Allen Wilson
7-29-08
Dr. McCall

Taxonomy
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Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
• Suborder: Caniformia
Family: Ursidae
• Subfamily: Ailurinae (Panda bear)
Subfamily: Ursinae (The other 7 species of bear

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Evolutionary Divergence of
Ursidae
Origins of this family can be traced to Paractis
(very small, skull 7 cm.)
Paractis first occurred in North America during the Late Eocene, but not found in Eurasia and
Africa until Miocene
However, suggestions leads to speculation that earlier ursids in Asia, during Eocene, gave rise to
Paractis in North America, although no fossils of
Paractis have been found in East Asia
This migration may have occurred via a major sea-level lowstand 37 million years ago

Evolution of Ursidae (cont.)
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The most primitive ursid was Cephalogale, a raccoon-sized, dog like creature
Cephalogale first appeared in the
Oligocene to early Miocene in Europe
Cephalogale gave rise to early bears
(Ursavus) in Europe
Ursavus radiated into Asia and gave rise to the first true bears (Ursus) in Europe or
Asia about 5 million years ago

Cephalogale jaw

More Evolution!
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Ursids became very diversified in the
Oligocene in Asia
Four species are found in Asia correlating to this time, three are found commonly in
Europe, but one is endemic to Asia
(suggesting speciation)
Migration of most early ursids to North
America is suggested to occur during the late Oligocene and early Miocene
True bears (Ursus) migrated during the
Pliocene about 4 million years ago

Ursidae family tree

Ursidae Genera
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Tremarctos including Spectacled bear
Ailuropoda including the Giant Panda
Ursus including American Black Bear,
Asiatic black bear, polar bear, brown bear, Malaysian sun bear, and sloth bear

Urisidae phylogeny

Species of Ursidae family
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· American Black Bear (Ursus
americanus)
· Asiatic Black Bear (Ursus thibetanus)
· Brown bear (Ursus arctos)
· Giant Panda (Ailuropoda melanoleuca)
· Polar Bear (Ursus maritimus)
· Sloth Bear (Melursus ursinus)
· Spectacled Bear (Tremarctos ornatus)
· Sun Bear (Helarctos malayanus)

Giant Panda
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Ailuropoda diverged from the Ursavus group between 18-22 million years ago
The Giant Panda was the first modern bear to arise from this group
The range of this group exhibits little migration from their evolutionary home in
Asia, probably due to a localized food source
Only 700-1000 exist in wild

Giant Panda Range

Giant Panda

Sloth Bears
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Ursis ursinus radiated from the other ursidae family members about 7 million years ago
The oldest ursis bear, and no surprise that it has the farthest east distribution, not ranging much from its ancestral home

Sloth Bears

Malaysian sun bear
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Smallest of all the bears, consistent with Bergmann’s rule
Polar is the largest and most northern, and sun bear is the smallest and near equator
Diverged about 5 million years ago from the lineage leading to polar and brown bears

Malaysian sun bear range

Asiatic Black Bear
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Closely related to American black bear, did not migrate to North
America
Lives in Eastern Asia, inhabiting highlands and tropical forests

Asiatic black bear range

Asiatic Black Bear

American Black Bear
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Most closely related to Asiatic black bear
Lineage containing these two bears split from others in the Ursidae family about 6 million years ago
Within the next million years, these diverged from each other
Migrated to North America about 1-4 million years ago from Europe or Asia
Two found in Meridian during the last year

American Black Bear: Range

American Black Bear

Which bear has this distribution?

Brown or Grizzly bear

Brown Bear
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There are an estimated 125-150,000 brown bears in the wilderness today.
Most are in the former U.S.S.R.
(100,000), in Canada and
Alaska(50,000)
However there are isolated populations in rural France and Spain
(fewer than 100) and even in Mexico

North American range (past and present)

Migration (Brown bears)
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The remote populations remaining in
Europe suggests a migration across Asia to North America, as suggested, during the Pliocene
The lineage containing the ursus bears diverged about 5 million years ago.
The lineage containing the polar bear and the brown bear seems to diverge from each other about 400,000 years ago, making them close relatives (DNA testing)

Polar bear

Polar bear
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Closest relative to brown bear
Most threatened due to depleting ice packs in Artic
Found in Northern Artic
Migration across vast ice expanses very likely

Polar Bear Range

Spectacled bear
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Tramarctos diverged from the last line of the Ursavus line about 10-15 million years ago
Found in Andes Mountains of South
America, its main habitat is the cloud forests of the Andes
It is considered threatened

Spectacled bear Range Map

How?
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Since Gondwanaland and Laurasia were already separated when these bears evolved, the most logical explanation is that the bears speciated from Northern migrant bears, via the Central American land bridge

Spectacled bear