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Evolutionary Journey of the Ursidae Family

Discover the fascinating evolutionary history of Ursidae, from the origins in Paractis to modern bear species, including distribution and migration patterns worldwide.

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Evolutionary Journey of the Ursidae Family

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  1. The Ursidae FamilyAllen Wilson7-29-08Dr. McCall

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

  3. 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

  4. Evolution of Ursidae (cont.) • 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

  5. Cephalogale jaw

  6. More Evolution! • 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

  7. Ursidae family tree

  8. Ursidae Genera • 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

  9. Urisidae phylogeny

  10. Species of Ursidae family • · 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)

  11. Giant Panda • 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

  12. Giant Panda Range

  13. Giant Panda

  14. Sloth Bears • 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

  15. Sloth Bears

  16. Malaysian sun bear • 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

  17. Malaysian sun bear range

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

  19. Asiatic black bear range

  20. Asiatic Black Bear

  21. American Black Bear • 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

  22. American Black Bear: Range

  23. American Black Bear

  24. Which bear has this distribution?

  25. Brown or Grizzly bear

  26. Brown Bear • 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

  27. North American range (past and present)

  28. Migration (Brown bears) • 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)

  29. Polar bear

  30. Polar bear • 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

  31. Polar Bear Range

  32. Spectacled bear • 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

  33. Spectacled bear Range Map

  34. How? • 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

  35. Spectacled bear

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