that the Atlas Bear was genetically heterogeneous and therefore likely had its racial origins in several geographical sources –namely, Europe and the Middle East.

7. Such claims are truthfully invalid if these mosaic images were encountered in Europe. Most of the bears used in the gladiatorial games were logically of European or West Asian origin, since these were the most immediately available and the easiest to transport. There is little doubt that the Atlas Bear was a victim of the Roman battle arenas, but just how much it was significantly depleted by the Romans and Carthaginians for this purpose is largely a historical assumption. It is more likely that the bears were killed outright and over-hunted in the wilderness by various groups of North African peoples in the recent millennia (including the Romans and Carthaginians).

8. It has been questioned sometimes whether the Atlas Bear ever existed at all, the argument in recent decades was based off of the fact that there are no skins or bones preserved for study (deceased zoo animals in the 1800s were apparently never skeletonized or archived). However, as previously detailed, Maghrebi Brown Bear subfossils dating to millennia within the recent Holocene have confirmed that the Atlas Bear did in fact exist, it is from these few ancient bones that the most accurate information on morphology, diet, and genetic composition can be derived.

REFERENCES

Calvignac, Sébastien., Hughes, Sandrine., Tougard, Christelle., Michaux, Jacques., Thévenot, Michel., Philippe, Michel., Hamdine, Watik., Hänni, Catherine. “Ancient DNA Evidence for the Loss of a Highly Divergent Brown Bear Clade during Historical Times.” Molecular Ecology 17 (2008): 1,962-970. 7 June 2010 <http://www.sebastiencalvignac.fr/downloads/calvignac2008atlasbrownbear.pdf>

Calvignac, Sébastien., Hughes, Sandrine., Hänni, Catherine. “Genetic Diversity of Endangered Brown Bear (Ursus arctos) Populations at the Crossroads of Europe, Asia, and Africa.” Diversity and Distributions (2009): 1-9. 7 June 2010
Hamdine, Watik., Michaux, Jacques., Thévenot, Michel. “Recent History of the Brown Bear in the Maghreb.” CR Acad Sci III. Jul. 1998: 565-70. 7 June 2010 <http://www.ncbi.nlm.nih.gov/pubmed/10877599>

Loreille, Odile., Orlando, Ludivoc., Patou-Mathis, Maryléne., Philippe, Michel., Taberlet, Pierre., Hänni, Catherine. “Ancient DNA Analysis Reveals Divergence of the Cave Bear, Ursus speleaus, and Brown Bear, Ursus arctos, lineages.” Current Biology Volume 11, Issue 3, 6 Feb (2001): 200-203. 7 June 2010

Dobson, M. “Mammal Distributions in the Western Mediterranean: The Role of Human Intervention.” Mammal Review Volume 28, No. 2 (1998): 77-88. 7 June 2010 <http://www.egs.mmu.ac.uk/users/shoon/eg2116/WebDocs/mkd-mammal.pdf>

Straus, Lawrence Guy. “Africa and Iberia in the Pleistocene.” Quaternary International Volume 75, Issue 1, Jan 2001: 91-102. 7 June 2010

Bonfiglio, Laura., Mangano, Gabriella., Marra, Antonella Cinzia., Masini, Federico., Pavia, Marco., Petruso, Daria. “Pleistocene Calabrian and Sicilian Bioprovinces.” Geobios Volume 35, Supplement 1, Dec 2002: 29-39. 7 June 2010

Day, D., The Doomsday Book of Animals: A Natural History of Vanished Species. New York: Viking, 1981.

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Attenborough, D., The First Eden: The Mediterranean World and Man. New York: Little, Brown & Company, 1987.

MacDonald, David W., The Princeton Encyclopedia of Mammals. Princeton, NJ: Princeton University Press, 2006.

Ellenberger, W., and Baum H., H. Dittrich. An Atlas of Animal Anatomy for Artists. Second Revised and Expanded Edition, New York: Dover Publications, Inc., 1956.

Burt, William Henry., Grossenheider, Richard Philip. Peterson Field Guides: A Field Guide to the Mammals of North America north of Mexico. 3rd Ed. New York, NY: Houghton Mifflin Company, 1980.

SUGGESTIONS FOR FURTHER READING

GHOST GRIZZLIES by David Peterson
THE FIRST EDEN: THE MEDITERRANEAN WORLD AND MAN by David Attenborough